Hemisphere-dependent attentional modulation of human parietal visual field representations

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• The posterior parietal cortex (PPC) features topographic maps of the contralateral visual field.
• Research indicates potential hemispheric differences in PPC responses to ipsilateral stimuli, influenced by task demands.

Purpose of the Study:

• To investigate how spatial attention affects the population receptive field (pRF) characteristics within human topographic parietal cortex.
• To determine the impact of attention on both the size and preferred location of pRFs in each hemisphere.

Main Methods:

• Utilized a two-dimensional Gaussian model to characterize the pRF for each voxel in the topographic parietal cortex.
• Measured changes in pRF center (preferred location) and size (visual field extent) under different attentional conditions.

Main Results:

• Attending to a stimulus, compared to fixation, enlarged pRFs in both hemispheres.
• In the left hemisphere, attention shifted preferred locations towards more peripheral contralateral representations, preserving contralateral mapping.
• In the right hemisphere, attention modulated pRF size but not preferred location, significantly increasing representation of the ipsilateral visual hemifield.

Conclusions:

• Attentional modulation of pRFs in topographic parietal cortex demonstrates hemispheric asymmetries.
• These asymmetries mirror those observed in hemispatial neglect, suggesting potential neural mechanisms for the disorder.