Always expect the unexpected: eye position modulates visual cortex excitability in a stimulus-free environment

Area of Science:

• Neuroscience
• Cognitive Science
• Perception

Background:

• Rapid defensive actions are crucial for survival in unpredictable natural environments.
• Previous research indicated motor cortex excitability changes with gaze direction.
• A fundamental neural mechanism may modulate cortical excitability based on gaze location.

Purpose of the Study:

• To investigate if visual cortex excitability is modulated by eye position.
• To test the hypothesis that gaze-dependent cortical excitability extends beyond motor areas.
• To explore the neural basis of monitoring peripheral environments.

Main Methods:

• Applied single-pulse transcranial magnetic stimulation (TMS) to the right lateral occipital lobe.
• Participants directed their eyes to the left, straight-ahead, or to the right.
• Recorded phosphene perception to assess visual cortex excitability.

Main Results:

• Visual cortex excitability was significantly greater when eyes were deviated to the right compared to the left.
• Phosphene elicitation varied with eye position, indicating gaze-dependent modulation.
• This finding complements previous motor cortex excitability changes related to gaze alignment.

Conclusions:

• Eye position directly modulates visual cortex excitability.
• This mechanism likely facilitates the detection of stimuli in non-foveated space.
• The findings support the concept of 'surveillance attention' for monitoring peripheral environments.