1
|
Aziz JR, Good SR, Horne SC, Eskes GA. A scoping review and critique of the Input-Output subtyping dimension of spatial neglect. Cortex 2024; 176:11-36. [PMID: 38729033 DOI: 10.1016/j.cortex.2024.04.005] [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: 10/22/2023] [Revised: 02/28/2024] [Accepted: 04/22/2024] [Indexed: 05/12/2024]
Abstract
Spatial neglect is a common and debilitating disorder after stroke whereby individuals have difficulty reporting, orienting, and/or responding to the contralesional side of space. Given the heterogeneity of neglect symptom presentation, various neglect subtypes have been proposed to better characterize the disorder. This review focuses on the distinction between Input neglect (i.e., difficulty perceiving and/or attending to contralesional stimuli) and Output neglect (i.e., difficulty planning and/or executing movements toward contralesional stimuli). Conceptualizations of Input and Output neglect have varied considerably. We provide a novel summary of the terminology, measurement approaches, and neural correlates of these subtypes. A protocol detailing our systematic scoping review strategy is registered on the Open Science Framework (https://osf.io/bvtxf/). For feasibility and greater comparability across studies, we limited our inclusion criteria to tasks focused on visual stimuli and upper-limb movements. A total of 110 articles were included in the review. Subtyping tasks were categorized based on whether they mainly manipulated aspects of the input (i.e., congruence of visual input with motor output, presence of visual input) or the output (i.e., modality, goal, or direction of output) to produce an Input-Output subtype dissociation. We used our review results to identify four main critiques of this literature: 1) lack of consistency/clarity in conceptual models; 2) methodological issues of dissociating Input and Output subtypes; 3) a need for updated neural theories; and 4) barriers to clinical application. We discuss the lessons learned from this subtyping dimension that can be applied to future research on neglect subtype assessment and treatment.
Collapse
Affiliation(s)
- Jasmine R Aziz
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Canada.
| | - Samantha R Good
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Canada
| | - Samantha C Horne
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Canada; Faculty of Medicine, Dalhousie University, Halifax, Canada
| | - Gail A Eskes
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Canada; Department of Psychiatry, Dalhousie University, Halifax, Canada
| |
Collapse
|
2
|
Barrett AM, Goedert KM, Carter AR, Chaudhari A. Spatial neglect treatment: The brain's spatial-motor Aiming systems. Neuropsychol Rehabil 2022; 32:662-688. [PMID: 33941021 PMCID: PMC9632633 DOI: 10.1080/09602011.2020.1862678] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 10/29/2020] [Indexed: 10/21/2022]
Abstract
Animal and human literature supports spatial-motor "Aiming" bias, a frontal-subcortical syndrome, as a core deficit in spatial neglect. However, spatial neglect treatment studies rarely assess Aiming errors. Two knowledge gaps result: spatial neglect rehabilitation studies fail to capture the impact on motor-exploratory aspects of functional disability. Also, across spatial neglect treatment studies, discrepant treatment effects may also result from sampling different proportions of patients with Aiming bias. We review behavioural evidence for Aiming spatial neglect, and demonstrate the importance of measuring and targeting Aiming bias for treatment, by reviewing literature on Aiming spatial neglect and prism adaptation treatment, and presenting new preliminary data on bromocriptine treatment. Finally, we review neuroanatomical and network disruption that may give rise to Aiming spatial neglect. Because Aiming spatial neglect predicts prism adaptation treatment response, assessment may broaden the ability of rehabilitation research to capture functionally-relevant disability. Frontal brain lesions predict both the presence of Aiming spatial neglect, and a robust response to some spatial neglect interventions. Research is needed that co-stratifies spatial neglect patients by lesion location and Aiming spatial neglect, to personalize spatial neglect rehabilitation and perhaps even open a path to spatial retraining as a means of promoting better mobility after stroke.
