title: Instrumental learning: an animal model for sleep dependent memory enhancement.
abstract: The relationship between learning and sleep is multifaceted; learning influences subsequent sleep characteristics, which may in turn influence subsequent memory. Studies in humans indicate that sleep may not only prevent degradation of acquired memories, but even enhance performance without further practice. In a rodent instrumental learning task, individual differences occur in how fast rats learn to associate lever pressing with food reward. Rats habitually sleep between learning sessions, and may differ in this respect. The current study assessed if the instrumental leaning paradigm could serve as a model to study sleep-dependent memory enhancement. Male Wistar rats performed 2 sessions of instrumental learning per day for 1-3 days. Electroencephalography was recorded both before and after the sessions. Sleep deprivation (3 h) was applied between the first and second session in a subgroup of rats. Measurements comprised the number of lever presses in each session, slow wave sleep (SWS) duration, Rapid Eye Movement Sleep (REMS) duration and sleep spindles. Baseline sleep parameters were similar for fast and slow learning rats. Task-exposure increased REMS-duration. The increase in REMS-duration was observed specifically after sessions in which learning occurred, but not after a later session. Sleep deprivation during the 3h period between the initial two sessions interfered with performance enhancement, but did not prevent this in all rats. Our considered movement control protocol induced partial sleep deprivation and also interfered with performance enhancement. The classic instrumental learning task provides a practical model for animal studies on sleep-dependent memory enhancement.
authors.affiliation: Department of Sleep and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands. cathalijnleenaars@zonnet.nl
authors.forename: Cathalijn H C
authors.initials: CH
authors.lastname: Leenaars
authors.forename: Carlos E N
authors.initials: CE
authors.lastname: Girardi
authors.forename: Ruud N J M A
authors.initials: RN
authors.lastname: Joosten
authors.forename: Irene M
authors.initials: IM
authors.lastname: Lako
authors.forename: Emma
authors.initials: E
authors.lastname: Ruimschotel
authors.forename: Maaike A J
authors.initials: MA
authors.lastname: Hanegraaf
authors.forename: Maurice
authors.initials: M
authors.lastname: Dematteis
authors.forename: Matthijs G P
authors.initials: MG
authors.lastname: Feenstra
authors.forename: Eus J W
authors.initials: EJ
authors.lastname: Van Someren
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003216:Conditioning, Operant / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D023421:Models, Animal; D011597:Psychomotor Performance / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012890:Sleep / Q000502:physiology*