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Matynia A, Recio BS, Myers Z, Parikh S, Goit RK, Brecha NC, Pérez de Sevilla Müller L. Preservation of Intrinsically Photosensitive Retinal Ganglion Cells (ipRGCs) in Late Adult Mice: Implications as a Potential Biomarker for Early Onset Ocular Degenerative Diseases. Invest Ophthalmol Vis Sci 2024; 65:28. [PMID: 38224335 PMCID: PMC10793389 DOI: 10.1167/iovs.65.1.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 11/27/2023] [Indexed: 01/16/2024] Open
Abstract
Purpose Intrinsically photosensitive retinal ganglion cells (ipRGCs) play a crucial role in non-image-forming visual functions. Given their significant loss observed in various ocular degenerative diseases at early stages, this study aimed to assess changes in both the morphology and associated behavioral functions of ipRGCs in mice between 6 (mature) and 12 (late adult) months old. The findings contribute to understanding the preservation of ipRGCs in late adults and their potential as a biomarker for early ocular degenerative diseases. Methods Female and male C57BL/6J mice were used to assess the behavioral consequences of aging to mature and old adults, including pupillary light reflex, light aversion, visual acuity, and contrast sensitivity. Immunohistochemistry on retinal wholemounts from these mice was then conducted to evaluate ipRGC dendritic morphology in the ganglion cell layer (GCL) and inner nuclear layer (INL). Results Morphological analysis showed that ipRGC dendritic field complexity was remarkably stable through 12 months old of age. Similarly, the pupillary light reflex, visual acuity, and contrast sensitivity were stable in mature and old adults. Although alterations were observed in ipRGC-independent light aversion distinct from the pupillary light reflex, aged wild-type mice continuously showed enhanced light aversion with dilation. No effect of sex was observed in any tests. Conclusions The preservation of both ipRGC morphology and function highlights the potential of ipRGC-mediated function as a valuable biomarker for ocular diseases characterized by early ipRGC loss. The consistent stability of ipRGCs in mature and old adult mice suggests that detected changes in ipRGC-mediated functions could serve as early indicators or diagnostic tools for early-onset conditions such as Alzheimer's disease, Parkinson's disease, and diabetes, where ipRGC loss has been documented.
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Affiliation(s)
- Anna Matynia
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, California, United States
| | - Brandy S. Recio
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
| | - Zachary Myers
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
| | - Sachin Parikh
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, California, United States
| | - Rajesh Kumar Goit
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, California, United States
| | - Nicholas C. Brecha
- Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, California, United States
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
| | - Luis Pérez de Sevilla Müller
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States
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Dietze N, Recker L, Poth CH. Warning signals only support the first action in a sequence. Cogn Res Princ Implic 2023; 8:29. [PMID: 37171646 PMCID: PMC10182231 DOI: 10.1186/s41235-023-00484-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/30/2023] [Indexed: 05/13/2023] Open
Abstract
Acting upon target stimuli from the environment becomes faster when the targets are preceded by a warning (alerting) cue. Accordingly, alerting is often used to support action in safety-critical contexts (e.g., honking to alert others of a traffic situation). Crucially, however, the benefits of alerting for action have been established using laboratory tasks assessing only simple choice reactions. Real-world actions are considerably more complex and mainly consist of sensorimotor sequences of several sub-actions. Therefore, it is still unknown if the benefits of alerting for action transfer from simple choice reactions to such sensorimotor sequences. Here, we investigated how alerting affected performance in a sequential action task derived from the Trail-Making-Test, a well-established neuropsychological test of cognitive action control (Experiment 1). In addition to this task, participants performed a classic alerting paradigm including a simple choice reaction task (Experiment 2). Results showed that alerting sped up responding in both tasks, but in the sequential action task, this benefit was restricted to the first action of a sequence. This was the case, even when multiple actions were performed within a short time (Experiment 3), ruling out that the restriction of alerting to the first action was due to its short-lived nature. Taken together, these findings reveal the existence of an interface between phasic alertness and action control that supports the next action.
