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Rinaldi L, Ciricugno A, Merabet LB, Vecchi T, Cattaneo Z. The Effect of Blindness on Spatial Asymmetries. Brain Sci 2020; 10:brainsci10100662. [PMID: 32977398 PMCID: PMC7597958 DOI: 10.3390/brainsci10100662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/11/2020] [Accepted: 09/18/2020] [Indexed: 11/27/2022] Open
Abstract
The human cerebral cortex is asymmetrically organized with hemispheric lateralization pervading nearly all neural systems of the brain. Whether the lack of normal visual development affects hemispheric specialization subserving the deployment of visuospatial attention asymmetries is controversial. In principle, indeed, the lack of early visual experience may affect the lateralization of spatial functions, and the blind may rely on a different sensory input compared to the sighted. In this review article, we thus present a current state-of-the-art synthesis of empirical evidence concerning the effects of visual deprivation on the lateralization of various spatial processes (i.e., including line bisection, mirror symmetry, and localization tasks). Overall, the evidence reviewed indicates that spatial processes are supported by a right hemispheric network in the blind, hence, analogously to the sighted. Such a right-hemisphere dominance, however, seems more accentuated in the blind as compared to the sighted as indexed by the greater leftward bias shown in different spatial tasks. This is possibly the result of the more pronounced involvement of the right parietal cortex during spatial tasks in blind individuals compared to the sighted, as well as of the additional recruitment of the right occipital cortex, which would reflect the cross-modal plastic phenomena that largely characterize the blind brain.
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Affiliation(s)
- Luca Rinaldi
- Department of Brain and Behavioural Science, University of Pavia, Piazza Botta 6, 27100 Pavia, Italy;
- Correspondence:
| | | | - Lotfi B. Merabet
- The Laboratory for Visual Neuroplasticity, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02115, USA;
| | - Tomaso Vecchi
- Department of Brain and Behavioural Science, University of Pavia, Piazza Botta 6, 27100 Pavia, Italy;
- IRCCS Mondino Foundation, 27100 Pavia, Italy; (A.C.); (Z.C.)
| | - Zaira Cattaneo
- IRCCS Mondino Foundation, 27100 Pavia, Italy; (A.C.); (Z.C.)
- Department of Psychology, University of Milano-Bicocca, 20126 Milano, Italy
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Shalev N, Vangkilde S, Neville MJ, Tunbridge EM, Nobre AC, Chechlacz M. Dissociable Catecholaminergic Modulation of Visual Attention: Differential Effects of Catechol-O-Methyltransferase and Dopamine Beta-Hydroxylase Genes on Visual Attention. Neuroscience 2019; 412:175-189. [PMID: 31195057 PMCID: PMC6645579 DOI: 10.1016/j.neuroscience.2019.05.068] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 05/30/2019] [Accepted: 05/31/2019] [Indexed: 01/17/2023]
Abstract
Visual attention enables us to prioritise behaviourally relevant visual information while ignoring distraction. The neural networks supporting attention are modulated by two catecholamines, dopamine and noradrenaline. The current study investigated the effects of single nucleotide polymorphisms in two catecholaminergic genes – COMT (Val158Met) and DBH (444 G/A) – on individual differences in attention functions. Participants (n = 125) were recruited from the Oxford Biobank by genotype-based recall. They were tested on a continuous performance task (sustained attention), a Go/No-Go task (response inhibition), and a task assessing attentional selection in accordance with the Theory of Visual Attention (TVA). We found a significant effect of DBH genotype status on the capacity to maintain attention over time (sustained attention) as measured by the continuous performance task. Furthermore, we demonstrated a significant association between COMT genotype status and effective threshold of visual perception in attentional selection as estimated based on the TVA task performance. No other group differences in attention function were found with respect to the studied genotypes. Overall, our findings provide novel experimental evidence that: (i) dopaminergic and noradrenergic genotypes have dissociable effects on visual attention; (ii) either insufficient or excessive catecholaminergic activity may have equally detrimental effects on sustained attention. Catecholaminergic genotypes have dissociative cognitive effects on visual attention. DBH (444 G/A) polymorphism affects sustained attention. COMT Val158Met polymorphism affects perceptual threshold in visual attention. Both too little and too much catecholamines may detrimentally impact sustained attention.
