scholarly journals Motor role of parietal cortex in a monkey model of hemispatial neglect

2015 ◽  
Vol 112 (16) ◽  
pp. E2067-E2072 ◽  
Author(s):  
Jan Kubanek ◽  
Jingfeng M. Li ◽  
Lawrence H. Snyder
Keyword(s):  
Eye Movements ◽  
Parietal Cortex ◽  
Arm Movements ◽  
Intraparietal Sulcus ◽  
Hemispatial Neglect ◽  
Spatial Choice ◽  
Choice Making ◽  
Monkey Model ◽  
Choice Tasks

Parietal cortex is central to spatial cognition. Lesions of parietal cortex often lead to hemispatial neglect, an impairment of choices of targets in space. It has been unclear whether parietal cortex implements target choice at the general cognitive level, or whether parietal cortex subserves the choice of targets of particular actions. To address this question, monkeys engaged in choice tasks in two distinct action contexts—eye movements and arm movements. We placed focused reversible lesions into specific parietal circuits using the GABAA receptor agonist muscimol and validated the lesion placement using MRI. We found that lesions on the lateral bank of the intraparietal sulcus [lateral intraparietal area (LIP)] specifically biased choices made using eye movements, whereas lesions on the medial bank of the intraparietal sulcus [parietal reach region (PRR)] specifically biased choices made using arm movements. This double dissociation suggests that target choice is implemented in dedicated parietal circuits in the context of specific actions. This finding emphasizes a motor role of parietal cortex in spatial choice making and contributes to our understanding of hemispatial neglect.

scholarly journals Visual working memory representations in visual and parietal cortex do not remap after eye movements

2019 ◽  
Author(s):  
Tao He ◽  
Matthias Ekman ◽  
Annelinde R.E. Vandenbroucke ◽  
Floris P. de Lange
Keyword(s):  
Working Memory ◽  
Visual Cortex ◽  
Eye Movements ◽  
Visual Field ◽  
Visual System ◽  
Visual Working Memory ◽  
Parietal Cortex ◽  
List Type ◽  
Early Visual Cortex

ABSTRACTIt has been suggested that our visual system does not only process stimuli that are directly available to our eyes, but also has a role in maintaining information in VWM over a period of seconds. It remains unclear however what happens to VWM representations in the visual system when we make saccades. Here, we tested the hypothesis that VWM representations are remapped within the visual system after making saccades. We directly compared the content of VWM for saccade and no-saccade conditions using MVPA of delay-related activity measured with fMRI. We found that when participants did not make a saccade, VWM representations were robustly present in contralateral early visual cortex. When making a saccade, VWM representations degraded in contralateral V1-V3 after the saccade shifted the location of the remembered grating to the opposite visual field. However, contrary to our hypothesis we found no evidence for the representations of the remembered grating at the saccadic target location in the opposite visual field, suggesting that there is no evidence for remapping of VWM in early visual cortex. Interestingly, IPS showed persistent VWM representations in both the saccade and no-saccade condition. Together, our results indicate that VWM representations in early visual cortex are not remapped across eye movements, potentially limiting the role of early visual cortex in VWM storage.HighlightsVisual working memory (VWM) representations do not remap after making saccadesEye movement degrade VWM representations in early visual cortex, limiting the role of early visual cortex in VWM storageParietal cortex shows persistent VWM representations across saccades

scholarly journals Role of the human parietal cortex in predictive remapping across eye movements: an online rTMS study.

2016 ◽  
Vol 16 (12) ◽  
pp. 99
Author(s):  
Delphine Levy-Bencheton ◽  
Marc Kamke ◽  
Jason Mattingley
Keyword(s):  
Eye Movements ◽  
Parietal Cortex ◽  
Predictive Remapping

Parietal Cortex and Spatial-Postural Transformation During Arm Movements

1998 ◽  
Vol 79 (1) ◽  
pp. 478-482 ◽  
Author(s):  
M.F.S. Rushworth ◽  
H. Johansen-Berg ◽  
S. A. Young
Keyword(s):  
Parietal Cortex ◽  
Cell Activity ◽  
Arm Movements ◽  
Simple Relation ◽  
Hand Position ◽  
Coordinate Transformations ◽  
Subsequent Transformation ◽  
Movement Selection ◽  
Motor Areas

Rushworth, M.F.S., H. Johansen-Berg, and S. A. Young. Parietal cortex and spatial-postural transformation during arm movements. J. Neurophysiol. 79: 478–482, 1998. Cells in the parietal motor areas 5, MIP, and 7b have spatially tuned activity during movements. Lesions, however, do not disrupt visual reaching or learned nonspatial movement selection. The role of such parietal cells in sensorimotor coordinate transformations is unclear. The present experiment investigates whether the parietal motor areas are concerned with the following: 1) the transformation between the desired position in space of the hand and the limb's postural configuration during movement and 2) interjoint coordination. Six macaque monkeys were trained to reach in the dark. Spatial-postural transformations assume a simple form in the absence of vision and so may be most easily studied when animals reach in the dark. A lesion was placed in the parietal cortex that included areas 5, MIP, and 7b of three macaques. The simple relation between hand position and limb postural configuration seen in controls was disrupted after the lesion. The intercoordination of movements of the hand with those of the rest of the arm was also affected. The lesion did not affect the range or velocity of joint movements or the curvature of the hand's trajectory. The cell activity in parietal areas 5, MIP, and 7b may not be essential for the transformation between retinocentric representation of the target and shoulder centered representations of the desired position of the hand, but it is essential for both the subsequent transformation between desired hand position and the postural configuration of the arm and for interjoint integration.

scholarly journals Role of Primate Cerebellar Hemisphere in Voluntary Eye Movement Control Revealed by Lesion Effects

2009 ◽  
Vol 101 (2) ◽  
pp. 934-947 ◽  
Author(s):  
Masafumi Ohki ◽  
Hiromasa Kitazawa ◽  
Takahito Hiramatsu ◽  
Kimitake Kaga ◽  
Taiko Kitamura ◽  
...  
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Smooth Pursuit ◽  
Movement Control ◽  
Cerebellar Hemisphere ◽  
Target Velocity ◽  
Eye Movement Control ◽  
Pursuit Eye Movements ◽  
Catch Up

The anatomical connection between the frontal eye field and the cerebellar hemispheric lobule VII (H-VII) suggests a potential role of the hemisphere in voluntary eye movement control. To reveal the involvement of the hemisphere in smooth pursuit and saccade control, we made a unilateral lesion around H-VII and examined its effects in three Macaca fuscata that were trained to pursue visually a small target. To the step (3°)-ramp (5–20°/s) target motion, the monkeys usually showed an initial pursuit eye movement at a latency of 80–140 ms and a small catch-up saccade at 140–220 ms that was followed by a postsaccadic pursuit eye movement that roughly matched the ramp target velocity. After unilateral cerebellar hemispheric lesioning, the initial pursuit eye movements were impaired, and the velocities of the postsaccadic pursuit eye movements decreased. The onsets of 5° visually guided saccades to the stationary target were delayed, and their amplitudes showed a tendency of increased trial-to-trial variability but never became hypo- or hypermetric. Similar tendencies were observed in the onsets and amplitudes of catch-up saccades. The adaptation of open-loop smooth pursuit velocity, tested by a step increase in target velocity for a brief period, was impaired. These lesion effects were recognized in all directions, particularly in the ipsiversive direction. A recovery was observed at 4 wk postlesion for some of these lesion effects. These results suggest that the cerebellar hemispheric region around lobule VII is involved in the control of smooth pursuit and saccadic eye movements.

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