551
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Subjective aspects of cognitive control at different stages of processing. Atten Percept Psychophys 2010; 71:1807-24. [PMID: 19933564 DOI: 10.3758/app.71.8.1807] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although research on cognitive control has addressed the effects that different forms of cognitive interference have on behavior and the activities of certain brain regions, until recently, the effects of interference on subjective experience have not been addressed. We demonstrate that, at the level of the individual trial, participants can reliably introspect the subjective aspects (e.g., perceptions of difficulty, competition, and control) of responding in interference paradigms. Similar subjective effects were obtained for both expressed and unexpressed (subvocalized) actions. Few participants discerned the source of these effects. These basic findings illuminate aspects of cognitive control and cognitive effort. In addition, these data have implications for the study of response interference in affect and self-control, and they begin to address theories regarding the function of consciousness.
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552
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Johnson MR, Johnson MK. Top-down enhancement and suppression of activity in category-selective extrastriate cortex from an act of reflective attention. J Cogn Neurosci 2010; 21:2320-7. [PMID: 19199413 DOI: 10.1162/jocn.2008.21183] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Recent research has demonstrated top-down attentional modulation of activity in extrastriate category-selective visual areas while stimuli are in view (perceptual attention) and after they are removed from view (reflective attention). Perceptual attention is capable of both enhancing and suppressing activity in category-selective areas relative to a passive viewing baseline. In this study, we demonstrate that a brief, simple act of reflective attention ("refreshing") is also capable of both enhancing and suppressing activity in some scene-selective areas (the parahippocampal place area [PPA]) but not others (refreshing resulted in enhancement but not in suppression in the middle occipital gyrus [MOG]). This suggests that different category-selective extrastriate areas preferring the same class of stimuli may contribute differentially to reflective processing of one's internal representations of such stimuli.
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Affiliation(s)
- Matthew R Johnson
- Department of Psychology, Yale University, New Haven, CT 06520-8205, USA.
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553
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Wang L, Li Y, Metzak P, He Y, Woodward TS. Age-related changes in topological patterns of large-scale brain functional networks during memory encoding and recognition. Neuroimage 2010; 50:862-72. [PMID: 20093190 DOI: 10.1016/j.neuroimage.2010.01.044] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 12/18/2009] [Accepted: 01/13/2010] [Indexed: 11/26/2022] Open
Abstract
In this study we used functional magnetic resonance imaging to investigate age-related changes in large-scale brain functional networks during memory encoding and recognition in 12 younger and 16 older adults. For each participant, functional brain networks were constructed by computing temporal correlation matrices of 90 brain regions and analyzed using graph theoretical approaches. We found the age-related changes mainly in the long-range connections with widespread reductions associated with aging in the fronto-temporal and temporo-parietal regions, and a few age-related increases in the posterior parietal regions. Graph theoretical analysis revealed that the older adults had longer path lengths linking different regions in the functional brain networks as compared to the younger adults. Further analysis indicated that the increases in shortest path length in the networks were combined with the loss of long-range connections. Finally, we showed that for older adults, frontal areas played reduced roles in the network (reduced regional centrality), whereas several default-mode regions played increased roles relative to younger subjects (increased regional centrality). Together, our results suggest that normal aging is associated with disruption of large-scale brain systems during the performance of memory tasks, which provides novel insights into the understanding of age-related decline in multiple cognitive functions.
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Affiliation(s)
- Liang Wang
- Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada
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554
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Chen Q, Fuentes LJ, Zhou X. Biasing the organism for novelty: A pervasive property of the attention system. Hum Brain Mapp 2010; 31:1146-56. [PMID: 20063302 DOI: 10.1002/hbm.20924] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Although the functional and anatomical independences between the orienting and the executive attention networks have been well established, surprisingly little is known about the potential neural interaction between them. Recent studies point out that spatial inhibition of return (IOR), a mechanism associated with the orienting network, and nonspatial inhibition of return, a mechanism associated with the executive network, might bias the organism for novel locations and objects, respectively. By orthogonally combining the spatial and the nonspatial IOR paradigms in this fMRI study, we demonstrate that the orienting and the executive networks interact and compensate each other in biasing the attention system for novelty. Behaviorally, participants responded slower to the target at the old location only when the color of the target was novel, and participants responded slower to the old color representation only when the target appeared at a novel spatial location. Neurally, the orienting network was involved in slowing down responses to the old location only when the nonspatial IOR mechanism in the executive network was not operative (i.e., when the color of the target was novel); the prefrontal executive network was involved in slowing down responses to the old color representation only when the spatial IOR mechanism in the orienting network was not functioning (i.e., when the target appeared at a novel location).
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Affiliation(s)
- Qi Chen
- Center for Studies of Psychological Application, South China Normal University, Guangzhou, China
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555
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Wild-Wall N, Falkenstein M. Age-dependent impairment of auditory processing under spatially focused and divided attention: An electrophysiological study. Biol Psychol 2010; 83:27-36. [DOI: 10.1016/j.biopsycho.2009.09.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 09/22/2009] [Accepted: 09/22/2009] [Indexed: 11/28/2022]
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556
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Kayser AS, Buchsbaum BR, Erickson DT, D'Esposito M. The functional anatomy of a perceptual decision in the human brain. J Neurophysiol 2009; 103:1179-94. [PMID: 20032247 DOI: 10.1152/jn.00364.2009] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our ability to make rapid decisions based on sensory information belies the complexity of the underlying computations. Recently, "accumulator" models of decision making have been shown to explain the activity of parietal neurons as macaques make judgments concerning visual motion. Unraveling the operation of a decision-making circuit, however, involves understanding both the responses of individual components in the neural circuitry and the relationships between them. In this functional magnetic resonance imaging study of the decision process in humans, we demonstrate that an accumulator model predicts responses to visual motion in the intraparietal sulcus (IPS). Significantly, the metrics used to define responses within the IPS also reveal distinct but interacting nodes in a circuit, including early sensory detectors in visual cortex, the visuomotor integration system of the IPS, and centers of cognitive control in the prefrontal cortex, all of which collectively define a perceptual decision-making network.
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Affiliation(s)
- Andrew S Kayser
- Helen Wills Neuroscience Institute, 132 Barker Hall, University of California at Berkeley, Berkeley, CA 94720, USA.
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557
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Bidet-Caulet A, Mikyska C, Knight RT. Load effects in auditory selective attention: evidence for distinct facilitation and inhibition mechanisms. Neuroimage 2009; 50:277-84. [PMID: 20026231 DOI: 10.1016/j.neuroimage.2009.12.039] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 12/02/2009] [Accepted: 12/08/2009] [Indexed: 10/20/2022] Open
Abstract
It is unknown whether facilitation and inhibition of stimulus processing represent one or two mechanisms in auditory attention. We performed electrophysiological experiments in humans to address these two competing hypothesis. Participants performed an attention task under low or high memory load. Facilitation and inhibition were measured by recording electrophysiological responses to attended and ignored sounds and comparing them to responses to these same sounds when attention was considered to be equally distributed towards all sounds. We observed two late frontally distributed components: a negative one in response to attended sounds, and a positive one to ignored sounds. These two frontally distributed responses had distinct timing and scalp topographies and were differentially affected by memory load. Taken together these results provide evidence that attention-mediated top-down control reflects the activity of distinct facilitation and inhibition mechanisms.
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Affiliation(s)
- Aurélie Bidet-Caulet
- Helen Wills Neuroscience Institute, University of California, Berkeley, 132 Barker Hall, Berkeley, CA 94720, USA.
