Prehension and perception of size in left visual neglect

Area of Science:

• Neuroscience
• Cognitive Psychology
• Rehabilitation Science

Background:

• Right hemisphere damage can lead to visuospatial deficits, including left visual neglect.
• Understanding visual size processing in neglect is crucial for rehabilitation and daily functioning.
• Previous research has yielded mixed results on size perception deficits in neglect patients.

Purpose of the Study:

• To investigate visual size processing in patients with right hemisphere damage, with and without left visual neglect.
• To assess size perception in both perceptual-experiential (estimation) and action-based (grasping) contexts.
• To explore potential movement abnormalities associated with size processing in these patient groups.

Main Methods:

• Participants included patients with right hemisphere damage (with/without left visual neglect) and age-matched controls.
• Objects of varying sizes were presented in the left or right body hemispace.
• Tasks involved size estimation and reaching to grasp objects.

Main Results:

• No impairments in size processing were found during the prehension (grasping) performance of neglect patients.
• A generalized slowing of movement and an extended deceleration phase were observed in both patient groups.
• Both patient groups reached maximum grip aperture later in the movement compared to controls.

Conclusions:

• Right hemisphere damage, even with left visual neglect, does not necessarily impair visual size processing for action or perception.
• Movement execution, particularly deceleration and grip adjustments, is affected in these patients.
• The expected underestimation of object sizes in left hemispace for neglect patients was not observed, suggesting preserved size perception.