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Affiliation(s)
- Niklas Dietze
- Department of Psychology, Neuro-Cognitive Psychology and Center for Cognitive Interaction Technology, Bielefeld University, P.O. box 10 01 31, 33501, Bielefeld, Germany.
| | - Lukas Recker
- Department of Psychology, Neuro-Cognitive Psychology and Center for Cognitive Interaction Technology, Bielefeld University, P.O. box 10 01 31, 33501, Bielefeld, Germany
| | - Christian H Poth
- Department of Psychology, Neuro-Cognitive Psychology and Center for Cognitive Interaction Technology, Bielefeld University, P.O. box 10 01 31, 33501, Bielefeld, Germany
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3
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Spatial inhibition of return is impaired in mild cognitive impairment and mild Alzheimer's disease. PLoS One 2021; 16:e0252958. [PMID: 34125847 PMCID: PMC8202934 DOI: 10.1371/journal.pone.0252958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 05/25/2021] [Indexed: 11/26/2022] Open
Abstract
Spatial inhibition of return (IOR) refers to the phenomenon by which individuals are slower to respond to stimuli appearing at a previously cued location compared to un-cued locations. Here with a group of older adults (n = 56, 58–80 (67.9±5.2) year old, 31 females, 18.7±3.6 years of education), we provide evidence supporting the notion that spatial IOR is mildly impaired in individuals with mild cognitive impairment (MCI) or mild Alzheimer’s disease (AD), and the impairment is detectable using a double cue paradigm. Furthermore, reduced spatial IOR in high-risk healthy older individuals is associated with reduced memory and other neurocognitive task performance, suggesting that the double cue spatial IOR paradigm may be useful in detecting MCI and early AD.
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Haupt M, Jödecke S, Srowig A, Napiórkowski N, Preul C, Witte OW, Finke K. Phasic alerting increases visual processing speed in amnestic mild cognitive impairment. Neurobiol Aging 2021; 102:23-31. [PMID: 33765429 DOI: 10.1016/j.neurobiolaging.2021.01.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 01/12/2021] [Accepted: 01/28/2021] [Indexed: 11/25/2022]
Abstract
External warning cues temporarily increase the brain's sensitivity for upcoming events, helping individuals to flexibly adapt their reactions to the requirements of complex visual environments. Previous studies reported that younger and cognitively normal older adults profit from phasic alerting cues. Such an intact phasic alerting mechanism could be even more relevant in individuals with Alzheimer's disease who are characterized by reduced processing capacities. The present study employed a theory of visual attention based verbal whole report paradigm with auditory cues in order to investigate phasic alerting effects in amnestic mild cognitive impairment (aMCI). Patients with aMCI were also compared to a previously reported sample of cognitively normal older adults. In patients with aMCI, visual processing speed was higher in the cue compared to the no-cue condition. Further, visual processing speed was reduced in patients with aMCI compared to cognitively normal older adults. Taken together, the results suggest that the processing system of patients with aMCI exhibits general declines but can still integrate auditory warning signals on a perceptual level.
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Affiliation(s)
- Marleen Haupt
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany; General and Experimental Psychology, Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany; Graduate School of Systemic Neurosciences (GSN), Ludwig-Maximilians-Universität München, Munich, Germany.
| | - Steffen Jödecke
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany
| | - Annie Srowig
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany
| | - Natan Napiórkowski
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany
| | - Christoph Preul
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany
| | - Otto W Witte
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany
| | - Kathrin Finke
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany; General and Experimental Psychology, Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany
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Almubark I, Chang LC, Shattuck KF, Nguyen T, Turner RS, Jiang X. A 5-min Cognitive Task With Deep Learning Accurately Detects Early Alzheimer's Disease. Front Aging Neurosci 2020; 12:603179. [PMID: 33343337 PMCID: PMC7744695 DOI: 10.3389/fnagi.2020.603179] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 11/13/2020] [Indexed: 12/15/2022] Open
Abstract
Introduction: The goal of this study was to investigate and compare the classification performance of machine learning with behavioral data from standard neuropsychological tests, a cognitive task, or both. Methods: A neuropsychological battery and a simple 5-min cognitive task were administered to eight individuals with mild cognitive impairment (MCI), eight individuals with mild Alzheimer's disease (AD), and 41 demographically match controls (CN). A fully connected multilayer perceptron (MLP) network and four supervised traditional machine learning algorithms were used. Results: Traditional machine learning algorithms achieved similar classification performances with neuropsychological or cognitive data. MLP outperformed traditional algorithms with the cognitive data (either alone or together with neuropsychological data), but not neuropsychological data. In particularly, MLP with a combination of summarized scores from neuropsychological tests and the cognitive task achieved ~90% sensitivity and ~90% specificity. Applying the models to an independent dataset, in which the participants were demographically different from the ones in the main dataset, a high specificity was maintained (100%), but the sensitivity was dropped to 66.67%. Discussion: Deep learning with data from specific cognitive task(s) holds promise for assisting in the early diagnosis of Alzheimer's disease, but future work with a large and diverse sample is necessary to validate and to improve this approach.
