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Sensorimotor Control

開催日 2014/9/12
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Temporal changes of brain wave during switches in motor imagery

  • P2-120
  • 横山 寛 / Hiroshi Yokoyama:1 南部 功夫 / Isao Nambu:1 井澤 淳 / Jun Izawa:2 和田 安弘 / Yasuhiro Wada:1 
  • 1:長岡技術科学大学 / Nagaoka Univ of Technology, Japan 2:NTTコミュニケーション科学基礎研 / NTT CS Labs, Japan 

Motor imagery refers to imagining one's own motor movements without any motor execution, and has been used in studies as powerful tool for rehabilitation with stroke patients. It has been studied as an effective strategy to recover patient's motor dysfunction because simply imagining motion of their limbs can engage their brains' intact sensory-motor systems. For instance, if there is a training program that consists of switching their imagined actions, it might help patient to recover poor ability of motor switching as Parkinson's disease. However, despite its importance little is known about exact process of mental images of one's switching action in the brain. A study using functional magnetic resonance imaging (fMRI) with Parkinson's disease patients is suggesting a possible role in motor switching. Nevertheless, the fMRI with its poor temporal resolution is not a recommended technique to study switching motor imagery because action switching is performed continuously within a very short time period. Then, we set out to clarify this issue by measuring brain activity reflected in electroencephalograms (EEGs) as subjects switched an imagined hand rotation from one hand to the other during a motor imagery task. Participants performed the hand laterality judgment task that involves action selection. Mainly, to suggest temporal changes of switch related brain wave, we focus on event-related desynchronization (ERD) and rotation-related negativity (RRN) during task because these are reflected the internal state of brain to simulate imaging them actions. By comparing the EEG signals from repeated mental imaging of hand movements, we found a switch-specific ERD in the beta-band activity in parietal and frontal regions around 0.6-0.7 s after stimulus presentation. Further, we found RRN in the parietal cortex at the same time as the decreased beta-band power. These results suggest that the parietal area is dynamically involved in the switching of imagined hand motion, and that frontal areas may have an important role in inhibiting mental imagery of the deselected hand's motion. Alternatively, these results also suggest that we may be able to facilitate their ability to switch between real motor tasks by providing online biofeedback of these signals to patients.

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