Biomedical subjects

R R Stanny

Publications and source records attributed to R R Stanny.

6 recordsLinked to original sources

PubMed1999

Error-related processing during a period of extended wakefulness.

The nature of error detection as manifested by the error-related negativity was examined in both a Sternberg memory search task and a visual search task. Both tasks were performed in conditions with consistent or varied stimulus-response mapping and loads of three or six letters. After subjects were trained extensively in all conditions, they performed the tasks throughout the night without sleeping. The data suggest that the effectiveness of error detection decreases over time because of a decrease in the quality of perceptual processing. Error detection also suffers when performance requires more search-related resources. In both cases, the representation of the correct response is compromised. These results indicate that error detection depends on the same perceptual and cognitive processes that are required for correct performance.

Adult↗

PubMed1996

Methamphetamine effects on cognitive processing during extended wakefulness.

We examined the effects of both 5- and 10-mg/7O kg body weight of d-methamphetamine HCl on high event rate vigilance and tracking performance in a 13.5-hr sustained-performance session during one night of sleep loss. At 0116 hours participants were administered either a 5 mg/70 kg oral dose of d-methamphetamine (n=10), 10 mg/70 kg d-methamphetamine (n=10), or a placebo (n=10) using standard double-blind procedures. Performance on all measures degraded markedly during the night in the placebo group. Both the 5- and 10-mg methamphetamines treatment reversed an initial decline in d', and reversed increases in nonresponses (lapses) and tracking error within approximately 3 hr of administration. No evidence that amphetamine treatment increased impulsive responding (fast guesses) was observed. The magnitude of the performance effects of the methamphetamine treatments was similar at 3 hr postadministration. However, the effects of the 5-mg dose were shorter-lived, disappearing by the last testing session (6.5 hr postadministration), whereas effects of the 10-mg dose tended to remain throughout testing. Both amphetamine treatments decreased subjective sleepiness during the night and tended to increase subjective sleep latencies during a post-testing sleep period.

Adult↗

PubMed1995

The effects of tyrosine on cognitive performance during extended wakefulness.

Tyrosine, a large neutral amino acid found in dietary proteins, has received recent attention as a potential treatment for stress. The behavioral effects of tyrosine were examined during an episode of continuous nighttime work involving one night's sleep loss. Subjects performed nine iterations of a battery of performance tasks and mood scales for approximately 13 h, beginning at 1930 and ending at 0820. They remained awake throughout the day on which the experiment began and were awake for more than 24 h by the end of testing. Six hours after the experiment began, one-half of the subjects received 150 mg.kg-1 tyrosine in a split dose while the other half received cornstarch placebo in a double-blind procedure. Tyrosine administration was associated with a significant amelioration of the usual performance decline on a psychomotor task and a significant reduction in lapse probability on a high-event-rate vigilance task. The improvements lasted on the order of 3 h. The results of this study also suggest that tyrosine is a relatively benign treatment at this dose. After further testing with other doses and timing of administration, tyrosine may prove useful in counteracting performance decrements during episodes of sustained work coupled with sleep loss.

Adult↗

PubMed1994

Influence of extended wakefulness on automatic and nonautomatic processing.

We investigated the influence of extended wakefulness on automatic and nonautomatic processes in memory and visual search tasks. Subjects were trained in consistently mapped and variably mapped versions of each task, attaining automatic performance in the consistently mapped versions. We then recorded performance measures and event-related brain potentials for a 14-h period that began during the evening of the last day of training. Overall performance declined with extended wakefulness, but the benefits of consistently mapped training were retained throughout the night. Performance decrements consisted of an increase in nonresponses, increased response latencies, and decreased accuracies. P300 latencies increased, and P300 amplitudes decreased with extended wakefulness. When viewed together, reaction time and event-related brain potentials measures suggest that the locus of extended wakefulness effects was during early perceptual processes.

Adult↗

PubMed1980

An "inhibitory" influence on brainstem population responses.

Forward masking was used to obtain measurements of physiological masking and two-tone unmasking from short-latency evoked potentials and psychophysical responses in human subjects. The physiological results are in qualitative agreement with data on inhibitory phenomena in nonhuman auditory systems. The neural and behavioral data obtained thus far agree well.

Auditory Pathways↗

PubMed1980

A short-term memory influence on the N1 response of cerebral cortex.

The N1 component of auditory evoked potentials varies in amplitude as a function of the direction of attention and has been treated as a physiological correlate of stimulus set. Results from a sequential pitch memory experiment, presented here, show that N1 also indexes the strengths of short-term associations, suggesting that the N1 mechanism(s) may be involved in a more general process of organizing and/or maintaining temporary sensorimotor memories.

Adult↗