Hippocampal electrical stimulation and localisation of long-term episodic memory

Robin G. Morris, Steven G. Coleshill, Maria E. Lacruz, Antonio Valentin and Gonzalo Alarcon

in Epilepsy and Memory

Published in print June 2012 | ISBN: 9780199580286
Published online September 2012 | e-ISBN: 9780191739408 | DOI:
Hippocampal electrical stimulation and localisation of long-term episodic memory

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The clinical use of depth-electrode recording in the hippocampus in people undergoing neurosurgical treatment for epilepsy has also facilitated exploration of hippocampal memory function though stimulation techniques. This chapter reviews the few studies that have used these techniques, combining them with synchronous memory testing. Early studies used techniques involving after-discharges, with the disadvantage of imprecise investigation of focal functionality. More progress was made when subthreshold stimulation techniques were adopted and this led to specific theories about left and right hippocampal involvement. The chapter also introduces an arguably more refined technique termed single-pulse electrical stimulation (SPES), which uses single 1-ms pulses to produce approximately 100–300 ms cortical responses. The SPES technique has produced results indicating a specific role for the hippocampus in episodic memory — encoding rather than retrieval — here termed the gateway theory of hippocampal function.

Keywords: depth-electrode recording; hippocampus; epilepsy; hippocampal memory; subthreshold stimulation; single-pulse electrical stimulation; episodic memory; gateway theory of hippocampal function

Chapter.  6180 words.  Illustrated.

Subjects: Neuroscience

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