Collapse
Affiliation(s)
- A M Barrett
- Neurorehabilitation Division, Emory Brain Health Center, and Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Health System, Decatur, GA, USA
| | - Kelly M Goedert
- Department of Psychology, Seton Hall University, South Orange, NJ, USA
| | - Alexandre R Carter
- Neurorehabilitation Division, Department of Neurology, Washington University School of Medicine, Saint Louis, MO, USA
- Program in Occupational Therapy, Washington University in Saint Louis, Saint Louis, MO, USA
| | - Amit Chaudhari
- Department of Neurology, University of California Irvine, Irvine, CA, USA
| |
Collapse
|
3
|
Abdou A, Pilkar R, Chen P, Yue G, Barrett A. Improved stability of long-duration sitting in spatial neglect after a single session of prism adaptation. Neurocase 2020; 26:201-210. [PMID: 32600098 DOI: 10.1080/13554794.2020.1786134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Spatial neglect after right brain stroke affects balance, and improvements in sitting balance after prism adaptation have been demonstrated using short-duration center of pressure (CoP) data. We present long-duration (5 min) CoP and trunk muscles electromyography recordings of a 61-year-old man with left-sided spatial neglect, before and after a single session of prism adaptation. His CoP-derived measures showed improved balance and postural stability in both the anterior-posterior and medial-lateral directions after prism adaptation. Concurrently, asymmetry in neuromuscular activations was reduced. The findings suggest that improved sitting balance may be associated with more symmetrical activation of trunk muscles after prism adaptation.
Collapse
Affiliation(s)
- Andrew Abdou
- Burke Rehabilitation Hospital , White Plains, NY, USA.,Department of Physical Medicine & Rehabilitation, Montefiore Medical Center , Bronx, NY, USA.,The Arthur S. Abramson Department of Rehabilitation Medicine, Albert Einstein College of Medicine , Bronx, NY, USA
| | - Rakesh Pilkar
- Center for Mobility and Rehabilitation Engineering Research, Kessler Foundation , West Orange, NJ, USA.,eDepartment of Physical Medicine & Rehabilitation, Rutgers - New Jersey Medical School , Newark, NJ, USA
| | - Peii Chen
- eDepartment of Physical Medicine & Rehabilitation, Rutgers - New Jersey Medical School , Newark, NJ, USA.,Center for Stroke Rehabilitation Research, Kessler Foundation , West Orange, NJ, USA
| | - Guang Yue
- Center for Mobility and Rehabilitation Engineering Research, Kessler Foundation , West Orange, NJ, USA.,eDepartment of Physical Medicine & Rehabilitation, Rutgers - New Jersey Medical School , Newark, NJ, USA
| | - A Barrett
- Department of Neurology, Emory School of Medicine , Atlanta, GA, USA.,Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center , Decatur, GA, USA
| |
Collapse
|
4
|
Ciricugno A, Rinaldi L, Vecchi T, Merabet LB, Cattaneo Z. The Role of Binocular Vision in Driving Pseudoneglect in Visual and Haptic Bisection: Evidence From Strabismic and Monocular Blind Individuals. Multisens Res 2020; 33:549-567. [PMID: 31059488 DOI: 10.1163/22134808-20191347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/07/2019] [Indexed: 11/19/2022]
Abstract
Prior studies have shown that strabismic amblyopes do not exhibit pseudoneglect in visual line bisection, suggesting that the right-hemisphere dominance in the control of spatial attention may depend on a normally developing binocular vision. In this study, we aimed to investigate whether an abnormal binocular childhood experience also affects spatial attention in the haptic modality, thus reflecting a supramodal effect. To this aim, we compared the performance of normally sighted, strabismic and early monocular blind participants in a visual and a haptic line bisection task. In visual line bisection, strabismic individuals tended to err to the right of the veridical midpoint, in contrast with normally sighted participants who showed pseudoneglect. Monocular blind participants exhibited high variability in their visual performance, with a tendency to bisect toward the direction of the functioning eye. In turn, in haptic bisection, all participants consistently erred towards the left of the veridical midpoint. Taken together, our findings support the view that pseudoneglect in the visual and haptic modality relies on different functional and neural mechanisms.
Collapse
Affiliation(s)
- Andrea Ciricugno
- 1Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Luca Rinaldi
- 2Department of Psychology, University of Milano-Bicocca, Milan, Italy.,3NeuroMI, Milan Center for Neuroscience, Milan, Italy
| | - Tomaso Vecchi
- 1Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.,4IRCCS Mondino Foundation, Pavia, Italy
| | - Lotfi B Merabet
- 5The Laboratory for Visual Neuroplasticity, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, USA
| | - Zaira Cattaneo
- 2Department of Psychology, University of Milano-Bicocca, Milan, Italy.,4IRCCS Mondino Foundation, Pavia, Italy
| |
Collapse
|
5
|
Abstract
PURPOSE OF REVIEW Spatial neglect is asymmetric orienting and action after a brain lesion, causing functional disability. It is common after a stroke; however, it is vastly underdocumented and undertreated. This article addresses the implementation gap in identifying and treating spatial neglect, to reduce disability and improve healthcare costs and burden. RECENT FINDINGS Professional organizations published recommendations to implement spatial neglect care. Physicians can lead an interdisciplinary team: functionally relevant spatial neglect assessment, evidence-based spatial retraining, and integrated spatial and vision interventions can optimize outcomes. Research also strongly suggests spatial neglect adversely affects motor systems. Spatial neglect therapy might thus "kick-start" rehabilitation and improve paralysis recovery. Clinicians can implement new techniques to detect spatial neglect and lead interdisciplinary teams to promote better, integrated spatial neglect care. Future studies of brain imaging biomarkers to detect spatial neglect, and real-world applicability of prism adaptation treatment, are needed.
