Cortex - Articles in Press

Scriptwriter's amnesia: Autobiographical memory loss in the documentary film Unknown White Male (2005) - Corrected Proof

Peter A. Kempster, Helene L. Roberts — 2010-03-08

Writers of fictional stories know about both the dramatic and comic effects that can be generated by creating amnesic syndromes for characters. Viewers of cinema and television become well-acquainted with the phenomenon of scriptwriter's amnesia, and do not need special medical or psychological knowledge to understand that it is quite different from the usual types of memory loss that are caused by brain disease. In a recent article titled ‘Memories aren't made of this: amnesia at the movies’, highlighted common elements of these representations of amnesia:

Of rats and men: A reply to Skottun - Corrected Proof

Monica Dhar, Pieter H. Been, Ruud B. Minderaa, Monika Althaus — 2010-03-08

In a letter to Cortex, commented on the use of an animal model that was referred to in our paper () to generate a hypothesis on how the neural development in dyslexia may lead to deficits in visual processing. Here we present a response to this letter.

Object affordance and spatial-compatibility effects in Parkinson's disease - Corrected Proof

Adam Galpin, Steven P. Tipper, Jeremy P.R. Dick, Ellen Poliakoff — 2010-03-02

Abstract: Movement in Parkinson's disease (PD) is strongly influenced by sensory stimuli. Here, we investigated two features of visual stimuli known to affect response times in healthy individuals; the spatial location of an object (the spatial effect) and its action-relevance (the ‘affordance’ effect). found that while PD patients show normal spatial effects, they do not show an additional affordance effect. Here we investigated whether these effects are driven by facilitation or inhibition, and whether the affordance effect emerges over a longer time-course in PD. Participants (24 PD and 24 controls) viewed either a lateralised door handle (affordance condition), a lateralised abstract stimulus (spatial condition), or a centrally presented baseline stimulus (baseline condition), and responded to a colour change in the stimulus occurring after 0msec, 500msec or 1000msec. The colour change indicated whether to respond with the left or right hand, which were either spatially compatible or incompatible with the lateralised stimulus orientation in the affordance and spatial conditions. The baseline condition allowed us to assess whether compatibility effects were driven by facilitation of the compatible response or inhibition of the incompatible response. The results indicate that stimulus orientation elicited faster responses from the nearest hand. For controls, the affordance effect was stronger and driven by facilitation, whilst the spatial condition was driven by inhibition. In contrast, the affordance and spatial-compatibility effects did not differ between conditions in the PD group and both were driven by facilitation. This suggests that the PD group responded as if all stimuli were action-relevant, and may have implications for understanding the cueing of movement in PD.

The multiple meanings of “neuro” in neuropsychology - Corrected Proof

Roberto Cubelli, Sergio Della Sala — 2010-02-25

Cortex was founded in 1964 by Ennio De Renzi. As such it is one of the oldest journals of Neuropsychology, launched at the turning point in the history of the field (see ). According to the blurb presenting it, “Cortex is an international journal devoted to the study of cognition and of the relationship between the nervous system and mental processes, particularly as these are reflected in the behaviour of patients with acquired brain lesions, normal volunteers, children with typical and atypical development, and in the activation of brain regions and systems as recorded by functional neuroimaging techniques”. That is, Neuropsychology, as the composition of the term implies, is typically an interdisciplinary endeavour, which serves as a bridge between different levels of analysis and fills the gap between other disciplines, like the cognitive sciences and the neurosciences (). The nature of such a multidisciplinary, or better yet “super-disciplinary”, approach is well exemplified by in their description of aphasia research: “The interaction of speech pathology, neurology, psychology, computer science and linguistics has led to more elaborate research on remedial programmes and techniques. This converging of different disciplines has also led to an accumulation of data, approaches, techniques and scientific methods which constitute the field of endeavour known as aphasiology.” (p. 3).

Prism adaptation does not change the rightward spatial preference bias found with ambiguous stimuli in unilateral neglect - Corrected Proof

Margarita Sarri, Richard Greenwood, Lalit Kalra, Jon Driver — 2010-02-22

Abstract: Previous research has shown that prism adaptation (prism adaptation) can ameliorate several symptoms of spatial neglect after right-hemisphere damage. But the mechanisms behind this remain unclear. Recently we reported that prisms may increase leftward awareness for neglect in a task using chimeric visual objects, despite apparently not affecting awareness in a task using chimeric emotional faces (). Here we explored potential reasons for this apparent discrepancy in outcome, by testing further whether the lack of a prism effect on the chimeric face task task could be explained by: i) the specific category of stimuli used (faces as opposed to objects); ii) the affective nature of the stimuli; and/or iii) the particular task implemented, with the chimeric face task requiring forced-choice judgements of lateral ‘preference’ between pairs of identical, but left/right mirror-reversed chimeric face tasks (as opposed to identification for the chimeric object task). We replicated our previous pattern of no impact of prisms on the emotional chimeric face task here in a new series of patients, while also similarly finding no beneficial impact on another lateral ‘preference’ measure that used non-face non-emotional stimuli, namely greyscale gradients. By contrast, we found the usual beneficial impact of prism adaptation (prism adaptation) on some conventional measures of neglect, and improvements for at least some patients in a different face task, requiring explicit discrimination of the chimeric or non-chimeric nature of face stimuli. The new findings indicate that prism therapy does not alter spatial biases in neglect as revealed by ‘lateral preference tasks’ that have no right or wrong answer (requiring forced-choice judgements on left/right mirror-reversed stimuli), regardless of whether these employ face or non-face stimuli. But our data also show that prism therapy can beneficially modulate some aspects of visual awareness in spatial neglect not only for objects, but also for face stimuli, in some cases.

Line bisection in unilateral homonymous visual field defects - Corrected Proof

Susanne Schuett, Ruth Dauner, Josef Zihl — 2010-02-22

Abstract: The contralesional line bisection error in unilateral homonymous hemianopia is a frequent but neglected clinical phenomenon. Our knowledge about this bisection error is based on small samples of hemianopic patients. Moreover, horizontal line bisection has never been investigated in other unilateral visual field defects. The present study is the first to examine line bisection in a large, representative sample of patients with unilateral homonymous visual field defects. We investigated horizontal line bisection in 129 patients with left- or right-sided homonymous hemianopia (60.5%), upper and lower quadranopia (24.8%), and paracentral scotoma (14.7%), and determined the magnitude and direction of line bisection error. The contralesional horizontal line bisection error was present not only in patients with hemianopia but also in those with upper or lower quadranopia or paracentral scotoma. Neither the type nor the severity of the visual field defect was found to determine the bisection error. Only the side of the field defect seemed to determine the horizontal direction of the bisection error (left-/rightward). The contralesional bisection error is not a specifically “hemianopic” phenomenon. It is frequently associated with any unilateral homonymous visual field defect, i.e., hemianopia, upper/lower quadranopia, paracentral scotoma. Moreover, our results further support the recent finding that the contralesional bisection error is not a direct consequence of the visual field defect. Yet, they also suggest that, although the visual field defect does not seem to be the primary cause of the contralesional bisection error, it may nevertheless contribute to it.