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558
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Stevens WD, Buckner RL, Schacter DL. Correlated low-frequency BOLD fluctuations in the resting human brain are modulated by recent experience in category-preferential visual regions. ACTA ACUST UNITED AC 2009; 20:1997-2006. [PMID: 20026486 DOI: 10.1093/cercor/bhp270] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The resting brain is associated with significant intrinsic activity fluctuations, such as the correlated low-frequency (LF) blood oxygen level-dependent (BOLD) fluctuations measured by functional magnetic resonance imaging. Despite a recent expansion of studies investigating resting-state LF-BOLD correlations, their nature and function are poorly understood. A major constraint on LF-BOLD correlations appears to be stable properties of anatomic connectivity. There is also evidence that coupling can be modulated by recent or ongoing task performance, suggesting that certain components of correlated dynamics are malleable on short timescales. Here, we compared activity during extended periods of rest following performance of 2 distinct cognitive tasks using different categories of visual stimuli-faces and complex scenes. Prolonged exposure to these distinct categories of visual information caused frontal networks to couple differentially with posterior category-preferential visual regions during subsequent periods of rest. In addition, we report preliminary evidence suggesting that conditions exist in which the degree of modulation of LF-BOLD correlations predicts subsequent memory. The finding that resting-state LF-BOLD correlations are modulated by recent experience in functionally specific brain regions engaged during prior task performance clarifies their role as a dynamic phenomenon which may be involved in mnemonic processes.
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Affiliation(s)
- W Dale Stevens
- Department of Psychology, Harvard University, Cambridge, MA 02138, USA
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559
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Morsella E, Lanska M, Berger CC, Gazzaley A. Indirect cognitive control through top-down activation of perceptual symbols. EUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY 2009. [DOI: 10.1002/ejsp.679] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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560
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Van Snellenberg JX. Working memory and long-term memory deficits in schizophrenia: is there a common substrate? Psychiatry Res 2009; 174:89-96. [PMID: 19837568 DOI: 10.1016/j.pscychresns.2009.04.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Revised: 04/09/2009] [Accepted: 04/15/2009] [Indexed: 12/19/2022]
Abstract
Patients with schizophrenia exhibit substantial deficits in both working memory (WM) and long-term memory (LTM) tasks. While these two forms of memory are generally viewed as distinct, recent evidence from healthy subjects has challenged the robustness of the double-dissociation between these two types of memory. In light of an emerging view of WM and LTM as being subserved by a largely overlapping network of brain regions, it is possible that WM and LTM deficits in patients with schizophrenia share a common neurobiological substrate. This review revisits the functional neuroimaging literature on both WM and LTM in patients with schizophrenia with these considerations in mind, and reveals a number of commonalities in research findings in both literatures. While there is a paucity of direct evidence bearing on whether patient deficits in these tasks arise from a common functional abnormality, the available literature is consistent with the hypothesis that these deficits have the same origin.
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561
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Wood G, Ischebeck A, Koppelstaetter F, Gotwald T, Kaufmann L. Developmental trajectories of magnitude processing and interference control: an FMRI study. Cereb Cortex 2009; 19:2755-65. [PMID: 19357393 PMCID: PMC2853708 DOI: 10.1093/cercor/bhp056] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neurodevelopmental changes regarding interference and magnitude processing were assessed in 3 age groups (children, n = 10; young adults, n = 11; elderly participants, n = 9) by using an functional magnetic resonance imaging version of the numerical Stroop task. Behaviorally, comparable distance and size congruity effects were found in all 3 age groups. Distance effects were most pronounced in the more difficult numerical task, whereas size congruity effects were comparable across tasks. In response to interference, an age-linear trend in the pattern of activation in left and right prefrontal and left middle temporal regions of the brain was observed. This implicates that with increasing age interference control requires increasing effort (possible explanations for children's relatively lower interference effects are provided). In contrast, the distance effect produced a negative linear trend in right prefrontal, supplementary motor area, and intraparietal cortex. This suggests that relative to old adults, children and young adults had to recruit a larger network upon processing magnitude. The latter findings are even more remarkable considering that the behavioral effects were similar across groups. In summary, the developmental trajectories of interference control and magnitude processing differ, although these cognitive functions activate partially overlapping brain regions.
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Affiliation(s)
- Guilherme Wood
- Department of Psychology, University of Salzburg, A-5020 Salzburg, Austria.
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562
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Jimura K, Braver TS. Age-related shifts in brain activity dynamics during task switching. ACTA ACUST UNITED AC 2009; 20:1420-31. [PMID: 19805420 DOI: 10.1093/cercor/bhp206] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cognitive aging studies have suggested that older adults show declines in both sustained and transient cognitive control processes. However, previous neuroimaging studies have primarily focused on age-related change in the magnitude, but not temporal dynamics, of brain activity. The present study compared brain activity dynamics in healthy old and young adults during task switching. A mixed blocked/event-related functional magnetic resonance imaging design enabled separation of transient and sustained neural activity associated with cognitive control. Relative to young adults, older adults exhibited not only decreased sustained activity in the anterior prefrontal cortex (aPFC) during task-switching blocks but also increased transient activity on task-switch trials. Another pattern of age-related shift in dynamics was present in the lateral PFC (lPFC) and posterior parietal cortex (PPC), with younger adults showing a cue-related response during task-switch trials in lPFC and PPC, whereas older adults exhibited switch-related activation during the cue period in PPC only. In all 3 regions, these qualitatively distinct patterns of brain activity predicted qualitatively distinct patterns of behavioral performance across the 2 age groups. Together, these results suggest that older adults may shift from a proactive to reactive cognitive control strategy as a means of retaining relatively preserved behavioral performance in the face of age-related neurocognitive changes.
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Affiliation(s)
- Koji Jimura
- Department of Psychology, Washington University in St Louis, St Louis, MO 63139, USA.
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563
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Harris KC, Eckert MA, Ahlstrom JB, Dubno JR. Age-related differences in gap detection: effects of task difficulty and cognitive ability. Hear Res 2009; 264:21-9. [PMID: 19800958 DOI: 10.1016/j.heares.2009.09.017] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 09/28/2009] [Accepted: 09/30/2009] [Indexed: 10/20/2022]
Abstract
Differences in gap detection for younger and older adults have been shown to vary with the complexity of the task or stimuli, but the factors that contribute to these differences remain unknown. To address this question, we examined the extent to which age-related differences in processing speed and workload predicted age-related differences in gap detection. Gap detection thresholds were measured for 10 younger and 11 older adults in two conditions that varied in task complexity but used identical stimuli: (1) gap location fixed at the beginning, middle, or end of a noise burst and (2) gap location varied randomly from trial to trial from the beginning, middle, or end of the noise. We hypothesized that gap location uncertainty would place increased demands on cognitive and attentional resources and result in significantly higher gap detection thresholds for older but not younger adults. Overall, gap detection thresholds were lower for the middle location as compared to beginning and end locations and were lower for the fixed than the random condition. In general, larger age-related differences in gap detection were observed for more challenging conditions. That is, gap detection thresholds for older adults were significantly larger for the random condition than for the fixed condition when the gap was at the beginning and end locations but not the middle. In contrast, gap detection thresholds for younger adults were not significantly different for the random and fixed condition at any location. Subjective ratings of workload indicated that older adults found the gap detection task more mentally demanding than younger adults. Consistent with these findings, results of the Purdue Pegboard and Connections tests revealed age-related slowing of processing speed. Moreover, age group differences in workload and processing speed predicted gap detection in younger and older adults when gap location varied from trial to trial; these associations were not observed when gap location remained constant across trials. Taken together, these results suggest that age-related differences in complex measures of auditory temporal processing may be explained, in part, by age-related deficits in processing speed and attention.
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Affiliation(s)
- Kelly C Harris
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Ave., MSC 550, Charleston, SC 29425-5500, USA.
