Remote Effects of Hippocampal Sclerosis on Effective Connectivity during Working Memory Encoding: A Case of Connectional Diaschisis?

Campo, Pablo, Garrido, Marta I., Moran, Rosalyn J., Maestu, Fernando, Garcia-Morales, Irene, Gil-Nagel, Antonio, del Pozo, Francisco, Dolan, Raymond J. and Friston, Karl J. (2012) Remote Effects of Hippocampal Sclerosis on Effective Connectivity during Working Memory Encoding: A Case of Connectional Diaschisis?. Cerebral Cortex, 22 6: 1225-1236. doi:10.1093/cercor/bhr201


Author Campo, Pablo
Garrido, Marta I.
Moran, Rosalyn J.
Maestu, Fernando
Garcia-Morales, Irene
Gil-Nagel, Antonio
del Pozo, Francisco
Dolan, Raymond J.
Friston, Karl J.
Title Remote Effects of Hippocampal Sclerosis on Effective Connectivity during Working Memory Encoding: A Case of Connectional Diaschisis?
Journal name Cerebral Cortex   Check publisher's open access policy
ISSN 1047-3211
1460-2199
Publication date 2012-06
Year available 2012
Sub-type Article (original research)
DOI 10.1093/cercor/bhr201
Open Access Status
Volume 22
Issue 6
Start page 1225
End page 1236
Total pages 12
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Collection year 2012
Language eng
Formatted abstract
Accumulating evidence suggests a role for the medial temporal lobe (MTL) in working memory (WM). However, little is known concerning its functional interactions with other cortical regions in the distributed neural network subserving WM. To reveal these, we availed of subjects with MTL damage and characterized changes in effective connectivity while subjects engaged in WM task. Specifically, we compared dynamic causal models, extracted from magnetoencephalographic recordings during verbal WM encoding, in temporal lobe epilepsy patients (with left hippocampal sclerosis) and controls. Bayesian model comparison indicated that the best model (across subjects) evidenced bilateral, forward, and backward connections, coupling inferior temporal cortex (ITC), inferior frontal cortex (IFC), and MTL. MTL damage weakened backward connections from left MTL to left ITC, a decrease accompanied by strengthening of (bidirectional) connections between IFC and MTL in the contralesional hemisphere. These findings provide novel evidence concerning functional interactions between nodes of this fundamental cognitive network and sheds light on how these interactions are modified as a result of focal damage to MTL. The findings highlight that a reduced (top-down) influence of the MTL on ipsilateral language regions is accompanied by enhanced reciprocal coupling in the undamaged hemisphere providing a first demonstration of “connectional diaschisis.” 
Keyword Dynamic causal modeling
Effective connectivity
Magnetoencephalography (MEG)
Temporal lobe epilepsy
Working memory
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Queensland Brain Institute Publications
 
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