Cerebellar brain volume accounts for variance in cognitive performance in older adults - Corrected Proof

2010-02-18

Abstract: Introduction: Frontal lobe atrophy is implicated in patterns of age-related cognitive decline. However, other brain areas, including the cerebellum, support the work of the frontal lobes and are also sensitive to the effects of ageing. A relationship between cerebellar brain volume and cognitive function in older adults is reported, but no study has separated variance associated with cerebellar gray matter volume and cerebellar white matter volume; and no study has examined whether or not brain volume in the cerebellum is related to cognitive function in older adults after statistical control for frontal lobe volume of gray and white matter.Method: We used voxel based morphometry (VBM) and structural equation modelling (SEM) to analyse relations between general cognitive ability (G) and volume of GM and WM in frontal areas and cerebellum in a sample of 228 older adults (121 males and 107 females).Results: Results indicate that GM volume in the cerebellum predicts G, even when total intracranial volume (TICV) and GM gray and WM volumes in frontal lobes are statistically controlled. However, results differ for males and females, with males showing a stronger relationship between brain volume in the cerebellum and G.Conclusions: Results are discussed in light of neurological models of cognitive ageing and the significance of the cerebellum in models of cognitive functioning.

Phonological–lexical activation: A lexical component or an output buffer? Evidence from aphasic errors - Corrected Proof

Cristina Romani, Claudia Galluzzi, Andrew Olson — 2010-02-17

Abstract: Single word production requires that phoneme activation is maintained while articulatory conversion is taking place. Word serial recall, connected speech and non-word production (repetition and spelling) are all assumed to involve a phonological output buffer. A crucial question is whether the same memory resources are also involved in single word production. We investigate this question by assessing length and positional effects in the single word repetition and reading of six aphasic patients. We expect a damaged buffer to result in error rates per phoneme which increase with word length and in position effects. Although our patients had trouble with phoneme activation (they made mainly errors of phoneme selection), they did not show the effects expected from a buffer impairment. These results show that phoneme activation cannot be automatically equated with a buffer. We hypothesize that the phonemes of existing words are kept active though permanent links to the word node. Thus, the sustained activation needed for their articulation will come from the lexicon and will have different characteristics from the activation needed for the short-term retention of an unbound set of units. We conclude that there is no need and no evidence for a phonological buffer in single word production.

Cortex covers 2008 - Corrected Proof

Sergio Della Sala, Laura Valkonen — 2010-02-15

As you know, since issue 1, volume 45 (2009), all Cortex covers have been available for downloading from the journal web page (). However, we keep receiving requests to use earlier covers for talks, seminars and lectures. Although we can do nothing for the old covers, we were able to retrieve the original illustrations that were published as cover figures in volume 44, 2008. They are appended to this editorial to allow downloading (see and ).

Impaired capacity for autonoetic reliving during autobiographical event recall in mild Alzheimer's disease - Corrected Proof

Muireann Irish, Brian A. Lawlor, Shane M. O'Mara, Robert F. Coen — 2010-02-15

Abstract: The capacity to mentally travel back in time and relive past events via autonoetic consciousness has been shown to be compromised even in the early stages of Alzheimer's disease (AD). To further understand the unravelling of the recollective experience in pathological ageing, we investigated autobiographical memory (ABM) using the Episodic Autobiographical Memory Interview (EAMI) in thirty middle-aged and thirty healthy elderly controls, and twenty patients with mild AD. Of key interest was the recall of contextual details and the behavioural markers predictive of autonoetic reliving. AD patients exhibited significant difficulties in recalling contextual details across all life epochs on the EAMI manifesting in a negative temporal gradient from the Early Adulthood epoch onwards. Overall there was a low incidence of autonoetic consciousness during ABM recall across all participant groups and life epochs when compared with previous studies. AD patients showed a compromised capacity to mentally relive past memories (AD

Evidence for topographic organization in the cerebellum of motor control versus cognitive and affective processing - Corrected Proof

Catherine J. Stoodley, Jeremy D. Schmahmann — 2010-02-12

Abstract: Patients with cerebellar damage often present with the cerebellar motor syndrome of dysmetria, dysarthria and ataxia, yet cerebellar lesions can also result in the cerebellar cognitive affective syndrome (CCAS), including executive, visual spatial, and linguistic impairments, and affective dysregulation. We have hypothesized that there is topographic organization in the human cerebellum such that the anterior lobe and lobule VIII contain the representation of the sensorimotor cerebellum; lobules VI and VII of the posterior lobe comprise the cognitive cerebellum; and the posterior vermis is the anatomical substrate of the limbic cerebellum. Here we analyze anatomical, functional neuroimaging, and clinical data to test this hypothesis. We find converging lines of evidence supporting regional organization of motor, cognitive, and limbic behaviors in the cerebellum. The cerebellar motor syndrome results when lesions involve the anterior lobe and parts of lobule VI, interrupting cerebellar communication with cerebral and spinal motor systems. Cognitive impairments occur when posterior lobe lesions affect lobules VI and VII (including Crus I, Crus II, and lobule VIIB), disrupting cerebellar modulation of cognitive loops with cerebral association cortices. Neuropsychiatric disorders manifest when vermis lesions deprive cerebro-cerebellar-limbic loops of cerebellar input. We consider this functional topography to be a consequence of the differential arrangement of connections of the cerebellum with the spinal cord, brainstem, and cerebral hemispheres, reflecting cerebellar incorporation into the distributed neural circuits subserving movement, cognition, and emotion. These observations provide testable hypotheses for future investigations.

Cerebral reorganization as a function of linguistic recovery in children: An fMRI study - Corrected Proof

2010-02-08

Abstract: Characterizing and mapping the relationship between neuronal reorganization and functional recovery are essential to the understanding of cerebral plasticity and the dynamic processes which occur following brain damage. The neuronal mechanisms underlying linguistic recovery following left hemisphere (LH) lesions are still unknown. Using functional magnetic resonance imaging (fMRI), we investigated whether the extent of brain lateralization of linguistic functioning in specific regions of interest (ROIs) is correlated with the level of linguistic performance following recovery from acquired childhood aphasia. The study focused on a rare group of children in whom lesions occurred after normal language acquisition, but prior to complete maturation of the brain. During fMRI scanning, rhyming, comprehension and verb generation activation tasks were monitored. The imaging data were evaluated with reference to linguistic performance measured behaviorally during imaging, as well as outside the scanner. Compared with normal controls, we found greater right hemisphere (RH) lateralization in patients. However, correlations with linguistic performance showed that increased proficiency in linguistic tasks was associated with greater lateralization to the LH. These results were replicated in a longitudinal case study of a patient scanned twice, 3 years apart. Additional improvement in linguistic performance of the patient was accompanied by increasing lateralization to the LH in the anterior language region. This, however, was the result of a decreased involvement of the RH. These findings suggest that recovery is a dynamic, ongoing process, which may last for years after onset. The role of each hemisphere in the recovery process may continuously change within the chronic stage.

Rats, dyslexia, and the magnocellular system - Corrected Proof

Bernt Christian Skottun — 2010-02-08

emphasize anomalies of the magnocellular system in connection with dyslexia. Interspersed in their description are references to the cortex of rats. The problem in this connection is that the rat does not have a magnocellular system. The term “magnocellular system” refers specifically to a portion of the subcortical visual system in primates. Thus, as far as magnocellular deficits are concerned, data from primates need to be kept distinctly separate from results from other species.