Collapse
Affiliation(s)
- A M Barrett
- Stroke Rehabilitation Research, Kessler Foundation, East Hanover, NJ, USA.
| | - K E Houston
- Harvard Medical School, Department of Ophthalmology, Spaulding Rehabilitation Hospital, Boston, MA, USA
| |
Collapse
|
6
|
de Best PB, Raz N, Dumoulin SO, Levin N. How Ocular Dominance and Binocularity Are Reflected by the Population Receptive Field Properties. Invest Ophthalmol Vis Sci 2018; 59:5301-5311. [PMID: 30398621 DOI: 10.1167/iovs.18-24161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The neural substrate of binocularity and sighting ocular dominance in humans is not clear. By utilizing the population receptive field (pRF) modeling technique, we explored whether these phenomena are associated with amplitude and pRF size differences. Methods The visual field maps of 13 subjects were scanned (3-T Skyra) while viewing drifting bar stimuli. Both eyes (binocular condition), the dominant eye and the nondominant eye (two monocular conditions) were stimulated in separate sessions. For each condition, pRF size and amplitude were assessed. Binocular summation ratios were calculated by dividing binocular by mean monocular values (amplitude and pRF size). Results No differences in pRF size were seen between the viewing conditions within each region, that is, either between binocular and monocular or between dominant and nondominant viewing conditions. Binocular amplitudes were higher than the monocular amplitudes, but similar among the dominant and nondominant eyes. Binocular summation ratios derived from amplitudes were significantly higher than one (∼1.2), while those ratios derived from pRF size were not. These effects were found in all studied areas along the visual hierarchy, starting in V1. Conclusions Neither the amplitude nor the pRF size show intereye difference and therefore cannot explain the different roles of the dominant and the nondominant eyes. Binocular, as compared to monocular vision, resulted in higher amplitudes, while receptive fields' sizes were similar, suggesting increased binocular response intensity as the basis for the binocular summation phenomenon. Our results could be applicable in imaging studies of monocular disease and studies that deal with nondisparity binocularity effects.
Collapse
Affiliation(s)
- Pieter B de Best
- fMRI lab, Neurology Department, Hadassah Hebrew University Medical Center Jerusalem, Israel
| | - Noa Raz
- fMRI lab, Neurology Department, Hadassah Hebrew University Medical Center Jerusalem, Israel
| | | | - Netta Levin
- fMRI lab, Neurology Department, Hadassah Hebrew University Medical Center Jerusalem, Israel
| |
Collapse
|
7
|
Abstract
PURPOSE Patching for double vision is a common palliative treatment for head-trauma patients with acquired strabismus when prisms are not feasible. METHODS We review literature on spatial neglect and discuss possible effects of monocular occlusion on spatial attention. RESULTS Patching the left eye has been shown to worsen spatial judgments in some brain-injured patients with left neglect by inhibiting the right superior colliculus further impairing contralateral leftward orienting (the Sprague Effect). CONCLUSIONS Because more peripheral parts of the visual field increasingly project to the contralateral superior colliculus with the temporal crescent being entirely contralateral, avoiding patching of the temporal crescent was advised, and in most cases can be achieved by taping off the spectacle lens and avoiding an elastic eye patch.
