Magnetoencephalogram recording from secondary motor areas during imagined movements

Abstract

-This study determined whether the activity of the secondary motor cortex (M2) could be re c o rded during imagined movements (IM) of the right and left hand using magnetoencephalography (MEG). Results during IM were compared with a somatosensory trial during a passive tactile stimulation in one subject. During the somatosensory trial, dipoles were detected in somatosensory (SS) and motor primary (M1) areas, scoring 94.4-98.4% for SS, 1.6-5.6% for M1 and 0% for M2. During the IM trial, dipoles were detected in SS, M1 and M2 areas, scoring 61.1-68.8% for SS, 2.6-9.3% for M1 and 28.6-29.6% for M2. These data support the hypothesis that M2 areas are activated during imagined hand movements. This study aims for the development of a diagnosis test for patients with motor deficits by evaluating the whole somatomotor network with specific interest in M2 areas.KEY WORDS: secondary motor cortex, somatosensory areas, motor primary areas, magnetoencephalography (MEG), motor imagined movements. Registro magnetoencefalográfico de áreas motoras secundárias durante simulação interna do movimentoRESUMO -Este estudo determina se a atividade motora secundária cortical (M2) pode ser gravada durante simulação interna do movimento (IM) das mãos direita e esquerda utilizando-se magnetencefalografia (MEG). Os resultados da simulação dos movimentos estudados foram comparados com um ensaio somato-sensorial com estimulação tactil passiva em um sujeito. Durante o ensaio somato-sensorial dipolos foram detectados em áreas somato-sensoriais (SS) e motoras primarias (MI) tendo como score 94,4-98,4% para SS, 1,6-5,6% para M1 e 0% para M2. Durante o ensaio de simulação dos movimentos também foram detectados dipolos em SS 61,1-68,8%, M1 2,6-9,3% e M2 28,6-29,6%. Estes dados evidenciam a hipótese de que as áreas M2 são ativadas durante a simulação dos movimentos das mãos. Este estudo sugere o desenvolvimento de um teste diagnóstico para pacientes com deficites motores, que avalie a rede somatomotora com interesse específico nas áreas M2.PA L AV R A S -C H AVE: áreas motoras secundárias, áreas somato-sensoriais, áreas motoras, magnetencefalografia (MEG), simulação interna do movimento.Motor Imagery or Imagined Movements (IM) have been defined as conscious mental rehearsal of a motor act without perf o rming any overt movement and implies that the subject feels himself executing a given action 1 . Execution and internal simulation of movements seem to follow the same temporal characteristics and use the same neural re p re s e n t a t i o n s 2 . S t udies using diff e rent neuroimaging techniques to characterize IM have revealed activation of a number of cortical motor areas [3][4][5][6] shown also by Magnetoencephalograpy (MEG) 7 , 8 . MEG provides high spatial and temporal re s o l u t i o n 9 allowing characterizing with precision the temporal sequence of different motor a reas activated during IM. Based on a previous MEG p rotocol to evaluate motor and somatosensory function simultaneously 1 0 , the aim of the present study is to det...

Induced gamma band activity from EEG as a possible index of training-related brain plasticity in motor tasks

“…In previous experiments with magnetoencephalography (MEG), it has been verified that the same motor task used in this study, causes activation of the motor cortical network (primary and supplementary motor areas) with both voluntary and imagined movement [ 14 , 15 ].…”