Avoidance task training potentiates phasic pontine-wave density in the rat: A mechanism for sleep-dependent plasticity.
Behavioral studies of learning and memory in both humans and animals support a role for sleep in the consolidation and integration of memories. The present study explored possible physiological mechanisms of sleep-dependent behavioral plasticity by examining the relationship between learning and state-dependent phasic signs of rapid eye movement (REM) sleep. Cortical electroencephalogram, electromyogram, eye movement, hippocampal theta-wave, and pontine-wave (P-wave) measures were recorded simultaneously in freely moving rats after a session of conditioned avoidance learning or a control session. After learning trials, rats spent 25.5% more time in REM sleep and 180.6% more time in a transitional state between slow-wave sleep and REM sleep (tS-R) compared with that in control trials. Both REM sleep and tS-R behavioral states are characterized by the presence of P-waves. P-wave density was significantly greater in the first four episodes of REM sleep after the learning session compared with the control session. Furthermore, the P-wave density change between the first and third REM sleep episodes was proportional to the improvement of task performance between the initial training session and the post-sleep retest session. These findings show that the increase in P-wave density during the post-training REM sleep episodes is correlated with the effective consolidation and retention of avoidance task learning.
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Sleep Research Laboratory, Program in Behavioral Neuroscience, and Department of Psychiatry, Boston University School of Medicine, Boston, Massachusetts 02118, USA. subimal@bu.edu
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D006624:Hippocampus / Q000502:physiology; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D011149:Pons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012153:Retention, Psychology / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology