The exact neurophysiological and electrophysiological mechanisms underlying the involvement of sleep in the process of memory consolidation are still poorly understood. Recent findings point to the involvement of slow EEG rhythms in post-learning plasticity. However, little is known about the relationships between memory consolidation and hippocampal EEG features. The aim of the present study is to assess the effects of both procedural and declarative learning on qualitative and quantitative measures of sleep directly recorded from the hippocampus. Scalp EEG and intracerebral (hippocampal and neocortical) stereo-EEG was recorded in eight epileptic patients undergoing presurgical evaluations. After a baseline night, sleep was recorded after the counterbalanced administration of declarative (paired-associate word list learning task) and procedural (sequential finger tapping task) tasks. On morning retest, patients correctly recalled more word pairs than pre-sleep, and were tendentially faster on the motor task. Standard polysomnography showed an increase of slow wave sleep (SWS) amount only after procedural learning, accompanied by an increase of hippocampal SEEG power in the very low frequency range (0.5–1 Hz) during the first NREM sleep cycle. This is the first study reporting about the local effects of declarative and procedural learning on sleep recorded from both scalp and intracranial derivations. The increase of power in the very low frequency range can be interpreted, in the frame of the synaptic homeostasis hypothesis, as reflecting the need of the hippocampal neurons to regain the synaptic balance altered by presleep learning. Sleep-dependent plastic modifications of the hippocampal activation have been previously reported after learning the very same procedural task used here. Moreover, it has been recently shown that the hippocampus is not the main site of activity during either learning or recall of the same declarative task employed in the present study, maybe because used words are already well
Changes in the human hippocampal very low frequencies after learning / Ferrara, M; Moroni, Fabio; Nobili, L; DE CARLI, F; Tempesta, D; DE GENNARO, Luigi; Francione, S; LO RUSSO, G.. - In: JOURNAL OF SLEEP RESEARCH. - ISSN 0962-1105. - 17:(2008), pp. 535-535. (Intervento presentato al convegno 19th ESRS Congress tenutosi a Glasgow).
Changes in the human hippocampal very low frequencies after learning.
MORONI, FABIO;DE GENNARO, Luigi;
2008
Abstract
The exact neurophysiological and electrophysiological mechanisms underlying the involvement of sleep in the process of memory consolidation are still poorly understood. Recent findings point to the involvement of slow EEG rhythms in post-learning plasticity. However, little is known about the relationships between memory consolidation and hippocampal EEG features. The aim of the present study is to assess the effects of both procedural and declarative learning on qualitative and quantitative measures of sleep directly recorded from the hippocampus. Scalp EEG and intracerebral (hippocampal and neocortical) stereo-EEG was recorded in eight epileptic patients undergoing presurgical evaluations. After a baseline night, sleep was recorded after the counterbalanced administration of declarative (paired-associate word list learning task) and procedural (sequential finger tapping task) tasks. On morning retest, patients correctly recalled more word pairs than pre-sleep, and were tendentially faster on the motor task. Standard polysomnography showed an increase of slow wave sleep (SWS) amount only after procedural learning, accompanied by an increase of hippocampal SEEG power in the very low frequency range (0.5–1 Hz) during the first NREM sleep cycle. This is the first study reporting about the local effects of declarative and procedural learning on sleep recorded from both scalp and intracranial derivations. The increase of power in the very low frequency range can be interpreted, in the frame of the synaptic homeostasis hypothesis, as reflecting the need of the hippocampal neurons to regain the synaptic balance altered by presleep learning. Sleep-dependent plastic modifications of the hippocampal activation have been previously reported after learning the very same procedural task used here. Moreover, it has been recently shown that the hippocampus is not the main site of activity during either learning or recall of the same declarative task employed in the present study, maybe because used words are already wellI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
