TY - JOUR
T1 - Successful verbal encoding into episodic memory engages the posterior hippocampus
T2 - A parametrically analyzed functional magnetic resonance imaging study
AU - Fernández, Guillén
AU - Weyerts, Helga
AU - Schrader-Bölsche, Michael
AU - Tendolkar, Indira
AU - Smid, Henderikus G O M
AU - Tempelmann, Claus
AU - Hinrichs, Hermann
AU - Scheich, Henning
AU - Elger, Christian E.
AU - Mangun, George R
AU - Heinze, Hans Jochen
PY - 1998/3/1
Y1 - 1998/3/1
N2 - The medial temporal lobe (MTL) is essential for episodic memory encoding, as evidenced by memory deficits in patients with MTL damage. However, previous functional neuroimaging studies have either failed to show MTL activation during encoding or they did not differentiate between two MTL related processes: novelty assessment and episodic memory encoding. Furthermore, there is evidence that the MTL can be subdivided into subcomponents serving different memory processes, but the extent of this functional subdivision remains unknown. The aim of the present functional magnetic resonance imaging (fMRI) study was to investigate the role of the MTL in episodic encoding and to determine whether this function might be restricted to anatomical subdivisions of the MTL. Thirteen healthy volunteers performed a word list learning paradigm with free recall after distraction. Functional images acquired during encoding were analyzed separately for each participant by a voxel-wise correlation (Kendall's tau) between the time series of the T2*- signal intensity and the number of subsequently recalled words encoded during each particular scan. Of the 13 participants, 11 showed voxel clusters with statistically significant, positive correlations in the posterior part of the hippocampus. Across participants, an ANOVA on the number of voxels with significant, positive correlations within individually defined volumes of interest confirmed a statistically significant difference in activation for anterior versus posterior regions of the hippocampus. However, no differences between left and right hippocampal activation were revealed. Thus, these findings demonstrate that successful encoding into episodic memory engages neural circuits in the posterior part of the hippocampus.
AB - The medial temporal lobe (MTL) is essential for episodic memory encoding, as evidenced by memory deficits in patients with MTL damage. However, previous functional neuroimaging studies have either failed to show MTL activation during encoding or they did not differentiate between two MTL related processes: novelty assessment and episodic memory encoding. Furthermore, there is evidence that the MTL can be subdivided into subcomponents serving different memory processes, but the extent of this functional subdivision remains unknown. The aim of the present functional magnetic resonance imaging (fMRI) study was to investigate the role of the MTL in episodic encoding and to determine whether this function might be restricted to anatomical subdivisions of the MTL. Thirteen healthy volunteers performed a word list learning paradigm with free recall after distraction. Functional images acquired during encoding were analyzed separately for each participant by a voxel-wise correlation (Kendall's tau) between the time series of the T2*- signal intensity and the number of subsequently recalled words encoded during each particular scan. Of the 13 participants, 11 showed voxel clusters with statistically significant, positive correlations in the posterior part of the hippocampus. Across participants, an ANOVA on the number of voxels with significant, positive correlations within individually defined volumes of interest confirmed a statistically significant difference in activation for anterior versus posterior regions of the hippocampus. However, no differences between left and right hippocampal activation were revealed. Thus, these findings demonstrate that successful encoding into episodic memory engages neural circuits in the posterior part of the hippocampus.
KW - Alzheimer's disease
KW - Declarative memory
KW - Encoding
KW - Episodic memory
KW - fMRI
KW - Functional neuroimaging
KW - Hippocampus
KW - Medial temporal lobe
KW - Memory formation
KW - Parametrical analysis
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M3 - Article
C2 - 9465008
AN - SCOPUS:2542508993
VL - 18
SP - 1841
EP - 1847
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 5
ER -