The electromagnetic activity in the brain prior to reaching movements has been studied extensively in monkeys using direct cell recordings from neurons and in humans using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). The research presented here extends those lines of investigation into human reaching movements using magnetoencephalography (MEG), an advanced electrophysiological tool that allows analysis of higher frequencies than EEG and better temporal resolution than fMRI. Several new findings of signature events in the electromagnetic activity in the brain associated with visuomotor and cognitive components of a reaching movement are reported in this study. The most fascinating is related to target location: an electromagnetic power increase in the beta band (15-25Hz) occurs in the left intraparietal sulcus 2.5 seconds prior to movement for contralateral targets only – not for ipsilateral targets. It is claimed here that this is electrophysiological evidence of a default bias toward reaches to ipsilateral targets, also known as the “proximity-to-hand effect.”
|Advisor:||Simon, Jonathan Z.|
|Commitee:||Hallett, Mark, Hatfield, Bradley, Hodos, William, Lejeuz, Carl|
|School:||University of Maryland, College Park|
|Department:||Neuroscience and Cognitive Science|
|School Location:||United States -- Maryland|
|Source:||DAI-B 71/07, Dissertation Abstracts International|
|Keywords:||Electromagnetic activity, Magnetoencephalography, Movement, Reaching, Spatial fields, Visual targets|
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