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Abstract:
"Chunking" structures collections of elements and allows
learning and retrieval of information that might otherwise exceed
working memory capacity. The brain mechanisms for chunking
perceptual and motor sequences were studied using event-related
potentials (ERPs). ERPs were recorded using a 128-channel geodesic
sensor array while subjects produced a nine-element motor sequence
previously learned as three "chunks" of three elements. Sequences
were produced in synchrony with stimuli that indicated (a) the
identity and timing of the response, (b) only the timing of the
response, or (c) neither. Response-locked ERPs show motor-potential
differences based on the items' relative positions within a chunk.
Post-response differences were similar when stimuli provide timing
information, while pre-response differences were similar when
response-identity information is absent. Overall the data
illustrate the interaction of chunking with the motor cortices in
the production of a sequence.
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