Poster B117, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Sensorimotor Synchronization at 3 Tempi
GEORGIOS MICHALAREAS1,3, Francesco Di Pompeo2, Pascal Fries3, David Poeppel1,4; 1Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, 2Institute for Advanced Biomedical Technologies, University G. D’Annunzio, 3Ernst Strüngmann Institute for Neuroscience in Cooperation with Max Planck Society, 4Department of Psychology, New York University
We present evidence for the concurrence of three Sensorimotor Synchronization (SMS) models in the human brain, each with distinct temporal dynamics. Participants were presented with blocks of 10 flashes, with a fixed inter-flash interval (IFI = 1.2 sec), and were instructed to flex one of four extremities (either hand or foot) in synchrony with the flashes. In all trials within any given block, the same extremity was used and blocks were presented in a pseudo-random sequence. (Data from the Human Connectome Project.) The main behavioral metric is the time asynchrony between the muscle movement (EMG) onset and the corresponding instructing visual stimulus, termed here “VMA (Visuo-Motor Asynchrony)”. The analyses reveal three main phenomena: 1) Movement onset for feet was on average ~50 msec earlier than hands, consistently across the experiment. 2) Within each block, VMA followed a U-shaped pattern. Additionally, the within-block VMA variance, contrary to expectation, increased in the first third of the experiment and then stabilized. 3) The mean VMA across blocks follows a slow but consistent negative drift from positive values (movement onset after flash) towards negative values (movement onset before flash). The slope of the drift appears to be similar in each extremity and most importantly is extremity specific, hinting at the existence of sensorimotor memory specific to each extremity. These three findings suggest three largely independent models in the human brain regarding sensorimotor synchronization. We probe the relevant brain networks with magnetoencephalography data.
Topic Area: PERCEPTION & ACTION: Motor control