Cortex RSS feed: Current Issue. 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. It was founded in 1964 by Ennio De Renzi.http://www.cortexjournal.net/?rss=yesElsevier Inc.en © 2009 Published by Elsevier Inc. All rights reserved. Cortex0010-9452464April 2010 © 2009 Published by Elsevier Inc. All rights reserved. healthpermissions@elsevier.comhttp://www.cortexjournal.net/article/PIIS0010945210000699/abstract?rss=yesCover Figure10.1016/S0010-9452(10)00069-9Cortex 46, 4 (2010)2010-04-01Cortex2010-04-01464S0010-9452(10)X0003-Xe1e1http://www.cortexjournal.net/article/PIIS0010945210000705/abstract?rss=yesEditorial Board/Title Page10.1016/S0010-9452(10)00070-5Cortex 46, 4 (2010)2010-04-01Cortex2010-04-01464S0010-9452(10)X0003-Xiihttp://www.cortexjournal.net/article/PIIS0010945210000729/abstract?rss=yesContents10.1016/S0010-9452(10)00072-9Cortex 46, 4 (2010)2010-04-01Cortex2010-04-01464S0010-9452(10)X0003-Xiiiivhttp://www.cortexjournal.net/article/PIIS0010945210000298/abstract?rss=yesDuring the last couple of decades we have witnessed the intense development of a fascinating discipline marrying two fields that previously had little overlap: the cognitive psychology and the neuroscience of aging. This new discipline is the cognitive neuroscience of aging, which focuses on the relationships between the age effects on behavioural measures such as accuracy and speed data from attention, memory or executive function tasks and age effects on the brain assessed through neuroimaging (). The collection of research articles assembled in this special issue address some of the most recent issues investigated using this combination of behavioural and neuroimaging methods. A range of neuroimaging techniques [Functional Magnetic Resonance Imaging (fMRI), Event Related Potentials (ERPs) and Diffusion Tensor Imaging (DTI)] are used to explore age effects on a number of cognitive tasks ranging from attention and passive listening to memory and executive function. The rich results from these studies indicate that we have moved well beyond a simple ‘frontal lobe model’ of cognitive aging to one which considers the connectivity between multiple brain regions. Another important issue addressed here is the multidirectional interplay between cognitive and neural functioning, often discussed in terms of compensatory mechanisms.The cognitive neuroscience of aging: New findings on compensation and connectivityLouise H. Phillips, Pilar Andrés10.1016/j.cortex.2010.01.005Cortex 46, 4 (2010)2010-02-04Cortex2010-02-04464S0010-9452(10)X0003-XEditorial421424http://www.cortexjournal.net/article/PIIS001094520900152X/abstract?rss=yesAbstract: Introduction: Older adults often show sustained attention toward positive information and an improved memory for positive events. Little is known about the neural changes that may underlie these effects, although recent research has suggested that older adults may show differential recruitment of prefrontal regions during the successful encoding of emotional information. In the present study, effective connectivity analyses examined the network of regions that college-age and older adults recruited during the encoding of positive and negative images.Methods: Participants viewed positive and negative images while undergoing a functional magnetic resonance imaging (fMRI) scan. Structural equation modeling was used to compare young and older adults' connectivity among regions of the emotional memory network while they encoded negative or positive items.Results: Aging did not impact the connectivity among regions engaged during the encoding of negative information, but age differences did arise during the encoding of positive information. Most notably, in older adults, the ventromedial prefrontal cortex and amygdala strongly influenced hippocampal activity during the encoding of positive information. By contrast, in young adults, a strong thalamic influence on hippocampal activity was evident during encoding.Conclusions: These findings suggest that older adults' “positivity effect” may arise from age-related changes in the interactions between affect-processing regions and the hippocampus during the encoding of positive information.There are age-related changes in neural connectivity during the encoding of positive, but not negative, informationDonna R. Addis, Christina M. Leclerc, Keely A. Muscatell, Elizabeth A. Kensinger10.1016/j.cortex.2009.04.011Cortex 46, 4 (2010)2009-06-26Cortex2009-06-26464S0010-9452(10)X0003-XResearch Reports425433http://www.cortexjournal.net/article/PIIS0010945209002755/abstract?rss=yesAbstract: This study aimed to explore the combined influence