Please add the journal issue number to Cortex references - Corrected Proof

Sergio Della Sala, Jordan Grafman — 2010-02-08

In writing scientific papers, we quote papers and list references for several reasons. We want to acknowledge previous authors, we want to support our argument with previous literature, and we want to frame our arguments within an existing body of knowledge. References serve the purpose of allowing readers to find the sources that we quote, and read the originals. When we list a journal paper, we typically provide the surname of the author(s) and their initials, the title of the article, the journal, the volume number, and the page numbers of the article. This is true for the most common referencing systems, such as APA, Harvard or Vancouver; and has applied also to Cortex.

The impact of self-citation - Corrected Proof

Jennifer A. Foley, Sergio Della Sala — 2010-02-08

Citation rates are used to calculate journal impact factors and for measuring the personal impact of individual scientists (), which can affect chances of academic appointments, advance in career, pay increases and grant funding ().

Unification of sentence processing via ear and eye: An fMRI study - Corrected Proof

2010-02-01

Abstract: We present new evidence based on fMRI for the existence and neural architecture of an abstract supramodal language system that can integrate linguistic inputs arising from different modalities such that speech and print each activate a common code. Working with sentence material, our aim was to find out where the putative supramodal system is located and how it responds to comprehension challenges. To probe these questions we examined BOLD activity in experienced readers while they performed a semantic categorization task with matched written or spoken sentences that were either well-formed or contained anomalies of syntactic form or pragmatic content. On whole-brain scans, both anomalies increased net activity over non-anomalous baseline sentences, chiefly at left frontal and temporal regions of heteromodal cortex. The anomaly-sensitive sites correspond approximately to those that previous studies () have found to be sensitive to other differences in sentence complexity (object relative minus subject relative). Regions of interest (ROIs) were defined by peak response to anomaly averaging over modality conditions. Each anomaly-sensitive ROI showed the same pattern of response across sentence types in each modality. Voxel-by-voxel exploration over the whole brain based on a cosine similarity measure of common function confirmed the specificity of supramodal zones.

The spectrum of neurobehavioural deficits in the Posterior Fossa Syndrome in children after cerebellar tumour surgery - Corrected Proof

Coriene E. Catsman-Berrevoets, Femke K. Aarsen — 2010-01-29

Abstract: Introduction: The Posterior Fossa Syndrome (PFS) may occur in children after resection of cerebellar tumours. The most common feature is mutism, but also oropharyngeal dyspraxia, emotional lability and neuropsychiatric symptoms occur. We analysed the spectrum of behavioural abnormalities, speech and language characteristics during PFS.Methods: In order to identify PFS, all children with a cerebellar tumour admitted to our centre in the study period were prospectively assessed before and after tumour surgery. In the case of PFS, children were systematically followed by means of a standard protocol that included a daily neurological examination and assessment of speech behaviour. Speech was recorded on videotape before and immediately after surgery, and in cases of PFS at as short possible intervals for 4 weeks and subsequently every second week until the recurrence of speech and normalisation of behaviour. Data regarding clinical and behavioural features, duration of symptoms and mode of recovery were collected. Pre- and postoperative MRI data were studied. In 13 children with and two children without PFS a 99mTc-hexamethylpropyleneamine oxime-Single Photon Emission Tomography (SPECT) scan could be performed.Results: PFS occurred in 41 of 148 children. During recovery all children were dysarthric, but only in a few speech features specific for cerebellar dysarthria occurred. A significant correlation was found between duration of mutism and severity of neurological symptoms. Significant correlations were also found between duration of mutism and abnormalities on SPECT scans of the left temporal lobe, the left and right basal nuclei, and the right frontal lobe.Conclusions: In this study, impairments of higher cognitive functions were observed in the context of PFS. They varied in severity and composition between children with symptoms fitting into the spectrum of the Cerebellar Cognitive Affective Syndrome. SPECT scan findings suggest that these impairments are secondary to supratentorial metabolic hypofunction following cerebellar surgery.

Fractionating the multi-character processing deficit in developmental dyslexia: Evidence from two case studies - Corrected Proof

2010-01-29

Abstract: While there is growing evidence that some dyslexic children suffer from a deficit in simultaneously processing multiple visually displayed elements, the precise nature of the deficit remains largely unclear. The aim of the present study is to investigate possible cognitive impairments at the source of this deficit in dyslexic children. The visual processing of simultaneously presented letters was thus thoroughly assessed in two dyslexic children by means of a task that requires the report of briefly presented multi-letters arrays. A computational model of the attentional involvement in multi-object recognition () served as framework for analysing the data. By combining psychophysical measurements with computational modelling, we demonstrated that the visual processing deficit of simultaneously displayed letters, observed in the two dyslexic individuals reported in the current study, stems from at least two distinct cognitive sources: a reduction of the rate of—letter—information uptake, and a limitation of the maximal number of elements extracted from a brief visual display and stored in visual short-term memory. Possible relations between these impairments and learning to read proficiently are discussed.

Asymmetries in motor attention during a cued bimanual reaching task: Left and right handers compared - Corrected Proof

Gavin Buckingham, Julie C. Main, David P. Carey — 2010-01-25

Abstract: Several studies have indicated that right handers have attention biased toward their right hand during bimanual coordination (). To determine if this behavioral asymmetry was linked to cerebral lateralization, we examined this bias in left and right handers by combining a discontinuous double-step reaching task with a Posner-style hand cueing paradigm. Left and right handed participants received a tactile cue (valid on 80% of trials) prior to a bimanual reach to target pairs. Right handers took longer to inhibit their right hand and made more right hand errors, suggesting that their dominant hand was more readily primed to move than their non-dominant hand, likely due to the aforementioned attentional bias. Left handers, however, showed neither of these asymmetries, suggesting that they lack an equivalent dominant hand attentional bias. The findings are discussed in relation to recent unimanual handedness tasks in right and left handers, and the lateralization of systems for speech, language and motor attention.

When the zebra loses its stripes: Semantic priming in early Alzheimer's disease and semantic dementia - Corrected Proof

2010-01-20

Abstract: Patients suffering from Alzheimer's disease (AD) or semantic dementia (SD) both exhibit deficits on explicit tasks of semantic memory. Semantic priming (SP) paradigms provide a very pure and precise implicit measurement of semantic memory impairment, and a previous study of AD () using one such paradigm revealed that AD patients in the initial stages of semantic deterioration presented an abnormally large priming effect (hyperpriming) in a category-coordinate condition, compared with controls. This astonishing phenomenon could stem from the specific loss of distinctive attributes that make it possible to distinguish between semantically close concepts, while attributes shared by different concepts belonging to a given category remain intact. To test this hypothesis and compare the degradation of semantic memory in AD and SD, we devised an SP paradigm in which word pairs had either a category-coordinate or an attribute relationship. In accordance with our hypothesis, we distinguished between shared (duck–feathers) versus distinctive attributes (zebra–stripes) and close (tiger–lion) versus distant (elephant–crocodile) category-coordinate relationships. This paradigm, together with two explicit semantic memory tasks (picture-naming and categorization), was administered to 16 AD and 8 SD patients and 30 elderly control subjects. The AD patients, at the very beginning of semantic deterioration, only displayed impaired SP effects in the distinctive attribute condition, whereas in the SD patients, who had more severe semantic deterioration, we observed an extinction of SP effects in both attribute conditions. In SD patients, we also report hyperpriming effects in both category-coordinate conditions. Our results suggest that semantic memory impairment follows the same course in both AD and SD, affecting distinctive attributes first and then shared ones. In accordance with distributed models of semantic memory, the loss of distinctive attributes leads to a confusion between close concepts and it is this which causes the transient hyperpriming phenomenon.

