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Abstract:
The hypothesis of a functional equivalence between
preparation to motor execution (PE) and preparation to motor
imagery (PI), and between motor execution (ME) and motor imagery
(MI) was investigated by using multichannel EEG. Ten right-handed
subjects had to execute/imagine a sequence of externally paced
finger movements. Topographic event-related potential (ERP) maps
were analyzed using techniques associating ERP map configurations
of different time periods with functional states of the brain.
Additionally, the contingent negative variation (CNV) elicited in
the preparation period (interval between the preparatory stimulus
specifying the mode of response and the first go signal) was
studied. Concerning the preparation period, the facts that 1)
similar maps were found for PE and PI, and 2) CNV amplitude and
global intensity of the scalp topography were larger for PE than
for PI, suggest that the difference between PE and PI is
quantitative rather than qualitative. Concerning the mode of
response, a map corresponding to motor activation was identified,
occurring at similar latency in both ME and MI. This observation
confirms the implication of similar neural substrates for the two
types of responses and strongly suggests that primary motor
structures are involved not only in ME but also in MI.
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