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Affiliation(s)
- Nir Shalev
- Department of Experimental Psychology, University of Oxford, Oxford, UK; Oxford Centre for Human Brain Activity, University of Oxford, Oxford, UK; Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Signe Vangkilde
- Department of Psychology, Center for Visual Cognition, University of Copenhagen, Copenhagen, Denmark
| | - Matt J Neville
- Oxford NIHR Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, UK; Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Elizabeth M Tunbridge
- Department of Psychiatry, University of Oxford, Oxford, UK; Oxford Health NHS Foundation Trust, Oxford, UK
| | - Anna C Nobre
- Department of Experimental Psychology, University of Oxford, Oxford, UK; Oxford Centre for Human Brain Activity, University of Oxford, Oxford, UK; Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK; Department of Psychiatry, University of Oxford, Oxford, UK
| | - Magdalena Chechlacz
- Department of Experimental Psychology, University of Oxford, Oxford, UK; Centre for Human Brain Health, University of Birmingham, Birmingham, UK; School of Psychology, University of Birmingham, Birmingham, UK; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, USA.
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Schmitz J, Kumsta R, Moser D, Güntürkün O, Ocklenburg S. DNA methylation of dopamine-related gene promoters is associated with line bisection deviation in healthy adults. Sci Rep 2019; 9:5902. [PMID: 30976054 PMCID: PMC6459813 DOI: 10.1038/s41598-019-42553-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/03/2019] [Indexed: 11/09/2022] Open
Abstract
Handedness and language lateralization are the most investigated phenotypes among functional hemispheric asymmetries, i.e. differences in function between the left and the right half of the human brain. Both phenotypes are left hemisphere-dominant, while investigations of the molecular factors underlying right hemisphere-dominant phenotypes are less prominent. In the classical line bisection task, healthy subjects typically show a leftward attentional bias due to a relative dominance of the right hemisphere for visuospatial attention. Based on findings of variations in dopamine-related genes affecting performance in the line bisection task, we first tested whether DNA methylation in non-neuronal tissue in the promoter regions of DBH, SLC6A3, and DRD2 are associated with line bisection deviation. We replicated the typical behavioral pattern and found an effect of DNA methylation in the DBH promoter region on line bisection deviation in right-aligned trials. A second exploratory analysis indicated that an overall DNA methylation profile of genes involved in dopamine function predicts line bisection performance in right-aligned trials. Genetic variation in dopamine-related genes has been linked to attention deficit hyperactivity disorder (ADHD), a neurodevelopmental trait associated with rightward attentional bias. Overall, our findings point towards epigenetic markers for functional hemispheric asymmetries in non-neuronal tissue not only for left hemisphere-dominant, but also for right hemisphere-dominant phenotypes.
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Affiliation(s)
- Judith Schmitz
- Biopsychology, Institute of Cognitive Neuroscience, Department of Psychology, Ruhr University, Bochum, Germany.