Margaret Kennard (1899–1975): Not a ‘Principle’ of brain plasticity but a founding mother of developmentalneuropsychology - Corrected Proof

Maureen Dennis — 2010-01-18

Abstract: According to the ‘Kennard Principle’, there is a negative linear relation between age at brain injury and functional outcome. Other things being equal, the younger the lesioned organism, the better the outcome. But the ‘Kennard Principle’ is neither Kennard's nor a principle. In her work, Kennard sought to explain the factors that predicted functional outcome (age, to be sure, but also staging, laterality, location, and number of brain lesions, and outcome domain) and the neural mechanisms that altered the lesioned brain's functionality. This paper discusses Kennard's life and years at Yale (1931–1943); considers the genesis and scope of her work on early-onset brain lesions, which represents an empirical and theoretical foundation for current developmental neuropsychology; offers an historical explanation of why the ‘Kennard Principle’ emerged in the context of early 1970s work on brain plasticity; shows why uncritical belief in the ‘Kennard Principle’ continues to shape current research and practice; and reviews the continuing importance of her work.

The role of the left anterior temporal lobe in language processing revisited: Evidence from an individual with ATL resection - Corrected Proof

Yanchao Bi, Tao Wei, Chenxing Wu, Zaizhu Han, Tao Jiang, Alfonso Caramazza — 2010-01-14

Abstract: Various hypotheses about the role of the anterior temporal lobe (ATL) in language processing have been proposed. One hypothesis is that it binds the semantic/conceptual properties of words, functioning as a hub for linking modality-specific conceptual properties of objects. This hypothesis predicts that damage to ATL would give rise to impaired conceptual knowledge of all categories. A related school of hypotheses assumes that the left ATL is critical for lexical retrieval, with different sub-regions potentially important for different categories of items. We examined these hypotheses by studying a case of surgical resection of left ATL due to a low-grade glioma (LGG). Thorough language assessments performed four months after the operation revealed the following profile: the patient showed intact conceptual knowledge for all categories of items tested using both accuracy and response latency measures; he suffered from name retrieval deficits for proper names (people and place names) and artifacts (including tools), but showed no name retrieval difficulties for animate things. This pattern of results challenges both target hypotheses about the role of ATL in language processing tested here.

Patterns of breakdown in spelling in primary progressive aphasia - Corrected Proof

2010-01-11

Abstract: Introduction: The objective of this study is to determine which cognitive processes underlying spelling are most affected in the three variants of primary progressive aphasia (PPA): Logopenic variant primary progressive aphasia (lvPPA), Semantic variant primary progressive aphasia (svPPA), and Nonfluent variant primary progressive aphasia (nfvPPA).Methods: 23 PPA patients were administered The Johns Hopkins Dysgraphia Battery to assess spelling. Subtests evaluate for effects of word frequency, concreteness, word length, grammatical word class, lexicality (words vs pseudowords), and “regularity” by controlling for the other variables. Significant effects of each variable were identified with chi square tests. Responses on all spelling to dictation tests were scored by error type. 16 of the 23 subjects also had a high resolution MRI brain scan to identify areas of atrophy.Results: We identified 4 patterns of spelling that could be explained by damage to one or more cognitive processes underlying spelling. Nine patients (3 unclassifiable, 4 with lvPPA, 2 with svPPA) had dysgraphia explicable by impaired access to lexical representations, with reliance on sublexical phonology-to-orthography conversion (POC). Two patients (with nfvPPA) showed dysgraphia explicable by impaired access to lexical representations and complete disruption of sublexical POC. Seven patients (4 with lvPPA, 1 with svPPA, 2 unclassifiable) showed dysgraphia explicable by impaired access to lexical-semantic representations and/or lexical representations with partially spared sublexical POC mechanisms. Five patients (1 with nfvPPA, 2 with svPPA, 1 with lvPPA, and 1 unclassifiable) showed dysgraphia explicable by impairment of the graphemic buffer.Conclusions: Any cognitive process underlying spelling can be affected in PPA. Predominance of phonologically plausible errors, more accurate spelling of regular words than irregular words, and more accurate spelling of pseudowords than words (indicating spared POC mechanisms) may indicate a low probability of progression to nfvPPA.

Impaired acquisition of a mirror-reading skill in Alzheimer's disease - Corrected Proof

Sarah Merbah, Eric Salmon, Thierry Meulemans — 2010-01-11

Abstract: Several studies using the mirror-reading paradigm have shown that procedural learning and repetition priming may be preserved in the early stages of Alzheimer's disease (AD) (e.g., ). According to the classical interpretation, improved reading time for repeated words is sustained by a repetition priming effect, while procedural learning is demonstrated when this improvement is also observed for new words. Following , the hypothesis tested in the present study was that improved reading of new words could also be due to a repetition priming effect rather than to the acquisition of a mirror-reading skill. Indeed, because the same letters are presented throughout the task, a repetition priming effect for the letters could suffice to explain the improvement in performance. To test this hypothesis, we administered to 30 healthy young and elderly subjects and to 30 AD patients a new mirror-reading task in two phases: an acquisition phase comprising pseudo-words constructed with one part of the alphabet, and a test phase in which both pseudo-words constructed with the same part of the alphabet and pseudo-words constructed with another part of the alphabet were presented. If the new pseudo-words composed with repeated letters were read faster, it would reflect a repetition priming effect; if pseudo-words composed of ‘new’ letters were read faster, it would reflect a procedural learning effect. The results show comparable repetition priming effects in AD patients and in healthy elderly subjects, whereas only healthy subjects showed a procedural learning effect. These results suggest, contrary to previous studies, that the learning of a new perceptual skill may not always be preserved in AD.

Neural response to the behaviorally relevant absence of anticipated outcomes and the presentation of potentially harmful stimuli: A human fMRI study - Corrected Proof

Louis Nahum, Stéphane R. Simon, David Sander, François Lazeyras, Armin Schnider — 2010-01-11

Abstract: Adaptive behavior requires the ability to react to potentially harmful stimuli, characterized by high negative inherent emotional salience (iES) (e.g., spiders, snakes), and to the unexpected non-occurrence of anticipated events. When presented simultaneously, threatening stimuli and unexpected absence of anticipated outcomes induce distinct electrocortical responses in different time periods. In this study, we used fMRI to test whether processing of the absence of anticipated outcomes (prediction errors) was anatomically dissociated from the processing of iES or whether iES simply modulated activity of areas processing the non-occurrence of anticipated outcomes. Participants saw two alternating pairs of faces and indicated for each pair which one would have a declared target stimulus on its nose. Depending on the condition, the target stimulus was either a spider (high iES stimulus) or a disk (low iES stimulus). The target stimulus switched to the other face after several consecutive correct responses, with the switch being indicated by the appearance of the alternative stimulus (disk when the spider was the declared target; spider when the disk was the declared target). We found that the spider induced stronger activation in visual areas than the disk. By contrast, the absence of anticipated outcomes specifically activated the orbitofrontal cortex (OFC), irrespective of the iES of the outcome stimulus. The findings support a generic role of the OFC in outcome monitoring.

