Pre-microsaccadic Modulation in Foveal V1: Enhancement in the Current and Future Stimulus Locations

Area of Science:

• Neuroscience
• Visual Perception
• Ophthalmology

Background:

• Microsaccades, miniature saccades during visual fixation, are crucial for active sensing.
• Pre-microsaccadic attention is hypothesized to enhance visual processing, but the underlying neural mechanisms at the foveal scale are unclear.

Purpose of the Study:

• To investigate the neuronal mechanisms of spontaneous microsaccades in the foveal primary visual cortex (V1).
• To determine if neural activity is modulated prior to microsaccades, particularly in relation to visual stimulus location.

Main Methods:

• Utilized voltage-sensitive dye imaging in behaving macaque monkeys.
• Recorded neural responses in V1 during spontaneous, uninstructed microsaccades.
• Analyzed neural activity relative to the direction of microsaccades concerning a small visual stimulus.

Main Results:

• Found enhanced neuronal activity at current and future microsaccade landing sites preceding movements toward a stimulus.
• This enhancement was spatially restricted to the microsaccade trajectory (<1 degree) in V1.
• Observed increased neuronal synchronization at the current stimulus site before microsaccade onset.

Conclusions:

• Neural activity is modulated in anticipation of microsaccades, specifically enhancing processing at upcoming fixation points.
• Findings suggest a link between pre-microsaccadic neural modulations and attentional mechanisms.
• Provides insights into the neural basis of active sensing and visual attention at the foveal level.