| | - Robert Kumsta
- Genetic Psychology, Department of Psychology, Ruhr University, Bochum, Germany
| | - Dirk Moser
- Genetic Psychology, Department of Psychology, Ruhr University, Bochum, Germany
| | - Onur Güntürkün
- Biopsychology, Institute of Cognitive Neuroscience, Department of Psychology, Ruhr University, Bochum, Germany
| | - Sebastian Ocklenburg
- Biopsychology, Institute of Cognitive Neuroscience, Department of Psychology, Ruhr University, Bochum, Germany
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Friedrich TE, Elias LJ, Hunter PV. Crashing Left vs. Right: Examining Navigation Asymmetries Using the SHRP2 Naturalistic Driving Study Data. Front Psychol 2018; 8:2153. [PMID: 29312040 PMCID: PMC5733005 DOI: 10.3389/fpsyg.2017.02153] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 11/27/2017] [Indexed: 11/26/2022] Open
Abstract
The magnitude of leftward bias demonstrated in pseudoneglect has been found to differ between younger and older adults in laboratory settings. The objective of this study was to examine the association between age and asymmetries in navigation in a naturalistic setting by examining the frequency of the location of impact on participants' vehicles during crashes and near crashes. The location of impact following crashes and near crashes, and participant's age and gender were retrieved from the SHRP2 NDS database, a large scale naturalistic driving study. Over the course of the study, data were collected from 3,546 participants driving in the United States of America (right-side traffic directionality), which included 1,465 crashes and 2,722 near crashes. During crashes and near crashes, irrespective of age, the location impact was most often on the front side of the participant vehicle. In contrast with results from laboratory environments, age was not associated with the location of impact during crashes and near crashes, and overall, crashes were over-represented on the left side of the vehicle compared to the right. Specifically, crashes were 1.41 times as likely to occur on the left compared to the right side of participants' vehicles. Overall, these findings inform future research that attempts to apply laboratory research, regarding asymmetry in navigation, to naturalistic settings.
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Affiliation(s)
- Trista E Friedrich
- Department of Psychology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Lorin J Elias
- Department of Psychology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Paulette V Hunter
- Department St. Thomas More College, University of Saskatchewan, Saskatoon, SK, Canada
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Thomas NA, Barone AJ, Flew AH, Nicholls ME. Cross-modal influences on attentional asymmetries: Additive effects of attentional orienting and arousal. Neuropsychologia 2017; 96:39-51. [DOI: 10.1016/j.neuropsychologia.2017.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 12/21/2016] [Accepted: 01/04/2017] [Indexed: 11/29/2022]
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The left hemisphere learns what is right: Hemispatial reward learning depends on reinforcement learning processes in the contralateral hemisphere. Neuropsychologia 2016; 89:1-13. [PMID: 27221149 DOI: 10.1016/j.neuropsychologia.2016.05.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 04/19/2016] [Accepted: 05/21/2016] [Indexed: 11/22/2022]
Abstract
Orienting biases refer to consistent, trait-like direction of attention or locomotion toward one side of space. Recent studies suggest that such hemispatial biases may determine how well people memorize information presented in the left or right hemifield. Moreover, lesion studies indicate that learning rewarded stimuli in one hemispace depends on the integrity of the contralateral striatum. However, the exact neural and computational mechanisms underlying the influence of individual orienting biases on reward learning remain unclear. Because reward-based behavioural adaptation depends on the dopaminergic system and prediction error (PE) encoding in the ventral striatum, we hypothesized that hemispheric asymmetries in dopamine (DA) function may determine individual spatial biases in reward learning. To test this prediction, we acquired fMRI in 33 healthy human participants while they performed a lateralized reward task. Learning differences between hemispaces were assessed by presenting stimuli, assigned to different reward probabilities, to the left or right of central fixation, i.e. presented in the left or right visual hemifield. Hemispheric differences in DA function were estimated through differential fMRI responses to positive vs. negative feedback in the left vs. right ventral striatum, and a computational approach was used to identify the neural correlates of PEs. Our results show that spatial biases favoring reward learning in the right (vs. left) hemifield were associated with increased reward responses in the left hemisphere and relatively better neural encoding of PEs for stimuli presented in the right (vs. left) hemifield. These findings demonstrate that trait-like spatial biases implicate hemisphere-specific learning mechanisms, with individual differences between hemispheres contributing to reinforcing spatial biases.
