Rythmic modulation of V1 BOLD response (7T) after a Voluntary action

Abstract

To interact effectively with the external world, motor and visual processing need to be tightly synchronized in time. One possible synchronization mechanism may be phase resetting of endogenous rhythms of motor and visual cortex. In previous studies we have shown that voluntary actions can induce long-lasting rhythmic (5–7 Hz) oscillations in visual contrast sensitivity, even for stimuli irrelevant to that action. Here we demonstrate that BOLD responses of early stages of visual processing are rhythmically modulated in synchrony with a voluntary action, with ultra-high field MRI (7T) measurements during a 2AFC task. Participants discriminated the spatial frequency of two brief (33 ms) gratings of 1.0 and 1.1 c/deg, presented randomly in the upper or lower visual field: participants initiated each trial in the scanner by a button press, at will. The stimulus was displayed randomly with either 70 ms or 150 ms delay, corresponding to the minima and the maxima of the first oscillation in visual discrimination sensitivity, and subjects responded after a delay (>20s). Results from 10 participants indicate that visual stimuli presented at 150 ms delay (oscillation peak) elicited stronger responses than those presented at 70 ms delay (oscillation trough), for all stimulated eccentricities. However, the button press alone (without visual stimulation) elicited no response in V1, at any retinotopic eccentricity. The modulation of BOLD responses occurred at all early visual areas, including V1, V2, V3 and V4, and was consistent with the behavioral performance measured outside the scanner for the same task. These results suggest an early visuo-motor interaction, at the level of V1. The rhythmic modulation points to synchronization of vision and action that shapes vision by alternatively suppressing and enhancing processing.

Acknowledgement: ERC grant ESCPLANE