The cerebellum and dyslexia - Corrected Proof

Catherine J. Stoodley, John F. Stein — 2010-01-08

Abstract: It has been proposed that cerebellar dysfunction is an underlying cause of developmental dyslexia, which is diagnosed when there is an unexpected discrepancy between a child's reading ability and his or her cognitive skills. Traditionally, the cerebellum is thought to be involved in motor control, although in the last 15 years mounting evidence suggests a cerebellar role in higher-level cognitive processes. Clinical, neuroimaging, and behavioral studies have all supported a role for the cerebellum in dyslexia. Clinical studies document acquired language and reading difficulties in patients with cerebellar damage or degeneration. Both structural and functional imaging studies suggest that the cerebella of dyslexic individuals differ both morphologically and functionally from good readers. In particular, the posterolateral right cerebellar hemisphere (that connects with the left cerebral cortex) is both smaller in size and shows differential activation patterns in some dyslexic individuals. Behavioral studies of “cerebellar” tasks have assessed balance and motor skills, eye-movement control, classical conditioning, and implicit learning in dyslexic participants. Results indicate that at least a subset of dyslexic children and adults performed poorly on these tasks. In some cases, dyslexics' performance correlated with literacy skills and/or the degree of discrepancy between cognitive and literacy skills. However, despite these findings, it remains unlikely that cerebellar dysfunction is the main cause of dyslexia. There are many negative results, only a few clinical reports of acquired dyslexia resulting from cerebellar damage, and questionable specificity of cerebellar involvement in dyslexia, as several other neurodevelopmental disorders show associated cerebellar abnormalities. That said, it is likely that the cerebellum is part of the distributed neural circuitry that is impaired in developmental dyslexia. Future studies should aim to understand this role better in the context of cerebellar regional anatomy and the connections between the cerebellum and the cortical and sub-cortical regions involved in reading.

Extensive video-game experience alters cortical networks for complex visuomotor transformations - Corrected Proof

Joshua A. Granek, Diana J. Gorbet, Lauren E. Sergio — 2010-01-08

Abstract: Using event-related functional magnetic resonance imaging (fMRI), we examined the effect of video-game experience on the neural control of increasingly complex visuomotor tasks. Previously, skilled individuals have demonstrated the use of a more efficient movement control brain network, including the prefrontal, premotor, primary sensorimotor and parietal cortices. Our results extend and generalize this finding by documenting additional prefrontal cortex activity in experienced video gamers planning for complex eye-hand coordination tasks that are distinct from actual video-game play. These changes in activation between non-gamers and extensive gamers are putatively related to the increased online control and spatial attention required for complex visually guided reaching. These data suggest that the basic cortical network for processing complex visually guided reaching is altered by extensive video-game play.

The cerebellum and its contribution to complex tasks in higher primates: A comparative perspective - Corrected Proof

Claudio Cantalupo, William Hopkins — 2009-11-19

Abstract: Many aspects of the involvement of the cerebellum in motor control and cognition are still quite unclear or relatively unexplored. In particular, very little is known about the evolution of cerebellar contribution to complex behavior in higher primate species. In this paper, we provide an overview of existing and ongoing comparative studies of the role of the cerebellum in primate behavior. In particular, we discuss evidence that great apes show greater cerebellar relative size than monkeys and that such interspecific difference is mainly explained by growth of the lateral neocerebellum in evolution with converse changes in the vermis. Furthermore, we present evidence that volumetric differences as well as lateral asymmetry of the cerebellum are related to both performance and hand preference for skilled tasks like tool use and aimed throwing. Finally we suggest future directions for this comparative research area that may offer further valuable clues into the involvement of the cerebellum in complex behavior and its evolutionary origin in primate species.

Phantom limb after stroke: An underreported phenomenon - Corrected Proof

Daniel Antoniello, Benzi M. Kluger, Daniel H. Sahlein, Kenneth M. Heilman — 2009-11-16

Abstract: The presence of a phantom limb (PL) resulting from a cerebral lesion has been reported to be a rare event. No prior study, however, has systematically investigated the prevalence of this syndrome in a group of post-stroke individuals. Fifty post-stroke individuals were examined with structured interview/questionnaire to establish the presence and perceptual characteristics of PLs. We document the presence of phantom experiences in over half of these individuals (n=27). We provide details of these phantom experiences and further characterize these symptoms in terms of temporal qualities, posture, kinesthesia, and associated features. Twenty-two participants reported postural phantoms, which were perceived as illusions of limb position that commonly manifested while lying in bed at night – a time when visual input is removed from multi-sensory integration. Fourteen participants reported kinesthetic phantoms, with illusory movements ranging from simple single joint sensations to complex goal-directed phantom movements. A striking syndrome of near total volitional control of phantom movements was reported in four participants who had immobile plegic hands. Reduplicative phantom percepts were reported by only one participant. Similarly, phantom pain was present in only one individual – the sole participant with a pre-stroke limb amputation. The results suggest that stroke results in phantom experiences more commonly than previously described in the literature. We speculate that subtotal deafferance or defective motor efference after stroke may manifest intermittently as a PL.

Two qualitatively different impairments in making rotation operations - Corrected Proof

Tania Buiatti, Alessandro Mussoni, Alessio Toraldo, Miran Skrap, Tim Shallice — 2009-11-16

Abstract: It is widely recognized that mental rotation is a cognitive process which engages a distributed cortical network including the frontal, premotor and parietal regions. Like other visual-spatial transformations it could require operations on both metric and categorical spatial representations. Previous reports have implicated respectively the right hemisphere being involved in the metric processing and the left hemisphere in the categorical processing. By using a modified version of the , we attempted to establish the cortical regions relevant for the categorical and metric aspects of mental rotation transformations. Two groups of patients were found to be impaired in our study, namely the left prefrontal and the right parietal. In particular, whereas the right parietal group made poor use of categorical information, the left prefrontal patients showed a broader mental rotation impairment with a significant number of metric errors. The results are discussed in terms of the model of about the possible mental transformation impairments following brain lesions.

Specific impairments in visual processing following lesion side in hemianopic patients - Corrected Proof

2009-11-02

Abstract: Introduction: Following unilateral damage of the primary visual cortex one of the most common visual field defects observed is Homonymous Hemianopia (HH), a loss of vision of the contralesional hemifield in each eye. The ipsilesional (“intact”) part of the central visual field is often used to compensate for difficulties encountered in the peripheral hemianopic visual field. However, the quality of vision within the central visual field is not well-known.Methods: To better describe and understand visual processing in hemianopia, two tasks were conducted with 25 healthy controls, six left hemianopes, and five right hemianopes. Filtered (in high, above 6 cycles/degree, or low, below 4 cycles/degree, spatial frequencies – HSF and LSF, respectively) and unfiltered natural scene images (5° of visual angle) were briefly presented (100msec) centrally on a computer screen. Participants were required either to respond when a natural scene was presented (yes/no detection task) or to indicate if the stimulus was a city or a highway (categorization task).Results: The three groups showed similar accuracy levels but significant differences were observed in response times. More precisely, left hemianopes were impaired both in the detection and in the categorization tasks whereas right hemianopes were only impaired in the categorization task. However, the three groups had similar responses to spatial frequencies: HSF were processed more slowly than LSF.Conclusions: Overall these results suggest that central vision is not intact in hemianopia. Lesion side selectively affects reaction times (RTs) in the detection and the categorization tasks, but does not seem to determine a specific deficit in spatial frequency processing.