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Affiliation(s)
- Ibrahim Almubark
- Department of Electrical Engineering and Computer Science, Catholic University of America, Washington, DC, United States
| | - Lin-Ching Chang
- Department of Electrical Engineering and Computer Science, Catholic University of America, Washington, DC, United States
| | - Kyle F Shattuck
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States
| | - Thanh Nguyen
- Department of Electrical Engineering and Computer Science, Catholic University of America, Washington, DC, United States
| | - Raymond Scott Turner
- Department of Neurology, Georgetown University Medical Center, Washington, DC, United States
| | - Xiong Jiang
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States
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Lacking Pace but Not Precision: Age-Related Information Processing Changes in Response to a Dynamic Attentional Control Task. Brain Sci 2020; 10:brainsci10060390. [PMID: 32575518 PMCID: PMC7349744 DOI: 10.3390/brainsci10060390] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/01/2020] [Accepted: 06/14/2020] [Indexed: 11/17/2022] Open
Abstract
Age-related decline in information processing can have a substantial impact on activities such as driving. However, the assessment of these changes is often carried out using cognitive tasks that do not adequately represent the dynamic process of updating environmental stimuli. Equally, traditional tests are often static in their approach to task complexity, and do not assess difficulty within the bounds of an individual’s capability. To address these limitations, we used a more ecologically valid measure, the Swansea Test of Attentional Control (STAC), in which a threshold for information processing speed is established at a given level of accuracy. We aimed to delineate how older, compared to younger, adults varied in their performance of the task, while also assessing relationships between the task outcome and gender, general cognition (MoCA), perceived memory function (MFQ), cognitive reserve (NART), and aspects of mood (PHQ-9, GAD-7). The results indicate that older adults were significantly slower than younger adults but no less precise, irrespective of gender. Age was negatively correlated with the speed of task performance. Our measure of general cognition was positively correlated with the task speed threshold but not with age per se. Perceived memory function, cognitive reserve, and mood were not related to task performance. The findings indicate that while attentional control is less efficient in older adulthood, age alone is not a defining factor in relation to accuracy. In a real-life context, general cognitive function, in conjunction with dynamic measures such as STAC, may represent a far more effective strategy for assessing the complex executive functions underlying driving ability.
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Chen Y, He H, Xu P, Wang J, Qiu Y, Feng W, Luo Y, Hu L, Guan Q. The Weakened Relationship Between Prestimulus Alpha Oscillations and Response Time in Older Adults With Mild Cognitive Impairment. Front Hum Neurosci 2020; 14:48. [PMID: 32226365 PMCID: PMC7080651 DOI: 10.3389/fnhum.2020.00048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 02/03/2020] [Indexed: 11/24/2022] Open
Abstract
Background: Prestimulus alpha oscillations associated with preparatory attention have an impact on response time (RT). However, little is known about whether there is a deficit in the relationship between prestimulus alpha oscillations and RT in older adults with mild cognitive impairment (MCI). Method: We collected electroencephalography (EEG) data from 28 older adults with MCI and 28 demographically matched healthy controls (HCs) when they were performing an Eriksen flanker task. For each participant, single-trial prestimulus alpha power was calculated for combinations of congruency (congruent vs. incongruent) and response speed (fast vs. slow). Result: Statistical analysis indicated that prestimulus alpha power was significantly lower for fast trials than slow trials in HCs but not in older adults with MCI. The Fisher’s z scores of the within-subject correlation coefficients between single-trial prestimulus alpha power and RT were significantly larger in HCs than in older adults with MCI. In addition, machine learning analyses indicated that prestimulus alpha power and its correlation with RT could serve as features to distinguish older adults with MCI from HCs and to predict performance on some neuropsychological tests. Conclusion: The reduced correlation between prestimulus alpha activity and RT suggests that older adults with MCI experience impaired preparatory attention.
