Visual field maps, population receptive field sizes, and visual field coverage in the human MT+ complex

Area of Science:

• Neuroscience
• Visual Perception
• Neuroimaging

Background:

• Human neuroimaging traditionally uses stationary vs. moving stimuli to find motion-selective cortex (MT+).
• MT+ is located at the temporal-occipital (TO) boundary and suspected to contain multiple visual field maps.
• Previous studies have only mapped one coarse visual field representation within MT+.

Purpose of the Study:

• To identify and characterize distinct visual field maps within human motion-sensitive cortex (MT+).
• To measure population receptive field (pRF) sizes and visual field coverage of these newly identified maps.

Main Methods:

• Utilized a novel functional Magnetic Resonance Imaging (fMRI) model-based method.
• Identified two distinct visual field maps, TO-1 and TO-2, at the temporal-occipital (TO) boundary.
• Measured population receptive field (pRF) sizes and analyzed angular and eccentricity representations.

Main Results:

• Discovered two new visual field maps, TO-1 and TO-2, within human MT+.
• TO-1 and TO-2 exhibit unique angular representations and a parallel eccentricity map (ventral-to-dorsal).
• pRF size progressively increases from early visual areas to TO-1/2, with largest pRFs in TO-2; pRF size also increases with eccentricity within each map.
• Both maps extend into the ipsilateral visual field, with TO-2 showing greater sensitivity to peripheral ipsilateral stimuli.

Conclusions:

• The identified TO-1 and TO-2 maps provide a functional segmentation of human motion-sensitive cortex.
• This segmentation enables a more detailed characterization of visual processing within MT+.
• The findings advance our understanding of the organization and function of human motion perception areas.