TIME COURSE AND VISUAL PRESENTATION EFFECTS ON THE MOTOR MIRROR NEURON SYSTEM INDUCED BY TRANSCRANIAL MAGNETIC STIMULATION

Abstract

The study of mirror neurons (MN) has a long way since its discovery on monkeys and later on humans. However, there are inconsistencies on the way that stimuli are presented and on the time of stimuli presentation. Which is the optimal way to present motor movement stimuli? Is it possible to estimate the time course of the mirror neurons effect by using transcranial magnetic stimulation at specific time windows? In the current study we investigated different type of stimuli presentation (photo and video of hand movements) by using single pulse Transcranial Magnetic Stimulation of the dominant primary motor cortex (M1) at different time windows (0, 320, 640 ms). Motor evoked potentials from FDI (index finger muscle) and ADM (little finger muscle) were recorded on 11 healthy subjects at rest with their hands in orthogonal position while only observing the visual stimuli in three different presentation conditions. Our results showed that Video presentation induces the strongest mirror effect at 320 ms from the movement onset. This effect is muscle specific. The current evidence provides an optimal protocol for the investigation of the mirror neurons system in humans and pave the way for future clinical application and rehabilitation.