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Affiliation(s)
- Yiqi Chen
- Center for Brain Disorders and Cognitive Sciences, Shenzhen University, Shenzhen, China.,School of Psychology, Shenzhen University, Shenzhen, China
| | - Hao He
- Center for Brain Disorders and Cognitive Sciences, Shenzhen University, Shenzhen, China.,School of Psychology, Shenzhen University, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Center for Neuroimaging, Shenzhen Institute of Neuroscience, Shenzhen, China
| | - Pengfei Xu
- Center for Brain Disorders and Cognitive Sciences, Shenzhen University, Shenzhen, China.,School of Psychology, Shenzhen University, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Center for Neuroimaging, Shenzhen Institute of Neuroscience, Shenzhen, China
| | - Jing Wang
- Center for Brain Disorders and Cognitive Sciences, Shenzhen University, Shenzhen, China.,School of Psychology, Shenzhen University, Shenzhen, China
| | - Yuehong Qiu
- Center for Brain Disorders and Cognitive Sciences, Shenzhen University, Shenzhen, China.,School of Psychology, Shenzhen University, Shenzhen, China
| | - Wei Feng
- School of Marxism, Jilin Medical University, Jilin, China
| | - Yuejia Luo
- Center for Brain Disorders and Cognitive Sciences, Shenzhen University, Shenzhen, China.,School of Psychology, Shenzhen University, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Center for Neuroimaging, Shenzhen Institute of Neuroscience, Shenzhen, China
| | - Li Hu
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Qing Guan
- Center for Brain Disorders and Cognitive Sciences, Shenzhen University, Shenzhen, China.,School of Psychology, Shenzhen University, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Center for Neuroimaging, Shenzhen Institute of Neuroscience, Shenzhen, China
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8
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He M, Heindel WC, Nassar MR, Siefert EM, Festa EK. Age-related changes in the functional integrity of the phasic alerting system: a pupillometric investigation. Neurobiol Aging 2020; 91:136-147. [PMID: 32224065 DOI: 10.1016/j.neurobiolaging.2020.02.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 01/08/2023]
Abstract
Enhanced processing following a warning cue is thought to be mediated by a phasic alerting response involving the locus coeruleus-noradrenergic (LC-NA) system. We examined the effect of aging on phasic alerting using pupil dilation as a marker of LC-NA activity in conjunction with a novel assessment of task-evoked pupil dilation. While both young and older adults displayed behavioral and pupillary alerting effects, reflected in decreased RT and increased pupillary response under high (tone) versus low (no tone) alerting conditions, older adults displayed a weaker pupillary response that benefited more from the alerting tone. The strong association between dilation and speed displayed by older adults in both alerting conditions was reduced in young adults in the high alerting condition, suggesting that in young (but not older) adults the tone conferred relatively little behavioral benefit beyond that provided by the alerting effect elicited by the target. These findings suggest a functioning but deficient LC-NA alerting system in older adults, and help reconcile previous results concerning the effects of aging on phasic alerting.
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Affiliation(s)
- Mingjian He
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA
| | - William C Heindel
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA
| | - Matthew R Nassar
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA
| | - Elizabeth M Siefert
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA
| | - Elena K Festa
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA.
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9
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Medications influencing central cholinergic pathways affect fixation stability, saccadic response time and associated eye movement dynamics during a temporally-cued visual reaction time task. Psychopharmacology (Berl) 2017; 234:671-680. [PMID: 27988806 DOI: 10.1007/s00213-016-4507-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 12/05/2016] [Indexed: 10/20/2022]
Abstract
RATIONALE Anticholinergic medications largely exert their effects due to actions on the muscarinic receptor, which mediates the functions of acetylcholine in the peripheral and central nervous systems. In the central nervous system, acetylcholine plays an important role in the modulation of movement. OBJECTIVE This study investigated the effects of over-the-counter medications with varying degrees of central anticholinergic properties on fixation stability, saccadic response time and the dynamics associated with this eye movement during a temporally-cued visual reaction time task, in order to establish the significance of central cholinergic pathways in influencing eye movements during reaction time tasks. METHODS Twenty-two participants were recruited into the placebo-controlled, human double-blind, four-way crossover investigation. Eye tracking technology recorded eye movements while participants reacted to visual stimuli following temporally informative and uninformative cues. The task was performed pre-ingestion as well as 0.5 and 2 h post-ingestion of promethazine hydrochloride (strong centrally acting anticholinergic), hyoscine hydrobromide (moderate centrally acting anticholinergic), hyoscine butylbromide (anticholinergic devoid of central properties) and a placebo. RESULTS Promethazine decreased fixation stability during the reaction time task. In addition, promethazine was the only drug to increase saccadic response time during temporally informative and uninformative cued trials, whereby effects on response time were more pronounced following temporally informative cues. Promethazine also decreased saccadic amplitude and increased saccadic duration during the temporally-cued reaction time task. CONCLUSION Collectively, the results of the study highlight the significant role that central cholinergic pathways play in the control of eye movements during tasks that involve stimulus identification and motor responses following temporal cues.
