Biomedical subjects

Carlyle T Smith

Publications and source records attributed to Carlyle T Smith.

4 recordsLinked to original sources

PubMed2006

Post-training intra-striatal scopolamine or flupenthixol impairs radial maze learning in rats.

Systemic treatments with acetylcholine (ACh) or dopamine (DA) receptor antagonists during hours 0-4 but not during hours 5-8 following training on a radial arm maze (RAM) or lesions of the dorsal striata impair learning. This suggested that intra-striatal infusions of ACh or DA receptor antagonists during hours 0-4 following training may impair learning. Rats were randomly assigned to groups (ns=5-11) receiving dorsal striatal infusions of the ACh receptor antagonist scopolamine (0-18 microg/microL at 0 and 2h or at 4 and 6h after training), the DA receptor antagonist cis-flupenthixol (0-25 microg/microL at 0, 4 or 12h after training) or the inactive isomer trans-flupenthixol (6 microg/microL at 0 h after training). Scopolamine and cis-flupenthixol impaired the habit-learning version of the task. Given after hours 0-4 following training, the effects of scopolamine were diminished but those of cis-flupenthixol were not. Trans-flupenthixol produced less impairment than cis-flupenthixol. Results suggest that ACh and DA receptors in the dorsal striatum during hours 0-4 following training play a role in habit learning.

Acetylcholine↗

PubMed2006

Learning-dependent changes in sleep spindles and Stage 2 sleep.

It has become increasingly clear that sleep is necessary for efficient memory consolidation. Recently, it has been found that Stage 2 sleep disruption impairs procedural memory performance, and that memory performance is correlated with the duration of Stage 2 sleep; but the mechanisms involved in synaptic plasticity for procedural memory during sleep have not been identified. The present study examined the learning-dependent changes in sleep, including Stage 2 sleep spindles. Following an intense period of simple motor procedural learning, the duration of Stage 2 sleep and spindle density increased. There were no changes observed in the duration of any other stage of sleep or in the density of rapid eye movements. These findings support the hypothesis that sleep spindles are involved in the off-line reprocessing of simple motor procedural memory during Stage 2 sleep.

Adult↗

PubMed2004

Scopolamine during the paradoxical sleep window impairs radial arm maze learning in rats.

It has been proposed that there are paradoxical sleep windows (PSW) during which REM sleep is required for effective learning. Thus, rats deprived of REM sleep during 0-4 (but not 5-8) h after training show impaired learning of a radial maze task. As cholinergic (ACh) systems are active during REM sleep and may be involved in learning, this experiment investigated the effects on learning of pharmacological manipulation of the cholinergic system during the period identified as the PSW. Sprague-Dawley rats were randomly assigned to groups that were physically deprived of REM for 4 h either immediately after training or beginning 4 h after training or treated with the ACh receptor antagonist scopolamine (0-0.4 mg/kg at 0 and 2 h after training or 0.006 mg/kg at 4 and 6 h after training) on each of 9 days of radial maze training. Post-training REM deprivation (0-4 h but not 5-8 h after training) and scopolamine dose-dependently impaired learning. Results suggest that REM sleep and intact ACh neurotransmission are required during the PSW for rats to learn the radial maze task.

Animals↗

PubMedDate not supplied

Posttraining increases in REM sleep intensity implicate REM sleep in memory processing and provide a biological marker of learning potential.

Posttraining rapid eye movement (REM) sleep has been reported to be important for efficient memory consolidation. The present results demonstrate increases in the intensity of REM sleep during the night of sleep following cognitive procedural/implicit task acquisition. These REM increases manifest as increases in total number of rapid eye movements (REMs) and REM densities, whereas the actual time spent in REM sleep did not change. Further, the participants with the higher intelligence (IQ) scores showed superior task acquisition scores as well as larger posttraining increases in number of REMs and REM density. No other sleep state changes were observed. None of the pretraining baseline measures of REM sleep were correlated with either measured IQ or task performance. Posttraining increases in REM sleep intensity implicate REM sleep mechanisms in further off-line memory processing, and provide a biological marker of learning potential.

Adult↗