of age and cognitive control on the behavioural and electrophysiological indicators of local, restart and mixing costs. Two groups of middle-aged (49–60y.o., N=40) and older (61–80y.o., N=40) adults were split according to their overall z-score in a composite of six neuropsychological measures of executive function. All participants performed a task-cueing version of the Wisconsin Card Sorting Test (WCST) adapted for measuring event-related potentials, whereby tonal cues instructed to switch or repeat the task rule. A single-task condition with identical sensory and motor response demands was used to aid interpretation of behavioural and brain responses to cues and target events. Working memory updating of stimulus–response mappings, as putatively indexed by local switch costs and cue-locked P3 activity (350–460msec post-cue onset), was preserved in both older and low control adults. In turn, low control adults showed larger restart costs and enhanced cue-locked P2 amplitudes (190–250msec) in the task-switching condition only, suggesting lesser preparatory control in the presence of interference. Low control adults showed comparatively larger mixing costs and smaller cue-locked fronto-central slow negativities (500–700msec), suggesting an inefficient online maintenance of task-set information over time. In contrast, target-locked brain responses were mostly sensitive to age-related effects, with older adults showing two well-known effects: (1) an “anterior shift” in target P3 activity (350–460msec), and (2) an attenuation of fronto-central slow negativities in single-task and task-switching conditions, respectively. The additive association found between age and cognitive control for different behavioural indexes of task-switch costs suggests a differential influence of these factors upon two successive information processing stages: individual differences in cognitive control mainly influenced the neural indexes of preparatory task-set activation and maintenance, whereas age-related effects influenced the neural indexes of target response selection and task execution.Individual differences in aging and cognitive control modulate the neural indexes of context updating and maintenance during task switchingDaniel Adrover-Roig, Francisco Barceló10.1016/j.cortex.2009.09.012Cortex 46, 4 (2010)2009-11-05Cortex2009-11-05464S0010-9452(10)X0003-XResearch Reports434450http://www.cortexjournal.net/article/PIIS0010945209001579/abstract?rss=yesAbstract: Introduction: Cognitive reserve (CR) reflects the capacity of the brain to endure neuropathology in order to minimize clinical manifestations. Previous studies showed that CR modulates the patterns of brain activity in both healthy and clinical populations. In the present study we sought to determine whether reorganizations of functional brain resources linked to CR could already be observed in amnestic mild cognitive impairment (a-MCI) and mild Alzheimer's disease (AD) patients when performing a task corresponding to an unaffected cognitive domain. We further investigated if activity in regions showing task-induced deactivations, usually identified as pertaining to the default-mode network (DMN), was also influenced by CR.Methods: Fifteen healthy elders, 15 a-MCI and 15 AD patients underwent functional magnetic resonance imaging (fMRI) during a speech comprehension task. Differences in the regression of slopes between CR proxies and blood-oxygen-level dependent (BOLD) signals across clinical groups were investigated for activation and deactivation areas. Correlations between significant fMRI results and a language comprehension test were also computed.Results: Among a-MCI and AD we observed positive correlations between CR measures and BOLD signals in task-induced activation areas directly processing speech, as well as greater deactivations in regions of the DMN. These relationships were inverted in healthy elders. We found no evidence that these results were mediated by gray matter volumes. Increased activity in left frontal areas and decreased activity in the anterior cingulate were related to better language comprehension in clinical evaluations.Conclusions: The present findings provide evidence that the neurofunctional reorganizations related to CR among a-MCI and AD patients can be seen even when considering a preserved cognitive domain, being independent of gray matter atrophy. Areas showing both task-induced activations and deactivations are modulated by CR in an opposite manner when considering healthy elders versus patients. Brain reorganizations facilitated by CR may reflect behavioral compensatory mechanisms.Cognitive