P79-T Sensory-motor integration during a visuomotor sequence learning task

Abstract

Background Sensory-motor integration (SMI) is an important process in the learning and execution of voluntary movements. This study aimed to test the electrophysiological course of SMI along with fMRI during visuomotor sequence learning (VMSL). Methods Nineteen healthy participants were included. They performed the VMSL task with their left hand. On the first day, they completed one training run and a test run. They repeated daily training tasks and were re-tested on the fifth day. Ipsilateral electrical median nerve stimulation followed by transcranial magnetic stimulation of the contralateral motor cortex with various interstimulus intervals (ISI) were performed. Recordings were made from left forearm flexor and extensor muscles. SMI studies were performed at before (T0) and after (T1) 1st-day training, and after 5th-day training (T2). Motor response (MEP) ratios for each ISI were calculated. Mean reaction time (RT) and mean error rate were measured. Results RTs (training: 283.37 ± 65.76; test: 235.20 ± 51.00; re-test: 194.26 ± 50.26 ms) and mean error rates (0.19 ± 0.16; 0.06 ± 0.06; 0.02 ± 0.03, respectively) improved significantly in the early and late stages. MEP ratios showed early afferent inhibition (SAI, ISIs 20–35 ms), late afferent inhibition (LAI, ISIs 80–200 ms) and intervening afferent facilitation (AF) for forearm flexors. Although MEP ratios at T0 andT1 were very similar, less SAI and more AF were observed at T2. Conclusions There was a tendency for decreased SAI and increased AF towards the end of the learning period. This may be caused by the learning task which requires a more prominent sensorimotor integration towards the end of the study.