Acknowledgements - Corrected Proof

2009-11-02

The editors of Cortex are extremely grateful to the following ad hoc reviewers who helped review manuscripts submitted in the year 2009:

Is the visual analyzer orthographic-specific? Reading words and numbers in letter position dyslexia - Corrected Proof

Naama Friedmann, Dror Dotan, Einav Rahamim — 2009-10-26

Abstract: Letter position dyslexia (LPD) is a deficit in the encoding of letter position within words. It is characterized by errors of letter migration within words, such as reading trail as trial and form as from. In order to examine whether LPD is domain-specific, and to assess the domain-specificity of the visual analysis system, this study explored whether LPD extends to number reading, by testing whether individuals who have letter migrations in word reading also show migrations while reading numbers. The reading of words and numbers of 12 Hebrew-speaking individuals with developmental LPD was assessed. Experiment 1 tested reading aloud of words and numbers, and Experiment 2 tested same–different decisions in words and numbers. The findings indicated that whereas the participants with developmental LPD showed a large number of migration errors in reading words, 10 of them read numbers well, without migration errors, and not differently from the control participants. A closer inspection of the pattern of errors in words and numbers of two individuals who had migrations in both numbers and words showed qualitative differences in the characteristics of migration errors in the two types of stimuli. In word reading, migration errors appeared predominantly in middle letters, whereas the errors in numbers occurred mainly in final (rightmost) digits. Migrations in numbers occurred almost exclusively in adjacent digits, but in words migrations occurred both in adjacent and in nonadjacent letters. The results thus indicate that words can be selectively impaired, without a parallel impairment in numbers, and that even when numbers are also impaired they show different error pattern. Thus, the visual analyzer is actually an orthographic visual analyzer, a module that is domain-specific for the analysis of words.

Evidence for a link among cognition, language and emotion in cerebellar malformations - Corrected Proof

Alessandro Tavano, Renato Borgatti — 2009-10-26

Abstract: We compared the neurobehavioral profiles of children with Joubert syndrome (JS participants), a rare autosomal recessive condition characterized on magnetic resonance imaging (MRI) by hypoplasia of the cerebellar vermis and midbrain–hindbrain malformations, and children with malformations confined to the cerebellar vermis and one or both hemispheres (Cerebellar malformations – CM participants). We aimed at investigating the influence of anatomo-clinical similarities (vermian malformation) and differences (intact cerebellar hemispheres vs sparing of the pons, respectively) with respect to cognitive, linguistic and emotional development, assuming as a reference framework the Cerebellar Cognitive Affective Syndrome (CCAS). Results show that severe to moderate mental retardation is infrequent in JS children, while it is present in more than half the sample of CM children. Affect development was generally preserved in JS, in high-functioning CM individuals and also in some of the CM children with moderate mental retardation, which raised questions as to the role of a cerebellar vermis lesion in determining affect disorders. Further, cognitive and linguistic profiles on both intellectual and neuropsychological evaluations provided evidence for distinct patterns of peaks and valleys in the two groups, with JS children being significantly more impaired in language and verbal working memory and CM individuals showing a significant impairment of executive functions and emotional development. The overall evidence provides support for an important role of cerebellar structures per se in shaping emotional, cognitive and linguistic development, when vermian lesions are associated to cerebellar hemispheric lesions. Cerebellar vermis and brainstem lesions instead appear to have a major impact on motor-related skills, including oro-motor abilities and verbal working memory.

Cognitive and affective disturbances following focal cerebellar damage in adults: A neuropsychological and SPECT study - Corrected Proof

2009-10-26

Abstract: The traditional view on cerebellar functioning has recently been challenged by results from neuroanatomical, neuroimaging and clinical studies. In this contribution, eighteen patients with primary cerebellar lesions (vascular: n=13; neoplastic: n=5) were systematically investigated by means of an extensive neuropsychological test battery. Fifteen patients (83%) presented with a broad variety of cognitive and linguistic deficits following cerebellar damage. Disturbances of attention (72%), executive functioning (50%) and memory (50%) were most commonly found. Analyses of our results tend to support the hypothesis of a lateralization of cognitive modulation within the cerebellum, the right cerebellar hemisphere being associated with logical reasoning and language processing and the left cerebellum mediating right-hemispheric functions including attentional and visuo-spatial skills. In addition, nine patients (50%) presented with frontal-like behavioural and affective alterations. In an attempt to determine the working-mechanism underlying cerebellar-induced cognitive and affective disturbances, all patients were investigated by means of quantified Tc-99m-ethylenecysteine dimer (ECD) single photon emission computerized tomography (SPECT) studies. From a semiological point of view, damage to the cerebellum can cause a broad spectrum of clinically significant cognitive and affective disturbances. From a pathophysiological point of view, quantified SPECT data, reflecting the phenomenon of cerebello-cerebral diaschisis, support the functional impact of the cerebellar lesion on cortical functioning through disruption of cerebello-cerebral connections.

Functional activation in the cerebellum during working memory and simple speech tasks - Corrected Proof

Corrine Durisko, Julie A. Fiez — 2009-10-23

Abstract: Verbal working memory is the ability to temporarily store and manipulate verbal information. This study tested the predictions of a neuroanatomical model of how the cerebellum contributes to verbal working memory (). In this model, a large bilateral region in the superior cerebellum is associated with articulatory rehearsal and a right-lateralized region in the inferior cerebellum is associated with the correction of errors within the working memory system. The model was based on neuroimaging findings using item recognition tasks and comparisons between working memory and covert rehearsal tasks, whereas in this functional magnetic resonance imaging (fMRI) study we used a delayed serial recall (DSR) task because it relies more heavily on articulatory rehearsal, and our comparison tasks included both overt and covert speech tasks. Our results provide some support for the model. In particular, we found multiple activation foci within the superior and inferior sectors of the cerebellum and evidence that these regions show different patterns of activation across working memory and speech tasks. However, the specific patterns of activation were not fully consistent with those reported by . Namely, our results indicate that activation in the superior sector should be functionally subdivided into a medial focus involved in speech processing and a lateral focus more specific to verbal working memory; the results also indicate that activation in the inferior sector is not uniquely right lateralized. These complex findings speak to the need for future studies to consider the speech-motor aspects of tasks, to investigate the functional significance of adjacent peaks of activation within large regions of cerebellar activation, and to use analysis procedures that support regional distinctions through direct statistical tests. Such studies would help to refine our understanding of how the cerebellum contributes to speech and verbal working memory.

Covert processing of facial expressions by people with Williams syndrome - Corrected Proof

Yonata Levy, Hadas Pluber, Shlomo Bentin — 2009-10-23

Abstract: Although individuals with Williams Syndrome (WS) are empathic and sociable and perform relatively well on face recognition tasks, they perform poorly on tasks of facial expression recognition. The current study sought to investigate this seeming inconsistency. Participants were tested on a Garner-type matching paradigm in which identities and expressions were manipulated simultaneously as the relevant or irrelevant dimensions. Performance of people with WS on the expression-matching task was poor and relied primarily on facilitation afforded by congruent identities. Performance on the identity matching task came close to the level of performance of matched controls and was significantly facilitated by congruent expressions. We discuss potential accounts for the discrepant processing of expressions in the task-relevant (overt) and task-irrelevant (covert) conditions, expanding on the inherently semantic-conceptual nature of overt expression matching and its dependence on general cognitive level.

Exogenous phasic alerting and spatial orienting in mild cognitive impairment compared to healthy ageing: Study outcome is related to target response - Corrected Proof

2009-10-21

Abstract: Whether or not attentional mechanisms such as phasic alerting, spatial cueing and inhibition of return (IOR) remain intact in adults with Alzheimer's disease (AD) and mild cognitive impairment (MCI) remains a matter of debate. This is possibly the result of inter-study outcome variation caused by the adoption of different methodological components by different research groups. Here we investigated the influence of methodological factors upon study outcome, using a Posner-type exogenous cueing paradigm with amnestic MCI patients and healthy older controls. Specifically, we compared results when the required response involved target discrimination with results for a simple target detection response, using cue-to-target intervals (CTIs) of 200msec and 800msec in each case and with the same participants completing all conditions.For both groups, the presence or absence of both alerting and spatial cue-related effects depended upon the combination of target response requirement and CTI. Moreover, differences between the groups were specific to certain task conditions. The MCI group showed the same alerting effects as healthy people with a discrimination response, but the alerting effect shown by controls with a 200msec CTI and target detection was absent in MCI. Patients and controls showed similar spatial cue validity effects at 200msec CTI, but group differences emerged at 800msec CTI: target discrimination evoked a validity effect in the MCI group only, while target detection evoked an IOR effect in the healthy group only. These data indicate that detection and discrimination responses may each activate different attentional mechanisms, which are themselves differentially vulnerable in MCI. Thus a seemingly arbitrary choice of response may directly influence whether attentional processing appears preserved or disrupted in MCI. Furthermore, these data provide further evidence in support of the existence of significant visual attention-related functional abnormalities in amnestic MCI.

Letter position dysgraphia - Corrected Proof

Aviah Gvion, Naama Friedmann — 2009-10-21

Abstract: The article describes AE, a Hebrew-speaking individual with acquired dysgraphia, who makes mainly letter position errors in writing. His dysgraphia resulted from impairment in the graphemic buffer, but unlike previously studied patients, most of his errors related to the position of letters rather than to letter identity: 80% of his errors were letter position errors in writing, and only 7% of his errors were letter omissions, substitutions, and additions. Letter position errors were the main error type across tasks (writing to dictation and written naming), across output modalities (writing and typing), and across stimuli, e.g., migratable words (words in which letter migration forms another word), irregular words, and nonwords. Letter position errors occurred mainly in the middle letters of a word. AE's writing showed a significant length effect, and no lexicality, migratability, or frequency effects. His letter position deficit was manifested selectively in writing; he made no letter position errors in reading, demonstrating the dissociability of letter position encoding in reading and writing. These data support the existence of a letter order function in the graphemic buffer that is separate from the function responsible for activating letter identities.

Functional localization in the cerebellum - Corrected Proof

Mitchell Glickstein, Fahad Sultan, Jan Voogd — 2009-10-16

Abstract: In this paper we review the basic anatomy and functional localization in the cerebellum. Experimental anatomical studies emphasize the predominance of skeletomotor and visuomotor connections. Parietal lobe visual inputs arise principally from the dorsal stream extrastriate visual areas, which are specialized for the visual control of movement. There are few or no inputs to the cerebellum from inferotemporal cortex. Much of the input from prefrontal cortex is from areas that control eye movements. Comparative anatomical studies of the hominoid dentate nucleus are consistent with the role of much of the cerebellar hemispheres in the visual guidance of movement. Although some mossy and climbing fibre afferents to the cerebellum are reciprocally organized, feeding back onto their original source, the reciprocity does not exist for the visuomotor division. The dorsal paraflocculus receives its mossy fibres from extrastriate areas of the dorsal visual stream, and projects to the frontal eye fields. Functional magnetic resonance imaging (fMRI) studies in human subjects confirm the presence of somatotopically organized anterior and posterior skeletomotor areas with eye movement activity centred in the oculomotor vermis. Oculomotor and skeletomotor representation extend into adjacent Crus I and II. Discrepancies between the results of imaging studies in human subjects and experimental data are discussed. Skeletomotor activity or eye movements may contaminate many fMRI studies of putative cognitive functions of the cerebellum.

Exploring theory of mind after severe traumatic brain injury - Corrected Proof

2009-10-15

Abstract: Previous studies have reported a dissociation between social behavioral impairments after severe traumatic brain injury (TBI) and relatively preserved performances in traditional tasks that investigate cognitive abilities. Theory of mind (ToM) refers to the ability to make inferences about other's mental states and use them to understand and predict others' behavior. We tested a group of 15 patients with severe TBI and 15 matched controls on a series of four verbal and non-verbal ToM tasks: the faux pas test, the first-order and second-order false belief task, the character intention task and the Reading the Mind in the Eyes Test. Participants with severe TBI were also compared to controls on non-ToM inference tasks of indirect speech act from the Montreal Evaluation of Communication (M.E.C.) Protocol and empathy (Davis Interpersonal Reactivity Index – I.R.I.) and tests for executive functions. Subjects with TBI performed worse than control subjects on all ToM tasks, except the first-order false belief task. The findings converge with previous evidence for ToM deficit in TBI and dissociation between ToM and executive functions. We show that ToM deficit is probably distinct from other aspects of social cognition like empathy and pragmatic communication skills.

Spatial coding and invariance in object-selective cortex - Corrected Proof

Thomas Carlson, Hinze Hogendoorn, Hubert Fonteijn, Frans A.J. Verstraten — 2009-10-15

Abstract: The present study examined the coding of spatial position in object selective cortex. Using functional magnetic resonance imaging (fMRI) and pattern classification analysis, we find that three areas in object selective cortex, the lateral occipital cortex area (LO), the fusiform face area (FFA), and the parahippocampal place area (PPA), robustly code the spatial position of objects. The analysis further revealed several anisotropies (e.g., horizontal/vertical asymmetry) in the representation of visual space in these areas. Finally, we show that the representation of information in these areas permits object category information to be extracted across varying locations in the visual field; a finding that suggests a potential neural solution to accomplishing translation invariance.

The cerebellum and language: Historical perspective and review - Corrected Proof

Bruce E. Murdoch — 2009-10-15

Abstract: Investigation of a possible role for the cerebellum in the mediation of cognitive processes, including language, has historically been overshadowed by research interest in cerebellar coordination of motor control. Over the past two decades, however, the question of a possible participation of the cerebellum in language processing itself has come to the forefront. In particular recent advances in our understanding of the neuroanatomy of the cerebellum combined with evidence from functional neuroimaging, neurophysiological and neuropsychological research, have extended our view of the cerebellum from that of a simple coordinator of autonomic and somatic motor function. Rather it is now more widely accepted that the cerebellum, and in particular the right cerebellar hemisphere, participates in modulation of cognitive functioning, especially to those parts of the brain to which it is reciprocally connected. The present paper reviews the neuroanatomical, clinical and functional neuroimaging evidence suggestive of a role for the cerebellum in language processing. The possible neuropathophysiological substrates of language impairment associated with cerebellar pathology are discussed and the nature of the linguistic deficits associated with disease or damage to the cerebellum described.

