Neurotoxic lesions of phasic pontine-wave generator cells impair retention of 2-way active avoidance memory

• Published in: Sleep (New York, N.Y.) N.Y.), 2004-11, Vol.27 (7), p.1282-1292
• Main Authors: MAVANJI, Vijayakumar, ULLOOR, Jagadish, SAHA, Subhash, DATTA, Subimal
• Format: Article
• Language: English
• Subjects: Anatomical correlates of behavior; Animal; Animals; Avoidance Learning - drug effects; Avoidance Learning - physiology; Behavioral psychophysiology; Biological and medical sciences; Brain Mapping; Brain Stem - drug effects; Brain Stem - physiology; Fundamental and applied biological sciences. Psychology; Ibotenic Acid - pharmacology; Learning. Memory; Male; Memory; Microinjections; Neural Pathways - drug effects; Neural Pathways - physiology; Neurons - drug effects; Neurons - physiology; Neurotoxins - pharmacology; Polysomnography - drug effects; Pons - drug effects; Pons - physiology; Prosencephalon - drug effects; Prosencephalon - physiology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Sprague-Dawley; Retention (Psychology) - drug effects; Retention (Psychology) - physiology; Sleep, REM - drug effects; Sleep, REM - physiology; Sleep. Vigilance; Vertebrates: nervous system and sense organs
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleep/27.7.1282

The aim of this study was to test the hypothesis that the activation of pontine (P)-wave generator is critical for the posttraining rapid eye movement (REM) sleep-dependent memory processing. Ibotenic acid was microinjected (0.5 microg in 0.05 microL) into the functionally identified P-wave generator in order to destroy the cell bodies and thus to study the effects of their destruction upon waking-sleep states, P-waves, and 2-way active avoidance memory. Sleep research laboratory at Boston University School of Medicine. Adult male Sprague-Dawley rats (N = 27). Chronically implanted for recording polygraphic signs of sleep and bilateral guide tubes for the local microinjections into the P-wave generator. The ibotenic acid produced a small spherical area (< or = 0.35 mm in diameter) of nerve cell loss centered on the P-wave generator. Bilateral lesioning of the P-wave generator decreased P-waves during REM sleep by > 95% without significantly changing the amounts of time spent in wake, slow-wave sleep, or REM sleep. In these P-wave generator-lesioned rats, acquisition of avoidance learning and posttraining wake-sleep changes were identical to those of the sham-lesioned rats. However, in the test trials, after 6 hours of undisturbed sleep-wake, P-wave generator-lesioned rats had no retention of avoidance memory. These findings, for the first time, provide direct evidence that P-wave-generating cells are critical for normal REM sleep-dependent memory processing. This evidence supports our hypothesis that the P-wave generator in the brainstem may act as an on switch to provide activating input to forebrain structures for sleep-dependent memory processing.