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564
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Oei NYL, Tollenaar MS, Spinhoven P, Elzinga BM. Hydrocortisone reduces emotional distracter interference in working memory. Psychoneuroendocrinology 2009; 34:1284-93. [PMID: 19398277 DOI: 10.1016/j.psyneuen.2009.03.015] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 03/06/2009] [Accepted: 03/23/2009] [Indexed: 10/20/2022]
Abstract
Several studies have shown that stress and glucocorticoids can impair prefrontal-dependent working memory (WM) performance. WM is the ability to attend to the task at hand, and to maintain relevant information in mind during a delay while ignoring irrelevant stimuli. Here, it is investigated whether stress hormones impair WM by reducing the ability to suppress distracting, irrelevant neutral and emotional stimuli. Hydrocortisone (35 mg) (n=23) or placebo (n=21) was administered to young, healthy men, who performed a Sternberg WM task with neutral and emotional irrelevant distracters shown in the delay-phase of the task, between encoding and recognition of the relevant stimuli for WM. Contrary to expectations, enhanced WM performance with higher processing speed and a reduction of errors was found in the hydrocortisone group compared to placebo. Moreover, hydrocortisone significantly reduced the distraction by emotional stimuli. These findings show that cortisol effects on WM are not unambiguous and contrast with previous findings on the impairing effects of cortisol on WM. Dose-response studies could give more insight into the specific modulating effects of glucocorticoids on suppression of irrelevant emotional distraction.
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Affiliation(s)
- Nicole Y L Oei
- Leiden University - Institute for Psychological Research, 2300 RB Leiden, The Netherlands.
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565
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Chee MWL, Tan JC, Parimal S, Zagorodnov V. Sleep deprivation and its effects on object-selective attention. Neuroimage 2009; 49:1903-10. [PMID: 19761853 DOI: 10.1016/j.neuroimage.2009.08.067] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 08/14/2009] [Accepted: 08/19/2009] [Indexed: 11/26/2022] Open
Abstract
Sleep deprivation (SD) affects attention but it is an open question as to whether all subtypes of attention are similarly affected. We investigated the effects of 24 h of total SD on object-selective attention. 26 healthy, young adults viewed quartets of alternating faces or place scenes and performed selective judgments on faces only, scenes only or both faces and scenes. Volunteers underwent fMRI following a normal night of sleep and again following approximately 24 h of total sleep deprivation in a counterbalanced fashion. Sleep deprivation resulted in slower and less accurate picture classification as well as poorer recognition memory for scenes. Attention strongly modulated activation in the Parahippocampal Place Area (PPA). Task-related activation in the fronto-parietal cortex and PPA was reduced in SD, but the relative modulation of PPA activation by attention was preserved. Psychophysiological interaction between the left intra-parietal sulcus and the PPA that was clearly present after a normal night of sleep was reduced below threshold following SD suggesting that PPI may be a more sensitive method of detecting change in selective attention. Sleep deprivation may affect object-selective attention in addition to exerting a task-independent deficit in attention.
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Affiliation(s)
- Michael W L Chee
- Cognitive Neuroscience Laboratory, Duke-NUS Graduate Medical School, Singapore.
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566
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Zanto TP, Hennigan K, Ostberg M, Clapp WC, Gazzaley A. Predictive knowledge of stimulus relevance does not influence top-down suppression of irrelevant information in older adults. Cortex 2009; 46:564-74. [PMID: 19744649 DOI: 10.1016/j.cortex.2009.08.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Revised: 05/02/2009] [Accepted: 08/05/2009] [Indexed: 11/24/2022]
Abstract
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 9 sec 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.
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Affiliation(s)
- Theodore P Zanto
- Department of Neurology, University of California San Francisco, CA, USA
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567
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Clapp WC, Rubens MT, Gazzaley A. Mechanisms of working memory disruption by external interference. Cereb Cortex 2009; 20:859-72. [PMID: 19648173 DOI: 10.1093/cercor/bhp150] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The negative impact of external interference on working memory (WM) performance is well documented; yet, the mechanisms underlying this disruption are not sufficiently understood. In this study, electroencephalogram and functional magnetic resonance imaging (fMRI) data were recorded in separate experiments that each introduced different types of visual interference during a period of WM maintenance: distraction (irrelevant stimuli) and interruption (stimuli that required attention). The data converged to reveal that regardless of the type of interference, the magnitude of processing interfering stimuli in the visual cortex (as rapidly as 100 ms) predicted subsequent WM recognition accuracy for stored items. fMRI connectivity analyses suggested that in the presence of distraction, encoded items were maintained throughout the delay period via connectivity between the middle frontal gyrus and visual association cortex, whereas memoranda were not maintained when subjects were interrupted but rather reactivated in the postinterruption period. These results elucidate the mechanisms of external interference on WM performance and highlight similarities and differences of distraction and multitasking.
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Affiliation(s)
- Wesley C Clapp
- Department of Neurology and Physiology, Keck Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA.
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568
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Hannula H, Neuvonen T, Savolainen P, Hiltunen J, Ma YY, Antila H, Salonen O, Carlson S, Pertovaara A. Increasing top-down suppression from prefrontal cortex facilitates tactile working memory. Neuroimage 2009; 49:1091-8. [PMID: 19643184 DOI: 10.1016/j.neuroimage.2009.07.049] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 07/20/2009] [Accepted: 07/21/2009] [Indexed: 10/20/2022] Open
Abstract
Navigated transcranial magnetic stimulation (TMS) combined with diffusion-weighted magnetic resonance imaging (DW-MRI) and tractography allows investigating functional anatomy of the human brain with high precision. Here we demonstrate that working memory (WM) processing of tactile temporal information is facilitated by delivering a single TMS pulse to the middle frontal gyrus (MFG) during memory maintenance. Facilitation was obtained only with a TMS pulse applied to a location of the MFG with anatomical connectivity to the primary somatosensory cortex (S1). TMS improved tactile WM also when distractive tactile stimuli interfered with memory maintenance. Moreover, TMS to the same MFG site attenuated somatosensory evoked responses (SEPs). The results suggest that the TMS-induced memory improvement is explained by increased top-down suppression of interfering sensory processing in S1 via the MFG-S1 link. These results demonstrate an anatomical and functional network that is involved in maintenance of tactile temporal WM.
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Affiliation(s)
- Henri Hannula
- Neuroscience Unit, Institute of Biomedicine/Physiology, University of Helsinki, Helsinki, Finland
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569
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Berry AS, Zanto TP, Rutman AM, Clapp WC, Gazzaley A. Practice-related improvement in working memory is modulated by changes in processing external interference. J Neurophysiol 2009; 102:1779-89. [PMID: 19587320 DOI: 10.1152/jn.00179.2009] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Working memory (WM) performance is impaired by the presence of external interference. Accordingly, more efficient processing of intervening stimuli with practice may lead to enhanced WM performance. To explore the role of practice on the impact that interference has on WM performance, we studied young adults with electroencephalographic (EEG) recordings as they performed three motion-direction, delayed-recognition tasks. One task was presented without interference, whereas two tasks introduced different types of interference during the interval of memory maintenance: distractors and interruptors. Distractors were to be ignored, whereas interruptors demanded attention based on task instructions for a perceptual discrimination. We show that WM performance was disrupted by both types of interference, but interference-induced disruption abated across a single experimental session through rapid learning. WM accuracy and response time improved in a manner that was correlated with changes in early neural measures of interference processing in visual cortex (i.e., P1 suppression and N1 enhancement). These results suggest practice-related changes in processing interference exert a positive influence on WM performance, highlighting the importance of filtering irrelevant information and the dynamic interactions that exist between neural processes of perception, attention, and WM during learning.
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Affiliation(s)
- Anne S Berry
- Department of Neurology, W. M. Keck Foundation Center for Integrative Neuroscience, University of California, San Francisco, 600 16th St., Genentech Hall, MC2240 Rm. N472J, San Francisco, CA 94158, USA
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570
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Abstract
Attention is a core property of all perceptual and cognitive operations. Given limited capacity to process competing options, attentional mechanisms select, modulate, and sustain focus on information most relevant for behavior. A significant problem, however, is that attention is so ubiquitous that it is unwieldy to study. We propose a taxonomy based on the types of information that attention operates over--the targets of attention. At the broadest level, the taxonomy distinguishes between external attention and internal attention. External attention refers to the selection and modulation of sensory information. External attention selects locations in space, points in time, or modality-specific input. Such perceptual attention can also select features defined across any of these dimensions, or object representations that integrate over space, time, and modality. Internal attention refers to the selection, modulation, and maintenance of internally generated information, such as task rules, responses, long-term memory, or working memory. Working memory, in particular, lies closest to the intersection between external and internal attention. The taxonomy provides an organizing framework that recasts classic debates, raises new issues, and frames understanding of neural mechanisms.
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Affiliation(s)
- Marvin M Chun
- Department of Psychology, Yale University, New Haven, Connecticut 06520, USA.
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571
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de Fockert JW, Ramchurn A, van Velzen J, Bergström Z, Bunce D. Behavioral and ERP evidence of greater distractor processing in old age. Brain Res 2009; 1282:67-73. [PMID: 19497314 DOI: 10.1016/j.brainres.2009.05.060] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 05/18/2009] [Accepted: 05/23/2009] [Indexed: 11/30/2022]
Affiliation(s)
- Jan W de Fockert
- Department of Psychology, Goldsmiths, University of London, New Cross, London SE14 6NW, UK.
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572
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Machado L, Devine A, Wyatt N. Distractibility with advancing age and Parkinson's disease. Neuropsychologia 2009; 47:1756-64. [PMID: 19397871 DOI: 10.1016/j.neuropsychologia.2009.02.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 02/05/2009] [Accepted: 02/08/2009] [Indexed: 11/16/2022]
Affiliation(s)
- Liana Machado
- Department of Psychology and Brain Health and Repair Research Centre, University of Otago, New Zealand.
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573
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Speech recognition in younger and older adults: a dependency on low-level auditory cortex. J Neurosci 2009; 29:6078-87. [PMID: 19439585 DOI: 10.1523/jneurosci.0412-09.2009] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A common complaint of older adults is difficulty understanding speech, especially in challenging listening environments. In addition to well known declines in the peripheral auditory system that reduce audibility, age-related changes in central auditory and attention-related systems are hypothesized to have additive negative effects on speech recognition. We examined the extent to which functional and structural differences in speech- and attention-related cortex predicted differences in word recognition between 18 younger adults (19-39 years) and 18 older adults (61-79 years). Subjects performed a word recognition task in an MRI scanner where the intelligibility of words was parametrically varied. Older adults exhibited significantly poorer word recognition in a challenging listening condition compared with younger adults. An anteromedial Heschl's gyrus/superior temporal gyrus (HG/STG) region, engaged by the word recognition task, exhibited age group differences in gray matter volume and predicted word recognition in younger and older adults. Age group differences in anterior cingulate (ACC) activation were also observed. The association between HG gray matter volume, word recognition, and ACC activation was present after controlling for hearing loss. In younger and older adults, causal path modeling analyses demonstrated that individual variation in left HG/STG morphology affected word recognition performance, which was reflected by error monitoring activity in the dorsal ACC. These results have clinical implications for rehabilitation and suggest that some of the perceptual difficulties experienced by older adults are due to structural changes in HG/STG. More broadly, the results suggest the possibility that aging may exaggerate developmental limitations on the ability to recognize speech.
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574
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Riis JL, Chong H, McGinnnis S, Tarbi E, Sun X, Holcomb PJ, Rentz DM, Daffner KR. Age-related changes in early novelty processing as measured by ERPs. Biol Psychol 2009; 82:33-44. [PMID: 19463888 DOI: 10.1016/j.biopsycho.2009.05.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 05/05/2009] [Accepted: 05/08/2009] [Indexed: 10/20/2022]
Abstract
This study investigated age-related changes in the early processing of novel visual stimuli using ERPs. Well-matched old (n=30), middle-aged (n=30), and young (n=32) subjects were presented standard, target/rare, and perceptually novel visual stimuli under Attend and Ignore conditions. Our results suggest that the anterior P2 component indexes the motivational salience of a stimulus as determined by either task relevance or novelty. Its enhancement by focused attention does not decrease with age. Its responsiveness to novel stimuli is particularly striking in older adults. The age-related increase in the anterior P2 to novel visual stimuli does not appear to be due to impaired inhibitory control associated with aging. Rather, the enhanced anterior P2 to novel stimuli in older adults may be linked to age-related changes in the process of matching unusual visual stimuli to stored representations, which is indexed by the temporally overlapping anterior N2 component whose amplitude substantially decreases with age.
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Affiliation(s)
- Jenna L Riis
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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575
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Dugan LL, Ali SS, Shekhtman G, Roberts AJ, Lucero J, Quick KL, Behrens MM. IL-6 mediated degeneration of forebrain GABAergic interneurons and cognitive impairment in aged mice through activation of neuronal NADPH oxidase. PLoS One 2009; 4:e5518. [PMID: 19436757 PMCID: PMC2678193 DOI: 10.1371/journal.pone.0005518] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 04/17/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Multiple studies have shown that plasma levels of the pro-inflammatory cytokine interleukin-6 (IL-6) are elevated in patients with important and prevalent adverse health conditions, including atherosclerosis, diabetes, obesity, obstructive sleep apnea, hypertension, and frailty. Higher plasma levels of IL-6, in turn, increase the risk of many conditions associated with aging including age-related cognitive decline. However, the mechanisms underlying this association between IL-6 and cognitive vulnerability remain unclear. METHODS AND FINDINGS We investigated the role of IL-6 in brain aging in young (4 mo) and aged (24 mo) wild-type C57BL6 and genetically-matched IL-6(-/-) mice, and determined that IL-6 was necessary and sufficient for increased neuronal expression of the superoxide-producing immune enzyme, NADPH-oxidase, and this was mediated by non-canonical NFkappaB signaling. Furthermore, superoxide production by NADPH-oxidase was directly responsible for age-related loss of parvalbumin (PV)-expressing GABAergic interneurons, neurons essential for normal information processing, encoding, and retrieval in hippocampus and cortex. Targeted deletion of IL-6 or elimination of superoxide by chronic treatment with a superoxide-dismutase mimetic prevented age-related loss of PV-interneurons and reversed age-related cognitive deficits on three standard tests of spatial learning and recall. CONCLUSIONS Present results indicate that IL-6 mediates age-related loss of critical PV-expressing GABAergic interneurons through increased neuronal NADPH-oxidase-derived superoxide production, and that rescue of these interneurons preserves cognitive performance in aging mice, suggesting that elevated peripheral IL-6 levels may be directly and mechanistically linked to long-lasting cognitive deficits in even normal older individuals. Further, because PV-interneurons are also selectively affected by commonly used anesthetic agents and drugs, our findings imply that IL-6 levels may predict adverse CNS effects in older patients exposed to these compounds through specific derangements in inhibitory interneurons, and that therapies directed at lowering IL-6 may have cognitive benefits clinically.
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Affiliation(s)
- Laura L Dugan
- Division of Geriatric Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA.
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576
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Campbell KL, Al-Aidroos N, Pratt J, Hasher L. Repelling the young and attracting the old: examining age-related differences in saccade trajectory deviations. Psychol Aging 2009; 24:163-8. [PMID: 19290747 DOI: 10.1037/a0014106] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the present study, the authors examined age-related differences in saccade curvature as older and younger adults looked to an X target that appeared concurrently with an O distractor. They used a fixation gap procedure to introduce variance into the saccadic latencies of both groups. Consistent with earlier findings, younger adults' early onset saccades curved toward the distractor (as the distractor competed with the target for response selection), while late-onset saccades curved away from the distractor (as the distractor location became inhibited over time). In contrast, older adults' saccades gradually decreased in curvature toward the distractor, but at no point along the latency continuum did they show deviations away. These results suggest that while the local inhibitory mechanisms responsible for decreases in curvature toward distractors may be preserved with age, aging may lead to a selective decline in the frontal inhibitory mechanisms responsible for deviations away from distractors.
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Affiliation(s)
- Karen L Campbell
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada.
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577
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Rule violation errors are associated with right lateral prefrontal cortex atrophy in neurodegenerative disease. J Int Neuropsychol Soc 2009; 15:354-64. [PMID: 19402921 PMCID: PMC2748220 DOI: 10.1017/s135561770909050x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Good cognitive performance requires adherence to rules specific to the task at hand. Patients with neurological disease often make rule violation (RV) errors, but the anatomical basis for RV during cognitive testing remains debated. The present study examined the neuroanatomical correlates of RV errors made on tests of executive functioning in 166 subjects diagnosed with neurodegenerative disease or as neurologically healthy. Specifically, RV errors were voxel-wisely correlated with gray matter volume derived from high-definition magnetic resonance images using voxel-based morphometry implemented in SPM2. Latent variable analysis showed that RV errors tapped a unitary construct separate from repetition errors. This analysis was used to generate factor scores to represent what is common among RV errors across tests. The extracted RV factor scores correlated with tissue loss in the lateral middle and inferior frontal gyri and the caudate nucleus bilaterally. When a more stringent control for global cognitive functioning was applied using Mini Mental State Exam scores, only the correlations with the right lateral prefrontal cortex (PFC) remained significant. These data underscore the importance of right lateral PFC in behavioral monitoring and highlight the potential of RV error assessment for identifying patients with damage to this region.
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578
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Abstract
Our ability to focus attention on task-relevant information and ignore distractions is reflected by differential enhancement and suppression of neural activity in sensory cortex (i.e., top-down modulation). Such selective, goal-directed modulation of activity may be intimately related to memory, such that the focus of attention biases the likelihood of successfully maintaining relevant information by limiting interference from irrelevant stimuli. Despite recent studies elucidating the mechanistic overlap between attention and memory, the relationship between top-down modulation of visual processing during working memory (WM) encoding, and subsequent recognition performance has not yet been established. Here, we provide neurophysiological evidence in healthy, young adults that top-down modulation of early visual processing (< 200 ms from stimulus onset) is intimately related to subsequent WM performance, such that the likelihood of successfully remembering relevant information is associated with limiting interference from irrelevant stimuli. The consequences of a failure to ignore distractors on recognition performance was replicated for two types of feature-based memory, motion direction and color. Moreover, attention to irrelevant stimuli was reflected neurally during the WM maintenance period as an increased memory load. These results suggest that neural enhancement of relevant information is not the primary determinant of high-level performance, but rather optimal WM performance is dependent on effectively filtering irrelevant information through neural suppression to prevent overloading a limited memory capacity.
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579
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Abstract
Past research has demonstrated that performance on frontal lobe-dependent tasks is associated with dopamine system integrity and that various dopamine system deficits occur with aging. The positron emission tomography (PET) radiotracer 6-[(18)F]fluoro-l-m-tyrosine (FMT) is a substrate of the dopamine-synthesizing enzyme, aromatic amino acid decarboxylase (AADC). Studies using 6-[(18)F]fluorodopa (FDOPA) (another AADC substrate) to measure how striatal PET signal and age relate have had inconsistent outcomes. The varying results occur in part from tracer processing that renders FDOPA signal subject to aspects of postrelease metabolism, which may themselves change with aging. In contrast, FMT remains a purer measure of AADC function. We used partial volume-corrected FMT PET scans to measure age-related striatal dopamine synthesis capacity in 21 older (mean, 66.9) and 16 younger (mean, 22.8) healthy adults. We also investigated how striatal FMT signal related to a cognitive measure of frontal lobe function. Older adults showed significantly greater striatal FMT signal than younger adults. Within the older group, FMT signal in dorsal caudate (DCA) and dorsal putamen was greater with age, suggesting compensation for deficits elsewhere in the dopamine system. In younger adults, FMT signal in DCA was lower with age, likely related to ongoing developmental processes. Younger adults who performed worse on tests of frontal lobe function showed greater FMT signal in right DCA, independent of age effects. Our data suggest that higher striatal FMT signal represents nonoptimal dopamine processing. They further support a relationship between striatal dopamine processing and frontal lobe cognitive function.
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580
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Samanez-Larkin GR, D'Esposito M. Group comparisons: imaging the aging brain. Soc Cogn Affect Neurosci 2009; 3:290-7. [PMID: 18846241 DOI: 10.1093/scan/nsn029] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
With the recent growth of functional magnetic resonance imaging (fMRI), scientists across a range of disciplines are comparing neural activity between groups of interest, such as healthy controls and clinical patients, children and young adults and younger and older adults. In this edition of Tools of the Trade, we will discuss why great caution must be taken when making group comparisons in studies using fMRI. Although many methodological contributions have been made in recent years, the suggestions for overcoming common issues are too often overlooked. This review focuses primarily on neuroimaging studies of healthy aging, but many of the issues raised apply to other group designs as well.
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581
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Rajah M, Bastianetto S, Bromley-Brits K, Cools R, D’Esposito M, Grady C, Poirier J, Quirion R, Raz N, Rogaeva E, Song W, Pruessner J. Biological changes associated with healthy versus pathological aging: a symposium review. Ageing Res Rev 2009; 8:140-6. [PMID: 19274854 DOI: 10.1016/j.arr.2009.01.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Douglas Mental Health University Institute, in collaboration with the McGill Centre for Studies in Aging, organized a 2-day symposium entitled "Biological Changes Associated with Healthy Versus Pathological Aging" that was held in 13 and 14 December 2007 on the Douglas campus. The symposium involved presentations on current trends in aging and dementia research across several sub-disciplines: genetics, neurochemistry, structural and functional neuroimaging and clinical treatment and rehabilitation. The goal of this symposium was to provide a forum for knowledge-transfer between scientists and clinicians with different specializations in order to promote cross-fertilization of research ideas that would lead to future collaborative neuroscience research in aging and dementia. In this review article, we summarize the presentations made by the 13 international scientists at the symposium and highlight: (i) past research, and future research trends in neuroscience of aging and dementia and (ii) links across levels of analysis that can lead to fruitful transdisciplinary research programs that will advance knowledge about the neurobiological changes associated with healthy aging and dementia.
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582
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Cocchi L, Bosisio F, Berchtold A, Orita A, Debbané M, Wood SJ, Schenk F. Visuospatial encoding deficits and compensatory strategies in schizophrenia revealed by eye movement analysis during a working memory task. Acta Neuropsychiatr 2009; 21:75-83. [PMID: 25384566 DOI: 10.1111/j.1601-5215.2009.00369.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE To investigate scanpath abnormalities during the encoding of static stimuli in schizophrenia and their interaction with visuospatial working memory (VSWM) dysfunction. METHODS Outpatients with schizophrenia and control subjects were asked to encode a static pattern for subsequent recognition after a short delay. We measured the number of correct and incorrect choices. We also assessed the number and the distribution of fixations, the scanning time in specific regions of interest (ROIs) and the head movements during the encoding of the stimuli. The distributions of fixations and scanning time in definite ROIs during the discrimination of the correct pattern from the foils were also measured. RESULTS Patients recognised fewer correct patterns than controls. Correct trials in patients were characterised by a specific exploration of the central part of the stimulus during its presentation, whereas this feature was absent in incorrect trials. However, the scanning time and the numbers of fixations and head movements during encoding were similar in both groups and unrelated to recognition accuracy. In both groups, correct trials were associated with a selective exploration of the correct pattern amongst the six possibilities during recognition. Furthermore, patients gave more attention to incorrect patterns with a leftmost element identical to that of the correct response and also those approximating its global structure. CONCLUSION Patients showed a VSWM deficit independent of oculomotor dysfunctions and head movements during encoding. Patients' correct trials were related to specific scanning during encoding and discrimination phases. Analysis of these patterns suggests that patients try to compensate for reduced VSWM ability by using specific encoding strategies.