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Thomas NA, Aniulis E, Nicholls ME. The influence of baseline directional differences in pseudoneglect on distractibility. Cortex 2016; 77:69-83. [DOI: 10.1016/j.cortex.2016.01.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 12/24/2015] [Accepted: 01/10/2016] [Indexed: 11/16/2022]
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Ettinger U, Merten N, Kambeitz J. Meta-analysis of the association of the SLC6A3 3'-UTR VNTR with cognition. Neurosci Biobehav Rev 2015; 60:72-81. [PMID: 26593110 DOI: 10.1016/j.neubiorev.2015.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 09/04/2015] [Accepted: 09/24/2015] [Indexed: 12/19/2022]
Abstract
The gene coding for the dopamine transporter (DAT), SLC6A3, contains a 40-base pair variable number of tandem repeats (VNTR) polymorphism (rs28363170) in its 3' untranslated region. This VNTR has been associated with attention deficit hyperactivity disorder (ADHD) and has been investigated in relation to cognition and brain function. Here, we report the results of a comprehensive meta-analysis with meta-regression examining the association of the VNTR with different domains of cognition in healthy adults. We extracted data from 28 independent studies and carried out meta-analyses for associations with working memory (k=10 samples, N=1193 subjects), inhibition (k=8 samples, N=829 subjects), executive functions including inhibition (k=10 samples, N=984 subjects), attention (k=6 samples, N=742 subjects) and declarative long-term memory (k=5 samples, N=251 subjects). None of the investigated dimensions showed significant associations with the VNTR (all p>0.26). Meta-regression including year of publication, gender, age, ethnicity and percentage of 10R-homozygotes similarly did not attain significance. We conclude that there is no evidence that rs28363170 may be a significant predictor of cognitive function in healthy adults.
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Affiliation(s)
- Ulrich Ettinger
- Department of Psychology, University of Bonn, Bonn, Germany.
| | | | - Joseph Kambeitz
- Department of Psychiatry, University of Munich, Munich, Germany
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Zozulinsky P, Greenbaum L, Brande-Eilat N, Braun Y, Shalev I, Tomer R. Dopamine system genes are associated with orienting bias among healthy individuals. Neuropsychologia 2014; 62:48-54. [PMID: 25038551 DOI: 10.1016/j.neuropsychologia.2014.07.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 07/01/2014] [Accepted: 07/09/2014] [Indexed: 01/11/2023]
Abstract
Healthy individuals display subtle orienting bias, manifested as a tendency to direct greater attention toward one hemispace, and evidence suggests that this bias reflects an individual trait, which may be modulated by asymmetric dopamine signaling in striatal and frontal regions. The current study examined the hypothesis that functional genetic variants within dopaminergic genes (DAT1 3' VNTR, dopamine D2 receptor Taq1A (rs1800497) and COMT Val158Met (rs4680)) contribute to individual differences in orienting bias, as measured by the greyscales paradigm, in a sample of 197 young healthy Israeli Jewish participants. For the Taq1A variant, homozygous carriers of the A2 allele displayed significantly increased leftward orienting bias compared to the carriers of the A1 allele. Additionally, and as previously reported by others, we found that bias towards leftward orienting of attention was significantly greater among carriers of the 9-repeat allele of the DAT1 3' VNTR as compared to the individuals who were homozygous for the 10-repeat allele. No significant effect of the COMT Val158Met on orienting bias was found. Taken together, our findings support the potential influence of genetic variants on inter-individual differences in orienting bias, a phenotype relevant to both normal and impaired cognitive processes.
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Affiliation(s)
- Polina Zozulinsky
- Department of Psychology, University of Haifa, 199 Abba Khoushy Ave., Mount Carmel Haifa 3498838, Israel
| | - Lior Greenbaum
- Department of Neurology, Chaim Sheba Medical Center, Tel Hashomer, Hashomer, Israel; The Josheph Sagol Neuroscience center (JSNC), Chaim Sheba Medical Center, Tel Hashomer, Israel
| | - Noa Brande-Eilat
- Department of Psychology, University of Haifa, 199 Abba Khoushy Ave., Mount Carmel Haifa 3498838, Israel
| | - Yair Braun
- Department of Psychology, University of Haifa, 199 Abba Khoushy Ave., Mount Carmel Haifa 3498838, Israel
| | - Idan Shalev
- Department of Biobehavioral Health, Pennsylvania State University, United States
| | - Rachel Tomer
- Department of Psychology, University of Haifa, 199 Abba Khoushy Ave., Mount Carmel Haifa 3498838, Israel.
