Chapter

Electrophysiological studies of memory in epilepsy

Thomas Grunwald and Manila Vannucci

in Epilepsy and Memory

Published in print June 2012 | ISBN: 9780199580286
Published online September 2012 | e-ISBN: 9780191739408 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780199580286.003.0018
Electrophysiological studies of memory in epilepsy

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Invasive recordings of event-related potentials (ERPs) from depth electrodes within the human hippocampal formation have identified novelty detection as an important subprocess that contributes to encoding for verbal memory. N400 potentials associated with this process correlate with neuronal density of the hippocampal CA1-region and can be selectively reduced by the NMDA-receptor blocker ketamine. Together with the finding that NMDA-receptor dependent long-term potentiation can readily be induced only in slices of non-sclerotic but not of sclerotic human hippocampi these results suggest that successful encoding for verbal memory is mediated by NMDA-receptor dependent novelty detection within the human hippocampal system and that hippocampal sclerosis interferes with this process. Moreover, hippocampal ERP recordings indicate that temporal lobe epilepsy can interfere with the hippocampal differentiation between pictures of real and nonsense objects thus suggesting that impaired encoding of visual-semantic attributes of objects may contribute to visual memory deficits.

Keywords: temporal lobe epilepsy; event-related potentials; depth electrodes; N400; P600; late negative component; novelty detection

Chapter.  6996 words.  Illustrated.

Subjects: Neuroscience

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