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Abstract:
Abstract: We explored whether semantic processes were
actively engaged in the short-term maintenance of verbal
information by examining how semantic properties of sentences to be
remembered affect brain activation patterns during retention.
Event-related potentials (ERPs) at 24 scalp locations were recorded
from 16 right-handed women during the visual presentation of
sentences and a following 2500ms delay interval. After the delay,
subjects had to decide whether a statement about the sentence was
true. We manipulated the difficulty of integrating sentence meaning
by using two sentence structures, filler-gap (difficult
integration) and non-filler-gap (easy integration), and two levels
of semantic relatedness among words in the sentence (high/low).
Subjects' error rates were higher when integrating sentence meaning
was difficult (p<.00007), or semantic relatedness was low
(p<.003). Filler-gap sentences with low semantic relatedness
produced the highest error rates (p<.023) compared to other
sentence types. The effects upon ERPs during retention of semantic
relatedness and sentence structure interacted in an analogous way
(p<.021). There was a large positive slow wave over left
parieto-temporal scalp during retention of filler-gap sentences
with low semantic relatedness, but not other sentence types. The
ERP data indicate that semantic processes dependent upon the
relatedness of words in sentences and ease of integrating sentence
meaning were actively engaged during short-term verbal working
memory processing.
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