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Thomas NA, Loetscher T, Nicholls MER. Asymmetries in attention as revealed by fixations and saccades. Exp Brain Res 2014; 232:3253-67. [DOI: 10.1007/s00221-014-4015-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 06/06/2014] [Indexed: 11/28/2022]
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11
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Line bisection in medication-overuse and chronic tension-type headaches. Transl Neurosci 2014. [DOI: 10.2478/s13380-014-0216-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
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Benwell CSY, Thut G, Learmonth G, Harvey M. Spatial attention: differential shifts in pseudoneglect direction with time-on-task and initial bias support the idea of observer subtypes. Neuropsychologia 2013; 51:2747-56. [PMID: 24076376 DOI: 10.1016/j.neuropsychologia.2013.09.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/18/2013] [Indexed: 11/17/2022]
Abstract
Asymmetry in human spatial attention has long been documented. In the general population the majority of individuals tend to misbisect horizontal lines to the left of veridical centre. Nonetheless in virtually all previously reported studies on healthy participants, there have been subsets of people displaying rightward biases. In this study, we report differential time-on task effects depending on participants' initial pseudoneglect bias: participants with an initial left bias in a landmark task (in which they had to judge whether a transection mark appeared closer to the right or left end of a line) showed a significant rightward shift over the course of the experimental session, whereas participants with an initial right bias shifted leftwards. We argue that these differences in initial biases as well as the differential shifts with time-on task reflect genuine observer subtypes displaying diverging behavioural patterns. These observer subtypes could be driven by differences in brain organisation and/or lateralisation such as varying anatomical pathway asymmetries (Thiebaut de Schotten et al., 2011).
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Affiliation(s)
- Christopher S Y Benwell
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow 58 Hillhead Street, G12 8QB, United Kingdom; School of Psychology, University of Glasgow, Glasgow G12 8QB, United Kingdom
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Newman DP, O'Connell RG, Nathan PJ, Bellgrove MA. Dopamine transporter genotype predicts attentional asymmetry in healthy adults. Neuropsychologia 2012; 50:2823-2829. [PMID: 22940645 DOI: 10.1016/j.neuropsychologia.2012.08.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/12/2012] [Accepted: 08/14/2012] [Indexed: 10/28/2022]
Abstract
A number of recent studies suggest that DNA variation in the dopamine transporter gene (DAT1) influences spatial attention asymmetry in clinical populations such as ADHD, but confirmation in non-clinical samples is required. Since non-spatial factors such as attentional load have been shown to influence spatial biases in clinical conditions, here we sought to determine whether any association between DAT1 genotype and spatial bias might be moderated by non-spatial attentional load. Healthy adults were asked to react to sudden onset peripheral targets while demand on non-spatial attention was manipulated via a central task. Participants were genotyped for a DAT1 variable number of tandem repeat (VNTR) polymorphism. The 10-repeat allele of this variant is a replicated susceptibility allele for ADHD and has been shown to associate with spatial bias. As expected, an overall leftward asymmetry/pseudoneglect was observed when the data were averaged across the entire sample. When data were stratified by DAT1 genotype, individuals lacking homozygosity for the 10-repeat DAT1 allele (non-10/10) showed a pronounced leftward bias that was significantly different from zero. In line with past reports from children with ADHD, this leftward bias was attenuated in individuals who were homozygous for the DAT1 10-repeat allele (10/10), suggestive of relatively weaker right hemisphere dominance for spatial attention. This effect of DAT1 genotype on spatial bias was not modulated by non-spatial attention load. These data confirm in healthy adult participants both the existence and the direction of the relationship previously reported between DAT1 genotype and spatial bias in children with ADHD. These data add to a growing body of evidence showing that spatial attentional asymmetry is a stable quantitative trait, with individual differences in this trait significantly predicted by common DNA variation in the DAT1 gene.
