Search

The current research methods, findings and questions that are being addressed in studies of the pharmacology of human memory and cognition are reviewed. Memory is not a unitary function. Neuropsychological studies of brain-damaged memory-impaired patients, as well as neuroimaging and drug studies in normal individuals indicate that different forms of learning and memory are subserved by different brain systems. Animal drug studies have also provided evidence that, while distinct, memory systems are not independent, but operate in close interaction with one another. Recent human studies of benzodiazepines and of cholinergic drugs demonstrate the value of the psychological models and of the experimental paradigms that are available from cognitive sciences for exploring how drugs alter cognitive and memory functions. They also show how drugs can be used as tools for analyzing the distinct neurochemical mechanisms underlying independent cognitive processes, and so find effective drugs rationally from a knowledge of the neurochemical bases of cognition. This research leads to specific recommendations concerning treatments that may improve memory functioning, for instance in Alzheimer's disease.

A single oral dose of 1.5mg of nicotine was administered to healthy young normal males in a placebo-controlled double-blind study. The nicotine produced a significant improvement in the number of words recalled from a 32 item list. An examination of the individual serial position curves showed that most subjects were recalling either predominantly from the first half of the list or predominantly from the second half of the list. Examination of these groups separately showed that nicotine improved recall for the part of the list that was being recalled better in the placebo condition. These results are consistent with the hypothesis that nicotine was supplying additional processing resources and that deployment of these is under the strategic control of the subject.

Subjects were trained with a light, a temporal cue and light-temporal cue combination as discriminative stimuli. These groups were tested with doses of scopolamine and it was found that the groups trained with one cue were more sensitive to the drug than the double cue group, although their pre-drug responding was comparable. A similar pattern was found among individuals in the double stimulus group where there was a significant correlation between dependency on a single cue, as shown in transfer tests, and drug sensitivity. These results were interpreted in terms of drug-induced changes in stimulus sensitivity due to a modification of the neural mechanisms controlling attention.

This paper reviews the use of cognitive models in human psychopharmacology to examine the role of the cholinergic system in memory and attention. We suggest that while studies of attention have continued to keep pace with developments in psychology, few studies have been reported which selectively test memory functions specified by current cognitive models of memory. We report the work from our laboratory which has demonstrated effects of cholinergic blockade on attention and memory, with particular emphasis on the work examining selective cholinergic mediation in working memory.

This study compared the effects of single nightly doses of flurazepam 30 mg and temazepam 40 mg upon both the subjective assessment of sleep quality and performance on 3 tests of mental efficiency 10 h following medication. 12 male and 12 female non-smoker subjects took part, none of whom experienced sleep difficulties. In comparison with their respective placebos, both hypnotics produced marked and significant improvements in the quality, depth and duration of sleep, and reduced the difficulty that the female subjects experienced in getting to sleep. Flurazepam also produced a significant increase in satisfaction with sleep together with significant reductions in the number of awakenings during the night and the level of clearheadedness on waking. The major test of performance was a continuous 20-min rapid visual information processing task. It was found that for both sexes during each of the two consecutive 10-min periods of performance flurazepam produced highly significant residual impairments in both the speed of reaction and the accuracy of detection, while temazepam had no effect. Overall the results indicate that flurazepam produces a wider range of improvements in sleep quality than temazepam at the cost of less clearheadedness on waking and residual impairments in sustained rapid information processing.