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Affiliation(s)
- Luca Cocchi
- 1Melbourne Neuropsychiatry Centre, University of Melbourne, c/o National Neuroscience Facility, Melbourne, Australia
| | | | - André Berchtold
- 5Institute of Applied Mathematics (IMA), University of Lausanne, Switzerland
| | - Alina Orita
- 6University Psychiatric Adult Department of Lausanne (DUPA), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Martin Debbané
- 7Service Médico-Pédagogique, University of Geneva School of Medicine, Geneva, Switzerland
| | - Stephen J Wood
- 1Melbourne Neuropsychiatry Centre, University of Melbourne, c/o National Neuroscience Facility, Melbourne, Australia
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583
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Ashley V, Swick D. Consequences of emotional stimuli: age differences on pure and mixed blocks of the emotional Stroop. Behav Brain Funct 2009; 5:14. [PMID: 19254381 PMCID: PMC2661089 DOI: 10.1186/1744-9081-5-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Accepted: 03/02/2009] [Indexed: 11/10/2022] Open
Abstract
Background Studies of aging and emotion suggest that older adults show diminished responsiveness to negative information, possibly resulting from increased emotion regulation, but the mechanisms accounting for this effect are uncertain. Methods To examine whether aging affects the allocation of attention to negative stimuli, we compared 20 younger and 20 older adults on 2 versions of the emotional Stroop task: "pure blocks," in which all words in each block were either emotional or neutral, and "mixed blocks," a pseudorandomized design in which either a negative emotional or a neutral category word was always followed by six neutral words. The emotional Stroop task typically elicits slower reaction times for naming the font color of negative emotional words compared to neutral, but no studies have examined the effects of aging on the immediate and sustained components of the emotional Stroop effect. Results Both groups showed an emotional Stroop effect on pure blocks manifest as slower RTs on the emotional, relative to the neutral, block. However, only younger adults showed persistent slowing that carried over from emotional words onto subsequent neutral words in mixed blocks. Conclusion These results suggest that the consequences of emotional stimuli may differ with age. Younger and older adults showed equivalent interference from the emotional words themselves, but older adults did not show a sustained effect of negative information.
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Affiliation(s)
- Victoria Ashley
- Research Service, Veterans Affairs Northern California Health Care System, Martinez, California, USA.
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584
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Rissman J, Gazzaley A, D'Esposito M. The effect of non-visual working memory load on top-down modulation of visual processing. Neuropsychologia 2009; 47:1637-46. [PMID: 19397858 DOI: 10.1016/j.neuropsychologia.2009.01.036] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 01/14/2009] [Accepted: 01/26/2009] [Indexed: 11/25/2022]
Abstract
While a core function of the working memory (WM) system is the active maintenance of behaviorally relevant sensory representations, it is also critical that distracting stimuli are appropriately ignored. We used functional magnetic resonance imaging to examine the role of domain-general WM resources in the top-down attentional modulation of task-relevant and irrelevant visual representations. In our dual-task paradigm, each trial began with the auditory presentation of six random (high load) or sequentially ordered (low load) digits. Next, two relevant visual stimuli (e.g., faces), presented amongst two temporally interspersed visual distractors (e.g., scenes), were to be encoded and maintained across a 7-s delay interval, after which memory for the relevant images and digits was probed. When taxed by high load digit maintenance, participants exhibited impaired performance on the visual WM task and a selective failure to attenuate the neural processing of task-irrelevant scene stimuli. The over-processing of distractor scenes under high load was indexed by elevated encoding activity in a scene-selective region-of-interest relative to low load and passive viewing control conditions, as well as by improved long-term recognition memory for these items. In contrast, the load manipulation did not affect participants' ability to upregulate activity in this region when scenes were task-relevant. These results highlight the critical role of domain-general WM resources in the goal-directed regulation of distractor processing. Moreover, the consequences of increased WM load in young adults closely resemble the effects of cognitive aging on distractor filtering [Gazzaley, A., Cooney, J. W., Rissman, J., & D'Esposito, M. (2005). Top-down suppression deficit underlies working memory impairment in normal aging. Nature Neuroscience 8, 1298-1300], suggesting the possibility of a common underlying mechanism.
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Affiliation(s)
- Jesse Rissman
- Henry H. Wheeler Jr. Brain Imaging Center, University of California, Berkeley, 94720, USA.
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585
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Cocchi L, Debbané M, Vianin P, Bircher R, Roulin S, Conus P, Sarrasin-Bruchez P, Bovet P, Volken H, Wood SJ, Schenk F. Encoding dysfunctions in a dynamic-static paradigm for visuospatial working memory in first-episode psychosis patients: a 2-year follow-up study. Early Interv Psychiatry 2009; 3:44-51. [PMID: 21352174 DOI: 10.1111/j.1751-7893.2008.00101.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIM To investigate static and dynamic visuospatial working memory (VSWM) processes in first-episode psychosis (FEP) patients and explore the validity of such measures as specific trait markers of schizophrenia. METHODS Twenty FEP patients and 20 age-, sex-, laterality- and education-matched controls carried out a dynamic and static VSWM paradigm. At 2-year follow up 13 patients met Diagnostic and Statistical Manual (of Mental Health Disorders)--Fourth Edition (DSM-IV) criteria for schizophrenia, 1 for bipolar disorder, 1 for brief psychotic episode and 5 for schizotypal personality disorder. RESULTS Compared with controls, the 20 FEP patients showed severe impairment in the dynamic VSWM condition but much less impairment in the static condition. No specific bias in stimulus selection was detected in the two tasks. Two-year follow-up evaluations suggested poorer baseline scores on the dynamic task clearly differentiated the 13 FEP patients who developed schizophrenia from the seven who did not. CONCLUSIONS Results suggest deficits in VSWM in FEP patients. Specific exploratory analyses further suggest that deficit in monitoring-manipulation VSWM processes, especially involved in our dynamic VSWM task, can be a reliable marker of schizophrenia.
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Affiliation(s)
- Luca Cocchi
- Institute of Sport Science and Physical Education, Department of Physiology, Lausanne University, Lausanne, Switzerland.
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586
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Abstract
Older adults have reduced memory, primarily for recall, but also for recognition (Craik and McDowd, 1987), particularly for unfamiliar faces (Bartlett et al., 1989). Behavioral studies have shown that age-related memory declines are due in part to distraction from impaired inhibition of task-irrelevant input during encoding (Healey et al., 2008). Functional magnetic resonance imaging (fMRI) has been used to uncover the sources of memory deficits associated with aging. To date, this work has focused on successful encoding, while the neural correlates of unsuccessful encoding are unknown. Here, we provide novel evidence of a neural mechanism underlying memory failures exclusively affecting older adults. Whereas both younger and older adults showed reduced activation of brain regions important for encoding (e.g., hippocampus) during unsuccessful encoding, only older adults showed increased activity in brain regions mediating distraction (e.g., auditory cortex) and in left prefrontal cortex. Further, these regions were functionally connected with medial parietal areas, previously identified as default mode regions (Raichle and Snyder, 2007), which may reflect environmental monitoring. Our results suggest that increased distraction from task-irrelevant input (auditory in this case), associated with the unfamiliar and noisy fMRI environment, may increase environmental monitoring. This in turn could hinder suppression of default mode processing, resulting in memory failures in older adults. These findings provide novel evidence of a brain mechanism underlying the behavioral evidence that impaired inhibition of extraneous input during encoding leads to memory failure in older adults and may have implications for the ubiquitous use of fMRI for investigating neurocognitive aging.
