Increasing interhemispheric connectivity between human visual motion areas uncovers asymmetric sensitivity to...

Area of Science:

• Neuroscience
• Cognitive Science
• Visual Perception

Background:

• Conscious perception involves hierarchical processing and sensory integration.
• Information integration between brain hemispheres may follow similar hierarchical principles.
• The visual motion complex (V5/MT+) processes horizontal motion perception.

Purpose of the Study:

• To investigate the role of interhemispheric connectivity in visual motion perception.
• To test if hierarchical processing scales to interhemispheric integration in the visual cortex.
• To examine the influence of manipulating V5/MT+ connectivity on motion perception.

Main Methods:

• Used transcranial magnetic stimulation (TMS) to manipulate connectivity between left and right V5/MT+ areas.
• Induced spike-timing-dependent plasticity to strengthen specific interhemispheric pathways.
• Measured changes in sensitivity and perceptual bias for horizontal motion stimuli.

Main Results:

• Enhancing left-to-right V5/MT+ connections increased horizontal motion sensitivity.
• This effect was immediate and lasted over 90 minutes.
• Strengthening right-to-left connections had minimal perceptual impact, but could reverse a leftward motion bias.
• Observed an inherent leftward bias in motion perception that could be modulated by interhemispheric strengthening.

Conclusions:

• Human visual cortex exhibits asymmetric projections between left and right V5/MT+.
• These asymmetric connections play a hierarchical role in hemispheric specialization.
• Left-to-right processing is favored for integrating local visual input into global motion perception.