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This Article Full Text Full Text (PDF) All Versions of this Article: 586/14/3479    most recent jphysiol.2008.153254v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Escudero, M. Articles by Márquez-Ruiz, J. PubMed PubMed Citation Articles by Escudero, M. Articles by Márquez-Ruiz, J. Related Collections Neuroscience Related Article

¹ Neurociencia y Comportamiento, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla, Spain

Eye movements, ponto-geniculo-occipital (PGO) waves, muscular atonia and desynchronized cortical activity are the main characteristics of rapid eye movement (REM) sleep. Although eye movements designate this phase, little is known about the activity of the oculomotor system during REM sleep. In this work, we recorded binocular eye movements by the scleral search-coil technique and the activity of identified abducens (ABD) motoneurons along the sleep–wake cycle in behaving cats. The activity of ABD motoneurons during REM sleep was characterized by a tonic decrease of their mean firing rate throughout this period, and short bursts and pauses coinciding with the occurrence of PGO waves. We demonstrate that the decrease in the mean firing discharge was due to an active inhibition of ABD motoneurons, and that the occurrence of primary and secondary PGO waves induced a pattern of simultaneous but opposed phasic activation and inhibition on each ABD nucleus. With regard to eye movements, during REM sleep ABD motoneurons failed to codify eye position as during alertness, but continued to codify eye velocity. The pattern of tonic inhibition and the phasic activations and inhibitions shown by ABD motoneurons coincide with those reported in other non-oculomotor motoneurons, indicating that the oculomotor system – contrary to what has been accepted until now – is not different from other motor systems during REM sleep, and that all motor systems are receiving similar command signals during this period.

(Received 26 February 2008; accepted after revision 20 May 2008; first published online 22 May 2008)
Corresponding author M. Escudero: Neurociencia y Comportamiento, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain. Email: mescudero{at}us.es

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