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Biomedical subjects

E S Barratt

Publications and source records attributed to E S Barratt.

At least 37 records · Page 2Linked to original sources
PubMed1986

No decrement in visual P300 amplitude during extended performance of the oddball task.

Research indicates that in visual sustained attention paradigms, the amplitude of the P300 component of the event-related potential invoked by target (critical) stimuli shows a decrement in amplitude. This amplitude decrement parallels decrements in vigilance performance that result from the difficult discrimination that is typically required between the infrequent targets and the frequent nontargets (neutral stimuli). In contrast, target stimulus P300 does not appear to show a decrement across large numbers of trials during performance of the "oddball" paradigm, in which targets and nontargets are highly discriminable. The present study measured target and nontarget P300 amplitude during performance of a visual oddball paradigm extended over an interval of some 3 1/2 hours, a period well in excess of the 3/4 hour intervals employed in previous research. The results indicated no decrement in P300 amplitude as a function of time for either targets or nontargets. The only significant relationship between P300 and behavioral data was an inverse correlation across oddball runs between average nontarget P300 amplitude and total number of targets missed.

Adult↗
PubMed1985

Individual differences in visual event-related potentials: P300 cognitive augmenting/reducing parallels N100 sensory augmenting/reducing.

In a visual event-related potential experiment, both N100 augmenting/reducing data and oddball paradigm P300 data were collected from the same subjects. A significant correlation was obtained between augmenting/reducing and the degree to which stimulus probability affected P300 amplitude. Subjects who augment/reduce in response to increased stimulus brightness in the sensory domain also appear to augment/reduce in response to low probability in the cognitive domain.

Adult↗
PubMed1981

Impulsivity and paced tapping.

The purpose of this study was to test the hypothesis that impulsivity is positively related to both the intraindividual variability and the rate of performance of a paced tapping task. The independent variable in the tapping task were: feedback vs. no feedback; tempo; concurrent cognitive task (counting) vs. no concurrent cognitive task. Three measures of tapping performance were computed: absolute or total error of tapping, tapping rate, and the intraindividual variability of tapping. The results confirm the hypothesis that impulsivity is positively related to rate of paced tapping, although the degree of relationship varied under different experimental conditions within the paced tapping task. Intraindividual variability of tapping was not significantly related to impulsivity, but the results were suggestive of a positive relationship.

Journal Article↗
PubMed1976

Effect of chronic pentobarbital treatment on the sleep patterns of squirrel monkeys.

Following a 30-day baseline, 60 days of sodium pentobarbital treatment (5 mg/kg) were given to squirrel monkeys 2 h prior to the start of a 12-h recording of EEG and EOG. Following the drug-treatment phase, an additional 30-day period was used to determine the rate of recovery. Repeated pentobarbital treatment significantly reduced awake time and slow wave sleep while it elevated the time spent in drowsy and light sleep. The recovery phase indicated a brief recovery of rapid eye movement sleep while the other stages failed to return to baseline levels. The cyclical nature of the changes observed with chronic pentobarbital suggest the importance of circadian fluctuations in the study of chronic drug treatment and the sleep-wakefulness process.

Animals↗
PubMed1976

Effects of rapid depletion of phenylalanine and tyrosine on sleep and behavior.

The effects of fluctuations of free amino acid concentrations in plasma on sleep patterns and operant behavior in the squirrel monkey were studied. Plasma phenylalanine (PHE) and tyrosine (TYR) were rapidly lowered to trace levels within 4 hr by intraperitoneal administration of phenylalanine ammonia-lyase (PAL), an enzyme which specifically deaminates both PHE and TYR to inactivate products. Significant alterations in sleep patterns and in performance on a chained operant task involving hold and reaction time components were found, but no significant effect on the performance of a simple operant task was observed. Adminstration of saline or trans-p-cinnamic acid and trans-p-coumaric acid, the products of PHE and TYR deamination, produced no changes in behavior or sleep patterns. The reduction of plasma PHE and TYR resulted in a significant decrease in PHE and TYR levels in whole rat brain. Brain serotonin levels were increased within 4 hr after PAL administration, whereas, dopamine and norepinephrine levels were decreased subsequently (within 8 hr). These studies suggest that circulating levels of PHE and TYR are involved directly or indirectly in the modulation of certain parameters of brain function.

Animals↗
PubMed1975

Role of biogenic amines in the effects of marijuana on EEG patterns in cats.

The results of pretreatment with drug having selective action on brain biogenic amine levels on the subsequent effects of acute marijuana treatment were assessed for behavior and EEG measures. Behavioral changes and alterations in the spontaneous EEG indicated that pretreatment with drugs affecting brain levels of 5-HT was most effective in altering the dual properties of acute marijuana treatment. The present findings support the interpretation that the availability of serotonin interacts with the effects of acute marijuana treatment but do not eliminate the possible involvement of other neurotransmitters in the action of marijuana.

5-Hydroxytryptophan↗
PubMed1975

Effects of stereotactic cingulumotomy on a sequential motor task in man.

The effect of bilateral cingulumotomy on sequential tapping behavior was investigated in 6 patients, Contrary to previous clinical studies and predictions derived from data on cingulate lesions in the rat, a consistent decrement in postoperative performance was not found. Temporal integration of behavior in man, as measured in terms of accuracy of sequential motor performance, does not appear to be critically dependent upon the integrity of the cingulum bundle at the level of interruption investigated in the present study.

Adult↗
PubMed1975

Effect of chronic marijuana administration of stages of primate sleep-wakefulness.

The effects of the repeated administration of delta-9-tetrahydrocannabinol on sleep-wakefulness patterns were studied in adult male squirrel monkeys. The percent time spent in slow wave sleep was reduced with chronic treatment and failed to return to base line levels after 30 days of recovery. The amount of time spent in Stage 1 or drowsy state increased with repeated treatment and remained elevated through recovery. Changes observed in other stages of sleep-wakefulness were sensitive to repeated treatment with marijuana but were found to return to base line levels during recovery.

Administration, Oral↗