Collapse
|
8
|
Wagner D, Eslinger PJ, Barrett AM. Decreased leftward 'aiming' motor-intentional spatial cuing in traumatic brain injury. Neuropsychology 2017; 30:731-741. [PMID: 27571220 DOI: 10.1037/neu0000252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
OBJECTIVE To characterize the mediation of attention and action in space following traumatic brain injury (TBI). METHOD Two exploratory analyses were performed to determine the influence of spatial 'Aiming' motor versus spatial 'Where' bias on line bisection in TBI participants. The first experiment compared performance according to severity and location of injury in TBI. The second experiment examined bisection performance in a larger TBI sample against a matched control group. In both experiments, participants bisected lines in near and far space using an apparatus that allowed for the fractionation of spatial Aiming versus Where error components. RESULTS In the first experiment, participants with severe injuries tended to incur rightward error when starting from the right in far space, compared with participants with mild injuries. In the second experiment, when performance was examined at the individual level, more participants with TBI tended to incur rightward motor error compared to controls. CONCLUSIONS TBI may cause frontal-subcortical cognitive dysfunction and asymmetric motor perseveration, affecting spatial Aiming bias on line bisection. Potential effects on real-world function need further investigation. (PsycINFO Database Record
Collapse
Affiliation(s)
- Daymond Wagner
- Department of Neurology, Milton S. Hershey Medical Center
| | - Paul J Eslinger
- Departments of Neurology, Neural & Behavioral Sciences, Pediatrics, and Radiology, Penn State College of Medicine
| | - A M Barrett
- Stroke Rehabilitation Research, Kessler Foundation, Departments of Physical Medicine and Rehabilitation/Neurology and Neurosciences, Rutgers/New Jersey Medical School
| |
Collapse
|
9
|
Abstract
Visual impairments are common after traumatic brain injury (TBI) and negatively affect quality of life. We describe a 39-year-old woman with a severe TBI who was evaluated by the inpatient optometry and vision rehabilitation service with findings of complete right homonymous hemianopia and right cranial nerve III palsy with 30-degree right exotropia (eye turn out) and complete right ptosis (eyelid will not open). The 30-degree exotropia advantageously generated 30 degrees of right visual field expansion when the right ptosis was treated with a magnetic levator prosthesis, which restores eyelid opening. Once opened, the patient used visual field expansion derived from a right exotropia to overcome functional impairments caused by right hemianopia. Field expansion improved the patient's wheelchair mobility and reaching tasks during inpatient therapy. This is the first report of visual field expansion by strabismus facilitated by correction of ptosis. Strabismus should be considered for its potential field expansion benefits when homonymous visual deficits are present, before considering patching. A multidisciplinary vision rehabilitation team is well suited to make this determination.
Collapse
|
10
|
Studying the neural bases of prism adaptation using fMRI: A technical and design challenge. Behav Res Methods 2016; 49:2031-2043. [DOI: 10.3758/s13428-016-0840-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
11
|
Chen P, Goedert KM, Shah P, Foundas AL, Barrett AM. Integrity of medial temporal structures may predict better improvement of spatial neglect with prism adaptation treatment. Brain Imaging Behav 2015; 8:346-58. [PMID: 22941243 DOI: 10.1007/s11682-012-9200-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Prism adaptation treatment (PAT) is a promising rehabilitative method for functional recovery in persons with spatial neglect. Previous research suggests that PAT improves motor-intentional "aiming" deficits that frequently occur with frontal lesions. To test whether presence of frontal lesions predicted better improvement of spatial neglect after PAT, the current study evaluated neglect-specific improvement in functional activities (assessment with the Catherine Bergego Scale) over time in 21 right-brain-damaged stroke survivors with left-sided spatial neglect. The results demonstrated that neglect patients' functional activities improved after two weeks of PAT and continued improving for four weeks. Such functional improvement did not occur equally in all of the participants: Neglect patients with lesions involving the frontal cortex (n = 13) experienced significantly better functional improvement than did those without frontal lesions (n = 8). More importantly, voxel-based lesion-behavior mapping (VLBM) revealed that in comparison to the group of patients without frontal lesions, the frontal-lesioned neglect patients had intact regions in the medial temporal areas, the superior temporal areas, and the inferior longitudinal fasciculus. The medial cortical and subcortical areas in the temporal lobe were especially distinguished in the "frontal lesion" group. The findings suggest that the integrity of medial temporal structures may play an important role in supporting functional improvement after PAT.
Collapse
Affiliation(s)
- Peii Chen
- Kessler Foundation Research Center, 1199 Pleasant Valley Way, West Orange, NJ, 07052, USA,
| | | | | | | | | |
Collapse
|
12
|
Loetscher T, Nicholls MER, Brodtmann A, Thomas NA, Brugger P. Disentangling input and output-related components of spatial neglect. Front Hum Neurosci 2012; 6:176. [PMID: 22707937 PMCID: PMC3374575 DOI: 10.3389/fnhum.2012.00176] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/29/2012] [Indexed: 11/13/2022] Open
Abstract
Spatial neglect is a heterogeneous disorder with a multitude of manifestations and subtypes. Common clinical paper and pencil neglect tests fail to differentiate between these subtypes. For example, neglect patients typically bisect lines to the right. This bias can be caused by an underestimation of the left half of the line (input-related deficit), by the failure to direct actions toward the left side of space (output-related deficit), or by a mixture of these impairments. To disentangle these impairments, we used a test consisting of a line bisection task on a touch screen monitor (manual motor task) and the subsequent judgment of one's own bisection performance (visual perceptual task). It was hypothesized that patients with mainly output-related neglect should be better able to recognize their misbisected lines than patients with purely input-related neglect. In a group of 16 patients suffering from spatial neglect after right brain damage, we found that patients were three times more likely to suffer from a predominantly input-related than from an output-related subtype. The results thus suggest that neglect is typically an input-related impairment. Additional analysis of the line bisection task revealed that temporal (slowness in initiation and execution of contralateral movements) and spatial (insufficient movement amplitude toward the contralesional side) aspects of output-related neglect were mutually unrelated. This independence raises the possibility that a fine-grained differentiation of output-related neglect is required. That is, impairments in lateralized temporal and spatial aspects of movements may underlie different neglect subtypes.
