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Program#/Poster#: 667.1
Title:
Subsequent memory dependent EEG theta correlates with hippocampal BOLD response inhuman Location:
Presentation
Start/End Time:
Authors:
*N. SATO1, T. OZAKI1, Y. SOMEYA2, K. ANAMI2, S. OGAWA2, H. MIZUHARA1,3, Y.
YAMAGUCHI1;
1Lab.Dynamics Emergent Intelligence, RIKEN Brain Sci. Inst., Wako-shi, Japan; 2Ogawa Lab.
Brain Function Res., Hamano Life Sci. Res. Fndn., Tokyo, Japan; 3Dep of Intelligence Sci. and
Tech. Grad Sch. of Informatics, Kyoto Univ., Kyoto, Japan
Patient studies of the hippocampal damage clearly demonstrated that the hippocampus is associated with object-
place associative memory. It suggests the importance of the hippocampus in storing multiple information contents in
the environment, while its neural mechanism is an open question. The authors have proposed a cortico-hippocampal
network model of the memory task (Sato and Yamaguchi, Hippocampus 2005). In this model, a hippocampal neural
dynamics, "theta phase precession", observed in rat hippocampus was applied to cortico-hippocampal system with a
randomly saccadic visual input sequence. The computational experiments demonstrated that theta phase precession
contributes to the formation of multiple object-place memories in the CA3 network consisting of spatial scale-related
asymmetric connections among object and scene units. Human scalp EEG study (Sato and Yamaguchi,
NeuroReport, 2007) demonstrated that EEG theta power and coherence during encoding increase in relation to the
subsequently successful recall, while it remains unclear whether the hippocampus is associated with such a scalp
EEG theta or not.
In this paper, we directly evaluated the relation between the scalp EEG theta and the hippocampal activity by using a
simultaneous EEG-functional magnetic resonance imaging (fMRI) recording. Eight participants completed an object-
place memory task consisting of a 10-sec encoding of four object-place associations and a recall with an 18-sec
delay. BOLD signals were acquired with a 3-T Siemens Allegra MRI scanner during performing the task and 64-ch
scalp EEG were simultaneously recorded. In the fMRI data analysis, hippocampal region of interest (ROIs) were
individually defined and used for the subsequent memory analysis for successful and failed trials.
In the result, by removing large artifacts, we successfully detected the EEG theta power increase in relation to the
subsequently successful recall. Moreover a cross-correlation analysis demonstrates that the EEG theta power at the
central region is significantly correlated to the hippocampal blood oxygenation level dependent (BOLD) response. In
conclusion, these results support the hypotheses that hippocampal theta dynamics, as observed in the rat
hippocampus, facilitates the memory encoding of what and where in human episodic memory.
Disclosures:
N. Sato , None; T. Ozaki, None; Y. Someya, None; K. Anami, None; S. Ogawa, None; H.
Mizuhara, None; Y. Yamaguchi, None.
[Authors]. [Abstract Title]. Program No. XXX.XX. 2007 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2007. Online.
2007 Copyright by the Society for Neuroscience all rights reserved. Permission to republish any abstract or part of any abstract in any form must be obtained in writing by SfN office prior to OASIS - Online Abstract Submission and Invitation System™ 1996-2007, Coe-Truman Technologies, Inc.
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Source: http://www.fun.ac.jp/~satonao/paper/sato-07sfn.pdf