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Martella D, Manzanares S, Campoy G, Roca J, Antúnez C, Fuentes LJ. Phasic and tonic alerting in mild cognitive impairment: A preliminary study. Exp Gerontol 2014; 49:35-9. [DOI: 10.1016/j.exger.2013.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/07/2013] [Accepted: 11/11/2013] [Indexed: 10/26/2022]
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McLaughlin PM, Anderson ND, Rich JB, Chertkow H, Murtha SJE. Visual selective attention in amnestic mild cognitive impairment. J Gerontol B Psychol Sci Soc Sci 2013; 69:881-91. [PMID: 23974434 DOI: 10.1093/geronb/gbt077] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Subtle deficits in visual selective attention have been found in amnestic mild cognitive impairment (aMCI). However, few studies have explored performance on visual search paradigms or the Simon task, which are known to be sensitive to disease severity in Alzheimer's patients. Furthermore, there is limited research investigating how deficiencies can be ameliorated with exogenous support (auditory cues). METHOD Sixteen individuals with aMCI and 14 control participants completed 3 experimental tasks that varied in demand and cue availability: visual search-alerting, visual search-orienting, and Simon task. RESULTS Visual selective attention was influenced by aMCI, auditory cues, and task characteristics. Visual search abilities were relatively consistent across groups. The aMCI participants were impaired on the Simon task when working memory was required, but conflict resolution was similar to controls. Spatially informative orienting cues improved response times, whereas spatially neutral alerting cues did not influence performance. Finally, spatially informative auditory cues benefited the aMCI group more than controls in the visual search task, specifically at the largest array size where orienting demands were greatest. DISCUSSION These findings suggest that individuals with aMCI have working memory deficits and subtle deficiencies in orienting attention and rely on exogenous information to guide attention.
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Affiliation(s)
| | - Nicole D Anderson
- Rotman Research Institute, Baycrest, Toronto, Ontario, Canada. Departments of Psychiatry and Psychology, University of Toronto, Ontario, Canada
| | - Jill B Rich
- Department of Psychology, York University, Toronto, Ontario, Canada
| | - Howard Chertkow
- Department of Neurology and Neurosurgery and Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, McGill University, Montreal, Quebec, Canada
| | - Susan J E Murtha
- Department of Psychology, York University, Toronto, Ontario, Canada.
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12
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Does a paper's country of origin affect the length of the review process? Cortex 2012; 48:945-51. [DOI: 10.1016/j.cortex.2012.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 05/25/2012] [Indexed: 11/20/2022]
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13
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Foley JA, Valkonen L. Are higher cited papers accepted faster for publication? Cortex 2012; 48:647-53. [DOI: 10.1016/j.cortex.2012.03.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 03/23/2012] [Indexed: 10/28/2022]
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14
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Asymmetric loss of parietal activity causes spatial bias in prodromal and mild Alzheimer's disease. Biol Psychiatry 2012; 71:798-804. [PMID: 22079258 DOI: 10.1016/j.biopsych.2011.09.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 09/19/2011] [Accepted: 09/20/2011] [Indexed: 11/23/2022]
Abstract
BACKGROUND In Alzheimer's disease (AD), loss of effective neuronal activity is reflected by cortical glucose hypometabolism. Hypometabolism in the posterior parietal cortex (PPC) is among the first in vivo signs of AD; however, its functional impact on large-scale brain mechanisms and behavior is poorly understood. The lateral PPC contributes to spatial attention constituting a basic function of the human brain. We hypothesized 1) that lateral PPC hypometabolism is associated with impaired spatial attention in very early AD and 2) that impaired competition of effective neuronal activity across hemispheres might underlie this deficit in terms of brain mechanisms. METHODS A model-based imaging approach was applied to assess patients with prodromal (n = 28) and mild (n = 7) AD. Quantitative attention parameters, derived from performance on simple psychophysical tasks and analyzed by Bundesen's computational theory of visual attention, were related to brain metabolism, measured by (18)F-fluorodeoxyglucose positron emission tomography. RESULTS Patients' left and right lateral PPC metabolism was reduced. Nine patients had significant spatial attentional bias on the left side and two patients on the right. Direction and degree of spatial bias was correlated with direction and degree of an interhemispheric metabolism bias in the inferior parietal lobe and temporoparietal junction. CONCLUSIONS Our data provide evidence that in very early AD, asymmetric hypometabolism of the lateral PPC causes spatial attentional bias. Results are broadly consistent with the model that asymmetrically impaired effective neuronal PPC activity in AD biases the competition of visual objects for cortical representation and access to awareness to one side.
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