Event-Related Desynchronization of Spontaneous Rhythm Caused by Anticipation of Collision

Abstract

Event Abstract Back to Event Event-Related Desynchronization of Spontaneous Rhythm Caused by Anticipation of Collision Gakuto Aoyama1*, Koichi Yokosawa1, Shinya Kuriki2 and Makoto Takahashi1 1 Hokkaido University, Japan 2 Tokyo Denki University, Japan Animals, including human beings, subconsciously evade collisions. We have been investigating endogenous brain activity by MEG when humans anticipate a collision or intend to take evasive action. A form that expands rapidly while maintaining shape is recognized as a collision [1]. We presented participants with a collision-simulating image with a prior cue signal. Here we report results showing how spontaneous brain activity is modified by anticipation of a collision. MEG signals were recorded with a 76-ch helmet system (Elekta-Neuromag, custom-type) from 11 healthy male volunteers (24.9±3.9 years old). Each participant was presented with a visual collision-simulating stimulus in which a black indeterminate form expanded on a grey background in 170 ms (A: collision stimulus). As controls, two kinds of stimuli were presented. One was a uniform background, the brightness of which decreased with time to darkness (B: darkening stimulus), and the other was the black indeterminate form that changed in size in a random manner (C: random stimulus). A cue stimulus was given visually two seconds before each (A, B, or C) stimulus to enable the participant to anticipate the coming stimulus. One experimental session included 120 epochs per stimulus, in random order. Amplitude of spontaneous alpha band (8-13 Hz) rhythm decreased just after the onset of each stimulus and increased dramatically 400 ms later. The most notable result was that the amplitude of alpha rhythm before the collision stimulus (A) was significantly smaller than that before each control stimulus (B or C) (p<0.05) during the period between cue and stimulus. This result suggests that spontaneous brain activity in the alpha band is reduced by anticipating a negative (dangerous) event, possibly to prepare evasive action.