Collapse
Affiliation(s)
- Tobias Loetscher
- School of Psychology, Flinders University, AdelaideSA, Australia
- Department of Neurology, University Hospital ZurichZurich, Switzerland
| | | | | | - Nicole A. Thomas
- School of Psychology, Flinders University, AdelaideSA, Australia
| | - Peter Brugger
- Department of Neurology, University Hospital ZurichZurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP)Zurich, Switzerland
| |
Collapse
|
13
|
Hoover AEN, Harris LR, Steeves JKE. Sensory compensation in sound localization in people with one eye. Exp Brain Res 2011; 216:565-74. [DOI: 10.1007/s00221-011-2960-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 11/15/2011] [Indexed: 11/30/2022]
|
14
|
Fortis P, Goedert KM, Barrett AM. Prism adaptation differently affects motor-intentional and perceptual-attentional biases in healthy individuals. Neuropsychologia 2011; 49:2718-27. [PMID: 21663753 DOI: 10.1016/j.neuropsychologia.2011.05.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 05/18/2011] [Accepted: 05/24/2011] [Indexed: 10/18/2022]
Abstract
Prism adaptation (PA) has been shown to affect performance on a variety of spatial tasks in healthy individuals and neglect patients. However, little is still known about the mechanisms through which PA affects spatial cognition. In the present study we tested the effect of PA on the perceptual-attentional "where" and motor-intentional "aiming" spatial systems in healthy individuals. Eighty-four participants performed a line bisection task presented on a computer screen under normal or right-left reversed viewing conditions, which allows for the fractionation of "where" and "aiming" bias components (Schwartz et al., 1997). The task was performed before and after a short period of visuomotor adaptation either to left- or right-shifting prisms, or control goggles fitted with plain glass lenses. Participants demonstrated initial leftward "where" and "aiming" biases, consistent with previous research. Adaptation to left-shifting prisms reduced the leftward motor-intentional "aiming" bias. By contrast, the "aiming" bias was unaffected by adaptation to the right-shifting prisms or control goggles. The leftward "where" bias was also reduced, but this reduction was independent of the direction of the prismatic shift. These results mirror recent findings in neglect patients, who showed a selective amelioration of right motor-intentional "aiming" bias after right prism exposure (Fortis et al., 2009; C.L. Striemer & J. Danckert, 2010). Thus, these findings indicate that prism adaptation primarily affects the motor-intentional "aiming" system in both healthy individuals and neglect patients, and further suggest that improvement in neglect patients after PA may be related to changes in the aiming spatial system.
Collapse
Affiliation(s)
- Paola Fortis
- Neuropsychological Laboratory, IRCCS Italian Auxologico Institute, Milano, Italy.
| | | | | |
Collapse
|
15
|
Abstract
Patterns of cerebral asymmetry related to visuospatial functions may change with age. The typical leftward bias on a line bisection task may reflect cerebral asymmetry. With age, such leftward bias decreases. This study demonstrated that the age-related decrease of leftward bias may actually be sex-specific. In addition, previous research suggests that young adults' deviation in line bisection may reflect asymmetric hemispheric activation of perceptual-attentional "where" spatial systems, rather than motor-intentional "aiming" spatial systems; thus, we specifically fractionated "where" and "aiming" bias of men and women ranging in age from 22 to 93 years old. We observed that older men produced greater rightward line bisection errors, of primarily "where" spatial character. However, women's errors remained leftward biased, and did not significantly change with age. "Where" spatial systems may be linked to cortico-cortical processing networks involving the posterior part of the dorsal visuospatial processing stream. Thus, the current results are consistent with the conclusion that reduced right dorsal spatial activity in aging may occur in the male, but not female, adult spatial system development.
Collapse
|