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Abstract:
Awake temporal lobe epilepsy patients undergoing neurosurgery
present a unique opportunity for the study of neuronal activity
during cognitive tasks. Extracellular microelectrodes recorded 113
neurons in 25 patients (13 in dominant hemisphere) while the
patients engaged in memory tasks using auditory words, text, and
visual objects. Using a Brown-Peterson paradigm, we assessed recent
distracted and non-distracted working memory after nine seconds.
Each trial included an acquisition item, a period of time where the
memory must be stored (with or without an intervening task) and a
cue for retrieval by overt recall. For the distracted trials, three
unrelated items were presented between an acquisition item and the
cue for overt recall. For the non-distracted trials, a screen with
a blinking asterisk was presented between the acquisition item and
the cue for overt recall. Analysis of neural activity during the
recalled items under these two conditions permits assessment of
changes related to the distraction task. We observed significant
changes (p < .00625) in 25% (29/113) of the neurons related to
the added demands of distraction. These changes were not specific
to a presentation modality and were present across the duration of
the recording epoch. These results may reflect the influence of a
thalamo-cortical attentional system during memory recall. Supported
by NIH grant NS 35627 and Pew-McDonnell Foundation
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