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587
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Age-related differences in processing irrelevant information: Evidence from event-related potentials. Neuropsychologia 2009; 47:577-86. [DOI: 10.1016/j.neuropsychologia.2008.10.018] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 10/03/2008] [Accepted: 10/15/2008] [Indexed: 11/23/2022]
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588
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Age-related top-down suppression deficit in the early stages of cortical visual memory processing. Proc Natl Acad Sci U S A 2008; 105:13122-6. [PMID: 18765818 DOI: 10.1073/pnas.0806074105] [Citation(s) in RCA: 313] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this study, electroencephalography (EEG) was used to examine the relationship between two leading hypotheses of cognitive aging, the inhibitory deficit and the processing speed hypothesis. We show that older adults exhibit a selective deficit in suppressing task-irrelevant information during visual working memory encoding, but only in the early stages of visual processing. Thus, the employment of suppressive mechanisms are not abolished with aging but rather delayed in time, revealing a decline in processing speed that is selective for the inhibition of irrelevant information. EEG spectral analysis of signals from frontal regions suggests that this results from excessive attention to distracting information early in the time course of viewing irrelevant stimuli. Subdividing the older population based on working memory performance revealed that impaired suppression of distracting information early in the visual processing stream is associated with poorer memory of task-relevant information. Thus, these data reconcile two cognitive aging hypotheses by revealing that an interaction of deficits in inhibition and processing speed contributes to age-related cognitive impairment.
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589
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Sambataro F, Murty VP, Callicott JH, Tan HY, Das S, Weinberger DR, Mattay VS. Age-related alterations in default mode network: impact on working memory performance. Neurobiol Aging 2008; 31:839-52. [PMID: 18674847 DOI: 10.1016/j.neurobiolaging.2008.05.022] [Citation(s) in RCA: 371] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 05/21/2008] [Accepted: 05/25/2008] [Indexed: 11/25/2022]
Abstract
The default mode network (DMN) is a set of functionally connected brain regions which shows deactivation (task-induced deactivation, TID) during a cognitive task. Evidence shows an age-related decline in task-load-related modulation of the activity within the DMN during cognitive tasks. However, the effect of age on the functional coupling within the DMN and their relation to cognitive performance has hitherto been unexplored. Using functional magnetic resonance imaging, we investigated functional connectivity within the DMN in older and younger subjects during a working memory task with increasing task load. Older adults showed decreased connectivity and ability to suppress low frequency oscillations of the DMN. Additionally, the strength of the functional coupling of posterior cingulate (pCC) with medial prefrontal cortex (PFC) correlated positively with performance and was lower in older adults. pCC was also negatively coupled with task-related regions, namely the dorsolateral PFC and cingulate regions. Our results show that in addition to changes in canonical task-related brain regions, normal aging is also associated with alterations in the activity and connectivity of brain regions within the DMN. These changes may be a reflection of a deficit in cognitive control associated with advancing age that results in deficient resource allocation to the task at hand.
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Affiliation(s)
- Fabio Sambataro
- Genes, Cognition, and Psychosis Program, Clinical Brain Disorders Branch, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
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590
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Solbakk AK, Fuhrmann Alpert G, Furst AJ, Hale LA, Oga T, Chetty S, Pickard N, Knight RT. Altered prefrontal function with aging: insights into age-associated performance decline. Brain Res 2008; 1232:30-47. [PMID: 18691562 DOI: 10.1016/j.brainres.2008.07.060] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 07/06/2008] [Accepted: 07/07/2008] [Indexed: 10/21/2022]
Abstract
We examined the effects of aging on visuo-spatial attention. Participants performed a bi-field visual selective attention task consisting of infrequent target and task-irrelevant novel stimuli randomly embedded among repeated standards in either attended or unattended visual fields. Blood oxygenation level dependent (BOLD) responses to the different classes of stimuli were measured using functional magnetic resonance imaging. The older group had slower reaction times to targets, and committed more false alarms but had comparable detection accuracy to young controls. Attended target and novel stimuli activated comparable widely distributed attention networks, including anterior and posterior association cortex, in both groups. The older group had reduced spatial extent of activation in several regions, including prefrontal, basal ganglia, and visual processing areas. In particular, the anterior cingulate and superior frontal gyrus showed more restricted activation in older compared with young adults across all attentional conditions and stimulus categories. The spatial extent of activations correlated with task performance in both age groups, but the regional pattern of association between hemodynamic responses and behavior differed between the groups. Whereas the young subjects relied on posterior regions, the older subjects engaged frontal areas. The results indicate that aging alters the functioning of neural networks subserving visual attention, and that these changes are related to cognitive performance.
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Affiliation(s)
- Anne-Kristin Solbakk
- Department of Psychology and the Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.
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591
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SanMiguel I, Corral MJ, Escera C. When Loading Working Memory Reduces Distraction: Behavioral and Electrophysiological Evidence from an Auditory-Visual Distraction Paradigm. J Cogn Neurosci 2008; 20:1131-45. [DOI: 10.1162/jocn.2008.20078] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
The sensitivity of involuntary attention to top-down modulation was tested using an auditory-visual distraction task and a working memory (WM) load manipulation in subjects performing a simple visual classification task while ignoring contingent auditory stimulation. The sounds were repetitive standard tones (80%) and environmental novel sounds (20%). Distraction caused by the novel sounds was compared across a 1-back WM condition and a no-memory control condition, both involving the comparison of two digits. Event-related brain potentials (ERPs) to the sounds were recorded, and the N1/MMN (mismatch negativity), novelty-P3, and RON components were identified in the novel minus standard difference waveforms. Distraction was reduced in the WM condition, both behaviorally and as indexed by an attenuation of the late phase of the novelty-P3. The transient/change detection mechanism indexed by MMN was not affected by the WM manipulation. Sustained, slow frontal and parietal waveforms related to WM processes were found on the standard ERPs. The present results indicate that distraction caused by irrelevant novel sounds is reduced when a WM component is involved in the task, and that this modulation by WM load takes place at a late stage of the orienting response, all in all confirming that involuntary attention is under the control of top-down mechanisms. Moreover, as these results contradict predictions of the load theory of selective attention and cognitive control, it is suggested that the WM load effects on distraction depend on the nature of the distractor-target relationships.
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592
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Abstract
The number of reports on the cognitive neuroscience of aging has increased in recent years, and most of these studies have found many similarities in the patterns of activity in young and old adults, indicating that basic neural mechanisms are maintained into older age. Despite these overall similarities, older adults often have less activity in some regions, such as medial temporal areas during memory processing and visual regions across a variety of cognitive domains. It seems clear that age reductions in cognitive function can be tied, at least in part, to these reductions in brain activity. On the other hand, older adults typically also overrecruit some brain areas, mainly the ventral or dorsal prefrontal cortex during memory tasks, as well as both the frontal and parietal regions during tasks engaging cognitive control processes, such as attention. Sometimes this overrecruitment appears to be in response to altered function in other brain regions and is often seen in those older adults who perform better on the task at hand. These findings have provided rather convincing support for the idea that overrecruitment can be compensatory in the elderly. Nevertheless, not all age increases can be interpreted as compensatory, and some are more indicative of neural inefficiency. The challenge facing future research will be to understand the task conditions that promote compensation in older adults, the role of the various brain areas in aiding cognitive function, and how these compensatory mechanisms can be elicited to enhance quality of life in the elderly.
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Affiliation(s)
- Cheryl L Grady
- Rotman Research Institute at Baycrest, 3560 Bathurst St., Toronto, Ontario M6A 2E1, Canada.
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593
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Reuter-Lorenz PA, Cappell KA. Neurocognitive Aging and the Compensation Hypothesis. CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 2008. [DOI: 10.1111/j.1467-8721.2008.00570.x] [Citation(s) in RCA: 949] [Impact Index Per Article: 59.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The most unexpected and intriguing result from functional brain imaging studies of cognitive aging is evidence for age-related overactivation: greater activation in older adults than in younger adults, even when performance is age-equivalent. Here we examine the hypothesis that age-related overactivation is compensatory and discuss the compensation-related utilization of neural circuits hypothesis (CRUNCH). We review evidence that favors a compensatory account, discuss questions about strategy differences, and consider the functions that may be served by overactive brain areas. Future research directed at neurocognitively informed training interventions may augment the potential for plasticity that persists into the later years of the human lifespan.