reserve modulates task-induced activations and deactivations in healthy elders, amnestic mild cognitive impairment and mild Alzheimer's diseaseBeatriz Bosch, David Bartrés-Faz, Lorena Rami, Eider M. Arenaza-Urquijo, Davinia Fernández-Espejo, Carme Junqué, Cristina Solé-Padullés, Raquel Sánchez-Valle, Núria Bargalló, Carles Falcón, José Luis Molinuevo10.1016/j.cortex.2009.05.006Cortex 46, 4 (2010)2009-06-29Cortex2009-06-29464S0010-9452(10)X0003-XResearch Reports451461http://www.cortexjournal.net/article/PIIS001094520900327X/abstract?rss=yesAbstract: Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies have revealed age-related under-activation, where older adults show less regional brain activation compared to younger adults, as well as age-related over-activation, where older adults show greater activation compared to younger adults. These differences have been found across multiple task domains, including verbal working memory (WM). Curiously, both under-activation and over-activation of dorsolateral prefrontal cortex (DLPFC) have been found for older adults in verbal WM tasks. Here, we use event-related fMRI to test the hypothesis that age-related differences in activation depend on memory load (the number of items that must be maintained). Our predictions about the recruitment of prefrontal executive processes are based on the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH; ). According to this hypothesis, more neural resources are engaged by older brains to accomplish computational goals completed with fewer resources by younger brains. Therefore, seniors are more likely than young adults to show over-activations at lower memory loads, and under-activations at higher memory loads. Consistent with these predictions, in right DLPFC, we observed age-related over-activation with lower memory loads despite equivalent performance accuracy across age groups. In contrast, with the highest memory load, older adults were significantly less accurate and showed less DLPFC activation compared to their younger counterparts. These results are considered in relation to previous reports of activation–performance relations using similar tasks, and are found to support the viability of CRUNCH as an account of age-related compensation and its potential costs.Age differences in prefontal recruitment during verbal working memory maintenance depend on memory loadKatherine A. Cappell, Leon Gmeindl, Patricia A. Reuter-Lorenz10.1016/j.cortex.2009.11.009Cortex 46, 4 (2010)2010-01-25Cortex2010-01-25464S0010-9452(10)X0003-XResearch Reports462473http://www.cortexjournal.net/article/PIIS0010945209002202/abstract?rss=yesAbstract: Introduction: Previous studies by our group have found that white matter integrity as determined by Diffusion Tensor Imaging (DTI) is associated with working memory decline. It has been proposed that subtle white matter integrity loss may lead to the disruption of working memory in particular because it relies on the dynamic and reiterative activity of cortico-cortical pathways.Methods: DTI and working memory measurement were acquired for 99 adults from our GENIE study of healthy middle aged and elderly individuals. Voxel-based statistics were used to identify clusters of voxels in mean diffusivity images specifically associated with variations in working memory performance. Tractography then identified the cortico-cortical white matter pathways passing through these clusters, between the temporal, parietal and frontal cortices.Results: Significant clusters were identified which were associated with working memory in the white matter of the temporal and frontal lobes, the cingulate gyrus, and in the thalamus. The tracts that passed through these clusters included the superior parietal lobule pathway, the medial temporo-frontal pathway, the uncinate fasciculus, the fronto-parietal fasciculus, and the cingulum.Conclusions: Significant clusters were identified in the white matter that were associated with working memory performance. Tractography performed through these clusters identified white matter fiber tracts which pass between grey matter regions known to be activated by working memory tasks and also mirror working memory pathways suggested by previous functional connectivity imaging.White matter pathways associated with working memory in normal agingRebecca A. Charlton, Thomas R. Barrick, I. Nigel C. Lawes, Hugh S. Markus, Robin G. Morris10.1016/j.cortex.2009.07.005Cortex 46, 4 (2010)2009-08-10Cortex2009-08-10464S0010-9452(10)X0003-XResearch Reports474489http://www.cortexjournal.net/article/PIIS0010945209001610/abstract?rss=yesAbstract: In an event-related functional Magnetic Resonance Imaging (fMRI) study, younger and older adults were presented with negative emotional (i.e., fearful) and neutral face pictures under incidental learning conditions. They were subsequently given a test of face recognition outside the scanner. Both age groups activated amygdala bilaterally as well as the right hippocampus during successful encoding of the fearful faces. Direct age comparisons revealed greater activation in right amygdala and bilateral hippocampus in the young, whereas older adults showed greater activation in the left insular and right prefrontal cortices. None of these brain areas was activated during successful encoding of neutral faces, suggesting specificity of these brain activation patterns. The results indicate an age-related shift in the neural underpinnings of negative emotional face processing from medial–temporal to neocortical regions.Age-related differences in brain regions supporting successful encoding of emotional facesHåkan Fischer, Lars Nyberg, Lars Bäckman10.1016/j.cortex.2009.05.011Cortex 46, 4 (2010)2009-06-29Cortex2009-06-29464S0010-9452(10)X0003-XResearch Reports490497http://www.cortexjournal.net/article/PIIS0010945209001567/abstract?rss=yesAbstract: We used event-related potentials to investigate how aging affects local contextual processing. Local context was defined as the occurrence of a short predictive series of visual stimuli before delivery of a target event. Stimuli were presented to either the left or right visual field and consisted of 15% targets (downward facing triangle) and 85% of equal numbers of three types of standards (triangles facing left, upwards and right). Recording blocks consisted of targets preceded by either randomized sequences of standards or by sequences including a three-standard predictive sequence signaling the occurrence of a subsequent target event. Subjects pressed a button in response to targets. Predictive local context affected target detection by reducing the duration of stimulus evaluation compared to detection of non-predictive random targets comparably for both young and older adults, as shown by a P3b latency shift. The peak of an earlier latency context positivity, which was seen only in the predicted compared to the random target condition, was prolonged in the older population compared to young adults. Finally, older subjects elicited a late sustained positivity in the predictive condition, not seen in the younger subjects. Taken together, these findings suggest that local contextual effects on target detection processes are altered with age.Electrophysiological evidence for aging effects on local contextual processingNoa Fogelson, Mona Shah, Frederique Bonnet-Brilhault, Robert T. Knight10.1016/j.cortex.2009.05.007Cortex 46, 4 (2010)2009-06-26Cortex2009-06-26464S0010-9452(10)X0003-XResearch Reports498506http://www.cortexjournal.net/article/PIIS0010945209002251/abstract?rss=yesAbstract: In the present study, we manipulated the cognitive effort in an associative encoding task using functional magnetic resonance imaging (fMRI). Older and younger adults were presented with two objects that were either semantically related or unrelated, and were required to form a relationship between the items. Both groups self-reported greater difficulty in completing the unrelated associative encoding task providing independent evidence of the associative difficulty manipulation. On both the low and high difficulty tasks, older adults showed a typical pattern of increased right inferior frontal recruitment relative to younger adults. Of particular interest was the finding that both groups showed increased activation as task difficulty increased in the left inferior frontal gyrus and left hippocampus. Overall, the results suggest that the aging brain is characterized by greater prefrontal processing, but that as cognitive demand increases, the networks used by older and younger adults are the largely the same.The impact of increased relational encoding demands on frontal and hippocampal function in older adultsEric D. Leshikar, Angela H. Gutchess, Andrew C. Hebrank, Bradley P. Sutton, Denise C. Park10.1016/j.cortex.2009.07.011Cortex 46, 4 (2010)2009-08-27Cortex2009-08-27464S0010-9452(10)X0003-XResearch Reports507521http://www.cortexjournal.net/article/PIIS0010945209002652/abstract?rss=yesAbstract: In this event-related evoked potentials (ERP) study, the neural correlates of a group of highly educated older adults were compared with those of a group of young adults while performing a word-stem completion priming task under semantic and lexical encoding conditions. The