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Affiliation(s)
- Daniel P Newman
- Monash University, School of Psychology and Psychiatry, Victoria, Australia.
| | - Redmond G O'Connell
- Trinity College Dublin, School of Psychology and Trinity College Institute of Neuroscience, Dublin, Ireland
| | - Pradeep J Nathan
- Monash University, School of Psychology and Psychiatry, Victoria, Australia; University of Cambridge, Department of Psychiatry, Brain Mapping Unit, Cambridge, United Kingdom; GlaxoSmithKline, Clinical Unit Cambridge, Cambridge, United Kingdom
| | - Mark A Bellgrove
- Monash University, School of Psychology and Psychiatry, Victoria, Australia
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Thomas NA, Loetscher T, Nicholls MER. Central fixations with rightward deviations: saccadic eye movements on the landmark task. Exp Brain Res 2012; 220:29-39. [PMID: 22623091 DOI: 10.1007/s00221-012-3113-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 04/26/2012] [Indexed: 01/08/2023]
Affiliation(s)
- Nicole A Thomas
- School of Psychology, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
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Schmitz R, Peigneux P. Age-related changes in visual pseudoneglect. Brain Cogn 2011; 76:382-9. [PMID: 21536360 DOI: 10.1016/j.bandc.2011.04.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 04/03/2011] [Accepted: 04/11/2011] [Indexed: 10/18/2022]
Abstract
Pseudoneglect is a slight but consistent leftward attentional bias commonly observed in healthy young populations, purportedly explained by right hemispheric dominance. It has been suggested that normal aging might be associated with a decline of the right hemisphere. According to this hypothesis, a few studies have shown that elderly tend to exhibit a rightward attentional bias in line bisection. In the present study, we tested this hypothesis in young and older participants using a perceptual landmark task. Results yield evidence for an age-related shift, from a strong attentional leftward bias in young adults toward a suppressed or even a reversed bias in the elderly. Right hemisphere impairment coupled to a left hemispheric compensation might explain the perceptual shift observed in older adults. However, a decline in corpus callosum function cannot be excluded. Alternatively, these results may be in agreement with the hypothesis of an age-related specific inhibition of return dysfunction, an overt attentional orienting mechanism, and/or a decrease of dopamine.
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Affiliation(s)
- Rémy Schmitz
- UR2NF Unité de Recherches en Neuropsychologie et Neuroimagerie Fonctionnelle, Université Libre de Bruxelles, Campus du Solbosch CP191, Avenue F.D. Roosevelt 50, B-1050 Brussels, Belgium
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Hecht D. Depression and the hyperactive right-hemisphere. Neurosci Res 2010; 68:77-87. [PMID: 20603163 DOI: 10.1016/j.neures.2010.06.013] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 06/24/2010] [Accepted: 06/28/2010] [Indexed: 12/21/2022]
Abstract
Depression is associated with an inter-hemispheric imbalance; a hyperactive right-hemisphere (RH) and a relatively hypoactive left-hemisphere (LH). Nevertheless, the underlying mechanisms which can explain why depression is associated with a RH dominance remain elusive. This article points out the potential links between functional cerebral asymmetries and specific symptoms and features of depression. There is evidence that the RH is selectively involved in processing negative emotions, pessimistic thoughts and unconstructive thinking styles--all which comprise the cognitive phenomenology of depression and in turn contribute to the elevated anxiety, stress and pain associated with the illness. Additionally, the RH mediates vigilance and arousal which may explain the sleep disturbances often reported in depression. The RH had also been linked with self-reflection, accounting for the tendency of depressed individuals to withdraw from their external environments and focus attention inward. Physiologically, RH activation is associated with hyprecortisolemia, which contributes to the deterioration of the immune system functioning and puts depressed patients at a greater risk of developing other illnesses, accounting for depression's high comorbidity with other diseases. Conversely, the LH is specifically involved in processing pleasurable experiences, and its relative attenuation is in line with the symptoms of anhedonia that characterize depression. The LH is also relatively more involved in decision-making processes, accounting for the indecisiveness that is often accompanied with depression.
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Affiliation(s)
- David Hecht
- Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N3AR, UK.
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