Comparative study of event-related potentials and positron emission tomography activation during a paired-associate memory paradigm |
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Authors: | M Honda Geoff Barrett Nahoko Yoshimura Norihiro Sadato Yoshiharu Yonekura Hiroshi Shibasaki |
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Institution: | (1) Department of Brain Pathophysiology, Kyoto University School of Medicine, Shogoin, Sakyo-ku, Kyoto, 606–01 Japan Fax: +81–75–751–3202, e-mail: mhonda@kuhp.kyoto-u.ac.jp, JP;(2) Defence Research Agency, Alverstoke, Hants, UK, GB;(3) Biomedical Imaging Research Center, Fukui Medical School, Fukui, Japan, JP |
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Abstract: | Event-related potentials (ERP) and regional cerebral blood flow (rCBF) activation using 15O-labeled water associated with retrieval and retention of episodic memory were studied during a visual paired-association
task with delayed response in eight healthy subjects. In both studies, the subjects memorized four pairs of figures during
the learning period. They were presented with each cue (S1) and asked to judge whether the following figure (S2) formed one
of the memorized pairs. In an attempt to identify brain activity related to memory function, a choice reaction task with delay
was used as a behavioral control. The ERP study showed a posterior positive component in the difference waveform, which was
obtained by subtracting responses in the choice reaction task from those in the paired association task, between 300 and 850
ms after S1 presentation. It was maximal at the parietal midline electrode and distributed predominantly over the left posterior
quadrant of the scalp. The rCBF activation study showed a greater increase in rCBF in the right dorsolateral prefrontal cortex
(Brodmann’s area 46), left inferior frontal cortex (Brodmann’s area 44/45), left thalamus, and bilateral cerebellar hemisphere
during the paired association task as compared to the choice reaction task, which suggests a possible involvement of cerebello-thalamo-cortical
circuit in the memory processing. Additionally, it is suggested that the scalp distribution of the ERP component may not necessarily
represent regional cortical activation below the electrodes where such a component is observed and could indirectly represent
activation in remote areas such as subcortical regions. It seems that ERP and rCBF activation may provide information about
different aspects of higher brain function.
Received: 19 July 1996 / Accepted: 22 August 1997 |
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Keywords: | Event-related potentials PET Paired association task Working memory Episodic memory Human |
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