Visual sensitivity and bias oscillate phase-locked to saccadic eye movements

Area of Science:

• Neuroscience
• Visual Perception
• Cognitive Science

Background:

• Perceptual performance exhibits oscillations linked to voluntary actions like eye movements.
• Suprathreshold contrast discrimination accuracy shows delta-range (2-3 Hz) oscillations phase-locked to saccadic eye movements.
• Saccadic suppression is integrated within these perceptual oscillations.

Purpose of the Study:

• To investigate whether rhythmic modulations influence absolute detection thresholds, not just suprathreshold appearance.
• To measure location discrimination of brief Gabor patches around voluntary saccades.
• To determine the frequency and phase-locking of oscillations in absolute contrast thresholds and response bias.

Main Methods:

• Measured location discrimination of Gabor patches presented before and after voluntary saccades.
• Analyzed oscillations in absolute contrast thresholds and response bias.
• Compared oscillation frequencies and phase-locking with saccadic onset.

Main Results:

• Absolute contrast thresholds oscillated at a delta frequency (2-3 Hz), similar to suprathreshold discrimination.
• Saccadic suppression was phase-locked with absolute threshold oscillations.
• Response bias also oscillated, but in the alpha range, distinct from sensitivity oscillations.
• Demonstrated perisaccadic delta oscillations in visual sensitivity, independent of alpha-range bias oscillations.

Conclusions:

• Visual sensitivity exhibits perisaccadic delta oscillations phase-locked to saccadic eye movements.
• These oscillations are independent of response bias oscillations, which occur in the alpha range.
• The findings support a significant role for oscillations in timing the relationship between eye movements and visual processing.