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594
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595
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Ikier S, Yang L, Hasher L. Implicit Proactive Interference, Age, and Automatic Versus Controlled Retrieval Strategies. Psychol Sci 2008; 19:456-61. [DOI: 10.1111/j.1467-9280.2008.02109.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We assessed the extent to which implicit proactive interference results from automatic versus controlled retrieval among younger and older adults. During a study phase, targets (e.g., “ALLERGY”) either were or were not preceded by nontarget competitors (e.g., “ANALOGY”). After a filled interval, the participants were asked to complete word fragments, some of which cued studied words (e.g., “A_L__GY”). Retrieval strategies were identified by the difference in response speed between a phase containing fragments that cued only new words and a phase that included a mix of fragments cuing old and new words. Previous results were replicated: Proactive interference was found in implicit memory, and the negative effects were greater for older than for younger adults. Novel findings demonstrate two retrieval processes that contribute to interference: an automatic one that is age invariant and a controlled process that can reduce the magnitude of the automatic interference effects. The controlled process, however, is used effectively only by younger adults. This pattern of findings potentially explains age differences in susceptibility to proactive interference.
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Affiliation(s)
| | | | - Lynn Hasher
- University of Toronto
- The Rotman Research Institute of Baycrest Centre
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596
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Davis SW, Dennis NA, Daselaar SM, Fleck MS, Cabeza R. Que PASA? The posterior-anterior shift in aging. Cereb Cortex 2008; 18:1201-9. [PMID: 17925295 PMCID: PMC2760260 DOI: 10.1093/cercor/bhm155] [Citation(s) in RCA: 847] [Impact Index Per Article: 52.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A consistent finding from functional neuroimaging studies of cognitive aging is an age-related reduction in occipital activity coupled with increased frontal activity. This posterior-anterior shift in aging (PASA) has been typically attributed to functional compensation. The present functional magnetic resonance imaging sought to 1) confirm that PASA reflects the effects of aging rather than differences in task difficulty; 2) test the compensation hypothesis; and 3) investigate whether PASA generalizes to deactivations. Young and older participants were scanned during episodic retrieval and visual perceptual tasks, and age-related changes in brain activity common to both tasks were identified. The study yielded 3 main findings. First, inconsistent with a difficulty account, the PASA pattern was found across task and confidence levels when matching performance among groups. Second, supporting the compensatory hypothesis, age-related increases in frontal activity were positively correlated with performance and negatively correlated with the age-related occipital decreases. Age-related increases and correlations with parietal activity were also found. Finally, supporting the generalizability of the PASA pattern to deactivations, aging reduced deactivations in posterior midline cortex but increased deactivations in medial frontal cortex. Taken together, these findings demonstrate the validity, function, and generalizability of PASA, as well as its importance for the cognitive neuroscience of aging.
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Affiliation(s)
- Simon W. Davis
- Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA
| | - Nancy A. Dennis
- Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA
| | - Sander M. Daselaar
- Faculty of Science, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Mathias S. Fleck
- Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA
| | - Roberto Cabeza
- Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA
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597
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Wild-Wall N, Falkenstein M, Hohnsbein J. Flanker interference in young and older participants as reflected in event-related potentials. Brain Res 2008; 1211:72-84. [PMID: 18433737 DOI: 10.1016/j.brainres.2008.03.025] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 12/21/2007] [Accepted: 03/15/2008] [Indexed: 10/22/2022]
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598
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Raye CL, Mitchell KJ, Reeder JA, Greene EJ, Johnson MK. Refreshing One of Several Active Representations: Behavioral and Functional Magnetic Resonance Imaging Differences between Young and Older Adults. J Cogn Neurosci 2008; 20:852-62. [DOI: 10.1162/jocn.2008.20508] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractWe explored age-related differences in executive function during selection of a target from among active representations. Refreshing (thinking briefly of a just-activated representation) is an executive process that foregrounds a target relative to other active representations. In a behavioral study, participants saw one or three words, then saw a cue to refresh one of the words, saw one word again and read it, or read a new word. Increasing the number of active representations increased response times (RTs) only in the refresh condition for young adults but increased RTs equally in all conditions for older adults, suggesting that they experienced interference from activated irrelevant information during perception and reflection. Consistent with this interpretation, in a functional magnetic resonance imaging study, young adults showed two areas of the left dorsolateral frontal cortex and a medial area of frontal cortex, including anterior cingulate, that were relatively more sensitive to number of active representations during refresh than read trials; for older adults these areas were equally sensitive to number of active items for refresh and read trials. Young and older adults showed activity associated with refreshing on trials requiring selection in left mid-ventral frontal cortex (an area associated with selection from active representations); older adults also showed activity in left anterior ventral frontal cortex (an area associated with controlled semantic activation). Our results support the hypothesis of an age-related decrease in ability to gate out activated but currently irrelevant information, and are consistent with a dissociation of function between eft mid-ventral and left anterior ventral frontal cortex.
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599
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Vaughan BS, Wetzel MW, Kratochvil CJ. Beyond the 'typical' patient: treating attention-deficit/hyperactivity disorder in preschoolers and adults. Int Rev Psychiatry 2008; 20:143-9. [PMID: 18386204 DOI: 10.1080/09540260801887751] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Attention-deficit/hyperactivity disorder (ADHD), typically affects school-aged children, but can present during the preschool years and persist into adulthood. Accurate diagnosis for preschoolers and adults requires adaptation of the current diagnostic criteria to account for differences in symptomatology across the age span. The differential diagnosis of ADHD and the pattern of psychiatric comorbidity vary with each age group and complicate diagnosis and management. To maximize outcomes clinicians must be able to accurately identify ADHD across the lifespan, and develop comprehensive, collaborative treatment plans. The Preschool ADHD Treatment Study (PATS) demonstrated the potential utility of methylphenidate for treating ADHD in preschoolers, and trials of psychostimulants and atomoxetine have shown some benefits for adults. Behavioural interventions likely have an adjunctive role in ADHD treatment for both groups. More research, however, is needed to determine the safest and most effective pharmacotherapies and psychosocial interventions for these non-typical patients.
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Affiliation(s)
- Brigette S Vaughan
- Department of Psychiatry, University of Nebraska Medical Center, Omaha, NE 68198-5581, USA
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600
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Andrews-Hanna JR, Snyder AZ, Vincent JL, Lustig C, Head D, Raichle ME, Buckner RL. Disruption of large-scale brain systems in advanced aging. Neuron 2008; 56:924-35. [PMID: 18054866 DOI: 10.1016/j.neuron.2007.10.038] [Citation(s) in RCA: 1169] [Impact Index Per Article: 73.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 09/01/2007] [Accepted: 10/29/2007] [Indexed: 01/17/2023]
Abstract
Cognitive decline is commonly observed in advanced aging even in the absence of disease. Here we explore the possibility that normal aging is accompanied by disruptive alterations in the coordination of large-scale brain systems that support high-level cognition. In 93 adults aged 18 to 93, we demonstrate that aging is characterized by marked reductions in normally present functional correlations within two higher-order brain systems. Anterior to posterior components within the default network were most severely disrupted with age. Furthermore, correlation reductions were severe in older adults free from Alzheimer's disease (AD) pathology as determined by amyloid imaging, suggesting that functional disruptions were not the result of AD. Instead, reduced correlations were associated with disruptions in white matter integrity and poor cognitive performance across a range of domains. These results suggest that cognitive decline in normal aging arises from functional disruption in the coordination of large-scale brain systems that support cognition.
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Affiliation(s)
- Jessica R Andrews-Hanna
- Department of Psychology, Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
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