Mechanisms of cerebellar involvement in associative learning - Corrected Proof

Christian Bellebaum, Irene Daum — 2009-10-12

Abstract: Recent theories on cerebellar contributions to cognition emphasize common processing principles in both motor and non-motor domains. In motor control, the cerebellum codes the prediction of the sensory consequences of movements. Correct predictions are dependent upon an internal model in the cerebellum, which develops as a result of past experience and which is updated whenever there is a mismatch between prediction and sensory feedback. Similarly, predictions play a central role in motor and non-motor associative learning tasks on which patients with cerebellar dysfunction show impairments. The present review outlines the evidence for the hypothesis that the cerebellum makes a critical contribution to the prediction of the feedback or outcome associated with sensory input or actions, and that associative learning deficits after cerebellar damage might be linked to an inability to update the internal model based on error feedback. Although considerable empirical support has recently become available, this view needs to be corroborated by further research.

The neural correlate of colour distances revealed with competing synaesthetic and real colours - Corrected Proof

Bruno Laeng, Kenneth Hugdahl, Karsten Specht — 2009-10-12

Abstract: Synaesthetes claim to perceive illusory colours when reading alphanumeric symbols so that two colours are said to be bound to the same letter or digit (i.e., the colour of the ink, e.g., black, and an additional, synaesthetic, colour). To explore the neural correlates of this phenomenon, we used a Stroop single-letter colour-naming task and found that distances in colour space between the illusory and real colours of a letter target (as computed from either the RGB or CIExyY coordinates of colours) systematically influenced the degree of neuronal activation in colour-processing brain regions. The synaesthetes also activated the same fronto-parietal network during the classic colour-word Stroop task and single-letter tasks. We conclude that the same neural substrate that supports the conscious experience of colour, as triggered by physical wavelength, supports the experience of synaesthetic colours. Thus, two colour attributes (one that is wavelength-dependent and one that is illusory) can be bound to the same stimulus position and simultaneously engage the colour areas in proportion to their similarity in colour space.

Reduced interhemispheric coherence in dyslexic adults - Corrected Proof

Monica Dhar, Pieter H. Been, Ruud B. Minderaa, Monika Althaus — 2009-10-12

Abstract: Introduction: Developmental dyslexia has been associated with reduced interhemispheric neural connectivity in children. The present study investigated functional interhemispheric connectivity in male dyslexic adults.Methods: A group of 19 dyslexic men were compared to a group of 15 controls on interhemispheric coherence of the dominant frequency in the power spectrum during a visuo-spatial attention task. The coherence between a left hemisphere central–parietal electrode and the respective right hemisphere electrode and surrounding sites was analysed.Results: Compared to controls, the dyslexic group demonstrated reduced, and more diffuse, interhemispheric coherence of alpha activity in the central–parietal cortex. No group differences in interhemispheric coherence were found on frontal, temporal or central sites.Conclusions: The deviant pattern of functional connectivity in dyslexics is suggestive of an altered development of neural circuitry that may lead to deficits in magnocellular processing.

Dyslexia, dysgraphia, procedural learning and the cerebellum - Corrected Proof

Roderick I. Nicolson, Angela J. Fawcett — 2009-10-09

Abstract: There is confusion over classification in the developmental disorders. Not only is there marked heterogeneity within any given disorder but there is also substantial overlap (‘comorbidity’) between the characteristic symptoms of several disorders. Confusion is particularly marked for dyslexia (defined in terms of poor reading) and dysgraphia (defined in terms of poor writing). Many of these overlapping symptoms may be attributable to abnormal function of neural systems involving the cerebellum. In this paper we apply the ‘neural systems’ framework to the distinction between dyslexia and dysgraphia, developing the thesis that both disorders derive from impairment in components of the procedural learning system. We claim that dyslexia is associated primarily with the language-based component (including Broca's area and the right lateral cerebellum) whereas dysgraphia is associated primarily with the motor component (including the cerebellum and motor cortex). A key step forward in this analysis is the acknowledgment that differences between the different components are in terms of degree rather than all-or-none. For many individuals with dyslexia or dysgraphia these impairments co-occur. Comorbidity between disorders is handled naturally within the framework, and provides a link not only to diagnosis but also to support. The framework has applicability for the understanding of several developmental disorders and will prove fruitful in proposing the development of assessment tools based on neural systems performance rather than attainment measures such as literacy.

How time modulates spatial responses - Corrected Proof

Antonino Vallesi, Anthony R. McIntosh, Donald T. Stuss — 2009-10-09

Abstract: Behavioural evidence suggests a left-to-right directionality in the representation of elapsing time. We tested whether this representation produces a spatial attentional shift that activates a corresponding left-to-right spatial response code. Fourteen participants judged whether a cross lasted for a short (1sec) or a long (2sec) duration with left and right responses, respectively, or vice versa, while event-related potentials (ERPs) were measured. Responses were faster when participants judged short and long durations with their left and right hand, respectively, than vice versa. In these compatible conditions only (short-left; long-right), ERP negativity developed over the right motor scalp region around the short duration, a finding that is compatible with an early pre-activation of left-hand responses, and over the left motor region around the long duration, suggesting a later pre-activation of right hand responses. These findings confirm that in this task elapsing time is represented from left to right, and that this representation generates corresponding response codes that influence performance.

The contributions of cerebro-cerebellar circuitry to executive verbal working memory - Corrected Proof

Cherie L. Marvel, John E. Desmond — 2009-10-07

Abstract: Contributions of cerebro-cerebellar function to executive verbal working memory were examined using event-related functional magnetic resonance imaging (fMRI) while 16 subjects completed two versions of the Sternberg task. In both versions subjects were presented with two or six target letters during the encoding phase, which were held in memory during the maintenance phase. A single probe letter was presented during the retrieval phase. In the “match condition”, subjects decided whether the probe matched the target letters. In the “executive condition”, subjects created a new probe by counting two alphabetical letters forward (e.g., f→h) and decided whether the new probe matched the target letters. Neural activity during the match and executive conditions was compared during each phase of the task. There were four main findings. First, cerebro-cerebellar activity increased as a function of executive load. Second, the dorsal cerebellar dentate co-activated with the supplementary motor area (SMA) during encoding. This likely represented the formation of an articulatory (motor) trajectory. Third, the ventral cerebellar dentate co-activated with anterior prefrontal regions Brodmann Area (BA) 9/46 and the pre-SMA during retrieval. This likely represented the manipulation of information and formation of a response. A functional dissociation between the dorsal “motor” dentate and “cognitive” ventral dentate agrees with neuroanatomical tract tracing studies that have demonstrated separate neural pathways involving each region of the dentate: the dorsal dentate projects to frontal motor areas (including the SMA), and the ventral dentate projects to frontal cognitive areas (including BA 9/46 and the pre-SMA). Finally, activity during the maintenance phase in BA 9, anterior insula, pre-SMA and ventral dentate predicted subsequent accuracy of response to the probe during the retrieval phase. This finding underscored the significant contribution of the pre-SMA/ventral dentate pathway – observed several seconds prior to any motor response to the probe – to executive verbal working memory.

Karl Kleist (1879–1960) – the man behind the map - Corrected Proof

Claus-Werner Wallesch — 2009-10-05

The localizing map of the left hemisphere's cortex; taken from Karl Kleist's monumental book “Gehirnpathologie” (1934), is one of the most often reproduced figures in neuropsychological textbooks (cover, Figs. 1 and 2). He wrote this book as professor of Neurology and Psychiatry at Frankfurt University. Until the 1950s, Kleist was the leading German localizationist. By a strange twist of fate, during the late 1920s, Kurt Goldstein, the leading anti-localizationist, held a second chair of neurology at the same university. Goldstein's major work, “The Organism”, appeared almost simultaneously with Kleist's work in 1934, although already from exile in Amsterdam.