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Biomedical subjects

D R Thorne

Publications and source records attributed to D R Thorne.

11 recordsLinked to original sources
PubMed1992

Sleep deprivation and impaired cognition. Possible role of brain catecholamines.

To assess the role of brain catecholamines in cognitive decline associated with sleep deprivation, 40 healthy male volunteers were randomized to conditions of total sleep deprivation or 40.5 h of rest. Within each sleep condition, subjects were further randomized to treatment with a 2-day regimen of placebo or alpha-methyl-para-tyrosine (AMPT), a catecholamine synthesis inhibitor. Cognitive performance was measured repeatedly over time using a computerized performance assessment battery. Treatment with AMPT or treatment with sleep deprivation increased sleepiness without producing marked or consistent deterioration in performance. By contrast, subjects who received both treatments reported greater sleepiness than those receiving either treatment alone, and developed severe cognitive impairment on a variety of tasks. These findings, along with previous evidence that catecholamine-enhancing drugs improve performance in sleep-deprived individuals, support the view that decline in cognitive performance during sleep deprivation may be mediated by brain catecholamines.

Adult↗
PubMed1992

Parsing attentional components during a simple reaction time task using sleep deprivation and amphetamine intervention.

To examine the independent contributions of the attentional components of arousal and activation in performance, sleep deprivation was used as the attentional manipulation in a reaction time (RT) task. The subjects were 18 men who underwent 63 hr. of sleep deprivation during which time they periodically performed a simple auditory RT task with manipulations of temporal uncertainty and intensity. After 48 hr. sleep deprivation, subjects ingested either 20 mg d-amphetamine or placebo, then continued testing throughout Day 3. During sleep deprivation, performance was more impaired on trials associated with low temporal uncertainty (arousal) and high preparation (activation) than on trials associated with high temporal uncertainty and low preparation. Analysis indicated that sleep deprivation perturbed activation, leaving arousal relatively unimpaired and that amphetamine had a restorative effect on the sleep deprivation-impaired activation system. The stimulus of high intensity was disruptive on Day 1 but facilitative on Day 3, a result which was interpreted as an initial inhibition, then disinhibition of arousal. Results were interpreted to indicate that, in some instances, alterations in the less specific arousal and activation systems may underlie impairment or changes in the more specific information processing and motor output stages.

Adult↗
PubMed1990

Circadian variation in human performance evaluated by the Walter Reed performance assessment battery.

As part of a two clock-time (0830 versus 2030) evaluation of administration-time dependent effects of dexedrine (5 mg) and triazolam (0.25 mg) on human cognitive performance, placebo (control) studies were conducted on 12 diurnally active (0700-2300) male adults (23-38 yrs) using a double-blind, randomized crossover design. Testing was conducted hourly during a series of sleepless 13-hr spans commencing in the morning or evening, using the Walter Reed computer controlled and scored multi-task cognitive performance assessment battery. For the placebo condition, Single and Group Cosinor analyses documented circadian rhythms in performance for most tasks (reaction time, logical reasoning, serial add/subtract and spatial orientation) both for individuals and the group. Overall, performance was worse overnight, when sleepiness was greatest, and best between 1830 and 2030. It was most variable around 0600-0700. The day-night variation in performance over all cognitive tests amounted to 21% of the 24-hr mean.

Adult↗
PubMed1989

Perceptual distortions and hallucinations reported during the course of sleep deprivation.

Subjects worked 30 to 45 min. of each hour for either 48 (n = 2) or 72 hr. (n = 8) without sleep. The frequency of reported visual task-related perceptual distortions and hallucinations showed both a linear increasing component and a strong circadian component. Perceptual distortions were most frequent in the late night-early morning hours (0400) and least frequent in the late afternoon-early evening hours (1600-2000).

Adolescent↗
PubMed1976

Sulfated glycoproteins, glycolipids, and glycosaminoglycans from synaptic plasma and myelin membranes: isolation and characterization of sulfated glycopeptides.

In this report we provide biochemical evidence that a highly purified synaptic plasma membrane fraction derived from rat brain, after intraventricular injection of 35S-labeled sodium sulfate, is enriched in a number of large sulfated glycoproteins compared with a purified myelin fraction studied concurrently. A fraction of the detergent-solubilized sulfated glycoprotein bound specifically to concanavalin A-Sepharose. In addition, we have identified the 35S-labeled lipid-soluble material in these membrane fractions as cerebroside sulfate. The sulfated protein in the lipid-extracted membranes was shown to consist predominantly of a class of glycoproteins containing sulfate in ester linkage to oligosaccharide chains, which are differentiated structurally from the sulfated glycosaminoglycans of brain. These two classes of sulfated macromolecules were distinguished from one another by several chemical and physical parameters. We present the chemical characterization of the sulfated glycopeptides derived from synaptic plasma and myelin membranes by extensive proteolytic digestion after quantitative removal of cerebroside sulfate. Membrane-associated glycosaminoglycans, either specifically or adventitously associated with these neuronal membranes, were quantitatively precipitated and identified.

Amino Acids↗
PubMedDate not supplied

The Walter Reed performance assessment battery.

This paper describes technical details of a computerized psychological test battery designed for examining the effects of various state-variables on a representative sample of normal psychomotor, perceptual and cognitive tasks. The duration, number and type of tasks can be customized to different experimental needs, and then administered and analyzed automatically, at intervals as short as one hour. The battery can be run on either the Apple-II family of computers or on machines compatible with the IBM-PC.

Cognition Disorders↗