results revealed that both age groups exhibited robust priming. The older participants showed better performance than the young adults. Both groups exhibited ERP repetition effects at posterior sites, but only the older adults showed additional frontal activity. The results suggest that highly performing older adults compensate for their lower level of parieto-occipital functioning, reflected by smaller P300 amplitude at posterior sites, by recruiting frontal sites as a mode of brain adaptation.Ageing affects brain activity in highly educated older adults: An ERP study using a word-stem priming taskAlexandra Osorio, Séverine Fay, Viviane Pouthas, Soledad Ballesteros10.1016/j.cortex.2009.09.003Cortex 46, 4 (2010)2009-10-08Cortex2009-10-08464S0010-9452(10)X0003-XResearch Reports522534http://www.cortexjournal.net/article/PIIS0010945209002196/abstract?rss=yesAbstract: Aging is associated with decrements in both spatial and temporal context retrieval. Functional neuroimaging studies of young adults suggest that there are differences in left versus right lateral prefrontal cortex (PFC) contributions to spatial versus temporal source (recency) retrieval, respectively. The goal of the current study was to determine if age-related decreases in temporal and spatial context retrieval are due to common or distinct changes in PFC function. To address this goal we conducted an event-related functional magnetic resonance imaging (fMRI) study in which young and older adults performed recognition, recency and spatial context retrieval tasks using face stimuli to identify event-related PFC regions associated with these retrieval tasks in both age groups. Our behavioural results indicated that older adults did not differ on recognition performance, but did exhibit a deficit in both context retrieval tasks, compared to young adults. The fMRI results suggest that age-related deficits in both spatial and temporal context retrieval may be linked to functional changes in right dorsolateral and left medial anterior PFC (APFC) function. In addition, based on brain-behaviour correlations in older adults, our results imply that older adults attempt to compensate for these deficits by engaging left dorsolateral PFC during spatial context retrieval and right APFC during temporal context retrieval.Age-related changes in prefrontal cortex activity are associated with behavioural deficits in both temporal and spatial context memory retrieval in older adultsM. Natasha Rajah, Rafael Languay, Luc Valiquette10.1016/j.cortex.2009.07.006Cortex 46, 4 (2010)2009-08-12Cortex2009-08-12464S0010-9452(10)X0003-XResearch Reports535549http://www.cortexjournal.net/article/PIIS0010945209002433/abstract?rss=yesAbstract: Studies examining the effects of aging in the oddball task have consistently revealed an age-related change in the topography of the P3 component. Specifically, in younger adults the amplitude of this component is greatest over the parietal region of the scalp while in older adults the P3 is more evenly distributed over the parietal and frontal regions of the scalp. In the current study, Partial Least Squares (PLS) analysis was used to examine the effects of age on the full time course and topography of the event-related brain potentials (ERPs) elicited during the oddball task; and to consider the influence of individual differences in executive function on age-related differences in the oddball task. Aging and individual differences appeared to have relatively little effect on the P3b that distinguished oddball stimulus from standards. The age-related “anterior shift” in the P3 appeared to result from the stronger expression of the novelty P3 in older adults relative to younger adults, as this effect was seen for both oddball and novel stimuli relative to standard stimuli. Additionally, the effect of age interacted with variation in executive function, with the novelty P3 being elicited for novel and oddball stimuli in the low executive older adults and only for novel stimuli in the high executive older adults. These findings lead to the suggestion that the age-related anterior shift in the P3 may result from the failure of older adults with lower executive functions to habituate to the oddball stimulus.The influence of age and individual differences in executive function on stimulus processing in the oddball taskRobert West, Hillary Schwarb, Brandy N. Johnson10.1016/j.cortex.2009.08.001Cortex 46, 4 (2010)2009-09-01Cortex2009-09-01464S0010-9452(10)X0003-XResearch Reports550563http://www.cortexjournal.net/article/PIIS0010945209002457/abstract?rss=yesAbstract: Our ability to focus attention on task-relevant stimuli and ignore irrelevant distractions is reflected by differential enhancement and suppression of neural activity in sensory cortices. Previous research has shown that older adults exhibit a deficit in suppressing task-irrelevant information, the magnitude of which is associated with a decline in working memory performance. However, it remains unclear if a failure to suppress is a reflection of an inability of older adults to rapidly assess the relevance of information upon stimulus presentation when they are not aware of the relevance beforehand. To address this, we recorded the electroencephalogram (EEG) in healthy older participants (aged 60—80 years) while they performed two different versions of a selective face/scene working memory task, both with and without prior knowledge as to when relevant and irrelevant stimuli would appear. Each trial contained two faces and two scenes presented sequentially followed by a 9sec delay and a probe stimulus. Participants were given the following instructions: remember faces (ignore scenes), remember scenes (ignore faces), remember the xth and yth stimuli (where x and y could be 1st, 2nd, 3rd or 4th), or passively view all stimuli. Working memory performance remained consistent regardless of task instructions. Enhanced neural activity was observed at posterior electrodes to attended stimuli, while neural responses that reflected the suppression of irrelevant stimuli was absent for both tasks. The lack of significant suppression at early stages of visual processing was revealed by P1 amplitude and N1 latency modulation indices. These results reveal that prior knowledge of stimulus relevance does not modify early neural processing during stimulus encoding and does not improve working memory performance in older adults. These results suggest that the inability to suppress irrelevant information early in the visual processing stream by older adults is related to mechanisms specific to top-down suppression.Predictive knowledge of stimulus relevance does not influence top-down suppression of irrelevant information in older adultsTheodore P. Zanto, Kelly Hennigan, Mattias Östberg, Wesley C. Clapp, Adam Gazzaley10.1016/j.cortex.2009.08.003Cortex 46, 4 (2010)2009-09-11Cortex2009-09-11464S0010-9452(10)X0003-XResearch Reports564574http://www.cortexjournal.net/article/PIIS0010945209002731/abstract?rss=yesAbstract: Introduction: Forming an intention is a key aspect of prospective memory, i.e., the ability to encode, retain, and later realize an intention with a delay of minutes, hours or days. Behavioural and neurophysiological findings from both prospective and retrospective memory research suggest that the efficiency of encoding processes is reduced at both ends of the lifespan and that neural generators underlying successful encoding might differ in childhood and old age. Hence, the present study investigates compensational neural mechanisms during the encoding of intentions in adolescents and old adults compared to young adults.Methods: We compared Event-Related Potentials (ERPs) and their source localization in 14 adolescents (11–13 years), 14 young adults (18–25 years), and 14 old adults (64–79 years) in a prospective memory task that was embedded in a semantic categorization task.Results: Our data revealed three event-related modulations that differentiate between conditions (i.e., ongoing activity and successful intention formation trials) and groups. Source localizations of these modulations with standardized low-resolution electromagnetic tomography (sLORETA) revealed compensational activations in adolescents and old adults compared to young adults in successful intention formation trials: while adolescents showed a higher activation of secondary occipital regions in the time window of 500–1200msec with a maximum around 800msec, old adults activated prefrontal regions to a greater extent beginning at 700msec, persisting until 1200msec and expanding to middle temporal regions.Conclusion: For a successful encoding of intentions adolescents and old adults recruit more neural generators than young adults. More importantly, the pattern of these compensational activations is different when comparing adolescents with young adults and old adults with young adults. These differences are discussed with regard to differential maturational changes in the brain.Forming intentions successfully: Differential compensational mechanisms of adolescents and old adultsJacqueline Zöllig, Mike Martin, Matthias Kliegel10.1016/j.cortex.2009.09.010Cortex 46, 4 (2010)2009-10-30Cortex2009-10-30464S0010-9452(10)X0003-XResearch Reports575589