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Biomedical subjects

A W Gaillard

Publications and source records attributed to A W Gaillard.

12 recordsLinked to original sources
PubMed1979

Some effects of an ACTH 4-9 analog (Org 2766) on human performance.

The effects (on human beings) of the ACTH analog Org 2766 were investigated for a range of performance tests: complicated serial reaction task, running memory span, verbal learning and non-verbal mental ability tests (closure flexibility and non-verbal abstraction). Subjective ratings on feelings were taken and heart rate was measured. Only the 30-min reaction task produced significant drug effects. In this task performance tends to deteriorate as a function of time on task. During the test period there is a gradual increase in the number of lapses in performance due to moments of inattention. This deterioration is counteracted by the ACTH 4-9 analog, a result also found in previous study using ACTH 4-10 (Org OI63). Thus ACTH fragments which are devoid of endocrine effects seem to have a beneficial effect on goal-directed motivation oriented on the requirements of the task.

Adrenocorticotropic Hormone↗
PubMed1979

The terminal CNV and stimulus discriminability in motor and sensory tasks.

Slow EEG potentials were recorded during the foreperiod of a signal detection task which involved different levels of discrimination difficulty. The subject was required to react to S2 as quickly as possible or to delay his response by 1 s. It was found that the contingent negative variation (CNV) was attenuated when no speeded response was required and that larger amplitudes preceded the easy rather than the difficult discrimination. In addition, no differences were found between correct and incorrect detections. On these grounds it is concluded that the CNV is not positively correlated with perceptual sensitivity.

Cerebral Cortex↗
PubMed1977

Drug effects on EEG frequency spectra as a function of interstimulus interval.

The frequency spectra of EEG background activity preceding the stimulus in a serial simple RT task were investigated as a function of interstimulus interval (ISI). The percentage of power in the alpha and theta bands increased with longer ISIs while the delta activity decreased. Additionally, the effects of an amphetamine and a barbiturate were investigated. The increase in alpha activity with longer ISI conditions were larger after barbiturate than after placebo, while it remained constant after amphetamine treatment. Contrary to expectation, no systemic changes in alpha activity were found during the 3-h session for any of the treatments. It is suggested that the background EEG during the foreperiod of an RT task mainly reflects phasic arousal. The characteristics of the background EEG in the present experimental situation may be quite different from that recorded under "relaxed" no-task conditions.

Adult↗
PubMed1976

Effects of warning-signal modality on the contingent negative variation (CNV).

CNVs were recorded during the S1-S2 interval of a prolonged simple reaction task. In the task, a warning stimulus S1 is followed by an imperative stimulus S2, to which the subject makes a motor response. The differential effects of a visual and an auditory S1 were investigated under two interstimulus interval (ISI) durations (1 and 3 sec). Under the 3 sec ISI condition, the form of the slow negative wave demonstrated clearly a biphasic character: an orientation wave (O wave) following S1 with a peak latency at about 650 msec and an expectancy wave (E wave), which reaches its largest amplitude towards the end of the ISI. Under the 1 sec ISI condition the two components of the CNV are confounded. The O wave had a fronto-central distribution, while the E wave was located precentrally. The O wave was enhanced after an auditory S1, as compared to a visual S1.

Acoustic Stimulation↗
PubMed1975

Some effects of ACTH 4-10 on performance during a serial reaction task.

Eighteen subjects worked continuously for half an hour in a self-paced reaction task. Half of the subjects were injected with ACTH 4-10 (30 mg/s.c.) and the other half with a placebo. The subjects injected with ACTH 4-10 showed a larger improvement in reaction time during the experimental session than the placebo group. However, this effect disappeared in a short retest, which was given half an hour after the experimental session. These results suggest that ACTH 4-10 has no effect on skill acquisition, but counteracts the build-up of reactive inhibition during the experimental session; that is, the peptide suppresses the decrease in motivation, which usually occurs during continuous performance tasks. This notion is confirmed by an analysis of the frequency distributions of the reaction times. Treatment effects were only found for the long reaction times. Long reaction times tend to occur with increasing frequency as a function of time-on-task and are an indication for the level of motivation of the subject. It was concluded that ACTH 4-10 counteracts the usual decay in performance as a function of time-on-task due to increasing boredom and mental fatigue.

Adrenocorticotropic Hormone↗