How Our Brain Responds to Simulated Ego-Motion: Insights from EEG Study

In this study, researchers used high-density electroencephalogram (EEG) to investigate how our brain responds to a simulated sense of self-motion, known as ego-motion. The experiment involved presenting participants with an optic flow stimulus, resembling a road with poles on both sides, which moved forwards and backwards at different speeds, with a static condition in between. The aim was to analyze the brain's electrical activity, focusing on the N2 component of visually evoked potentials and the induced oscillatory activity in the occipital and parietal regions of the cortex. The results revealed that the timing of the N2 peak in specific parietal channels differed between low-speed and high-speed motion conditions. This suggests that our brain processes ego-motion more easily at slower speeds compared to faster speeds. Interestingly, the analysis of N2 peak amplitudes showed larger amplitudes for forward motion compared to backward motion. This indicates that a greater pool of neurons is activated or that there is increased sensitivity specifically for forward motion. The time-frequency analysis further revealed desynchronization in the alpha frequency band in response to all motion conditions. This reflects the brain's processing of visual information or heightened attention and anticipation. In contrast, alpha band synchronizations during the static condition suggest a state of rest or idling. Additionally, a significant desynchronization in the beta frequency band indicated communication between different brain hemispheres. Taken together, these findings suggest that the speed at which we process information related to ego-motion is greatly influenced by our movement velocity through the environment, rather than the direction of the movement itself. Our brain exhibits distinct responses to different aspects of ego-motion, shedding light on how we perceive and navigate the world around us.

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