Visual adaptation stronger at horizontal than vertical meridian: Linking performance with V1 cortical surface area

Area of Science:

• Neuroscience
• Visual Perception
• Computational Neuroscience

Background:

• Visual performance exhibits systematic variations with polar angle, including horizontal-vertical anisotropy (HVA) and vertical meridian asymmetry (VMA).
• These visual field asymmetries are known to be robust against attentional modulation.
• The influence of visual adaptation on these polar-angle-dependent asymmetries remains largely unexplored.

Purpose of the Study:

• To investigate how visual adaptation affects contrast sensitivity at different visual field locations (fovea and perifovea).
• To examine adaptation effects across the four cardinal meridians for both horizontal and vertical stimulus orientations.
• To determine if adaptation influences established visual field asymmetries like HVA.

Main Methods:

• Contrast sensitivity was measured in human adults under non-adapted and adapted conditions.
• Adaptation involved exposure to repetitive stimuli at the fovea and perifovea across horizontal and vertical meridians.
• Orientation discrimination tasks were used to assess performance.
• Correlation analysis was performed between adaptation effects and V1 cortical surface area.

Main Results:

• The horizontal-vertical anisotropy (HVA) was more pronounced for horizontal stimuli compared to vertical stimuli in non-adapted conditions.
• Visual adaptation was stronger along the horizontal meridian than the vertical meridian for both stimulus orientations.
• Adaptation effects at the perifovea were found to positively correlate with the individual's V1 cortical surface area.

Conclusions:

• Visual adaptation plays a significant role in modulating contrast sensitivity across the visual field.
• Adaptation serves to mitigate the horizontal-vertical anisotropy (HVA), promoting more uniform visual perception.
• These findings suggest that visual adaptation contributes to bioenergetic efficiency by reducing sensitivity to redundant stimuli and normalizing visual field performance.