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Biomedical subjects

W T Roth

Publications and source records attributed to W T Roth.

At least 109 records · Page 6Linked to original sources
PubMed1978

Time course effects of marijuana and ethanol on event-related potentials.

Twelve male college students received orally on different days NIMH marijuana extract calibrated to contain 0.7 mg/kg delta-9-tetrahydrocannabinol, 1.0 ml/kg 95% ethanol, and placebo in a double-blind balanced-order design. The contingent negative variation (CNV), auditory evoked potential (EP), heart rate (HR), and subjective measures of intoxication were recorded prior to drug ingestion and at regular intervals for 4.5 h postdrug. Both drugs produced significant subjective effects. Marijuana increased HR but did not have a significant effect on CNV amplitude or EP peak amplitudes and latencies. Ethanol increased HR, but not significantly, and reduced CNV amplitude and N1-P2 amplitude. Time-action curves for ethanol's effect on subjective high, HR, and N1-P2 amplitude were parallel, peaking between 0.5 and 1.5 h postdrug and returning to baseline by the end of testing. Time-action curve for ethanol's effect on the CNV showed continuing amplitude reduction throughout the test session.

Adult↗
PubMed1978

Psychophysiological correlates of the practice of Tantric Yoga meditation.

Autonomic and electroencephalographic (EEG) correlates of Tantric Yoga meditation were studied in three groups of subjects as they progressed from normal consciousness into meditation. Groups differed in their level of meditation proficiency. Measures of skin resistance, heart rate, respiration, autonomic orienting responses, resting EEG, EEG alpha and theta frequencies, sleep-scored EEG, averaged evoked responses, and subjective experience were employed. Unlike most previously reported meditation studies, proficient meditators demonstrated increased autonomic activation during meditation while unexperienced meditators demonstrated autonomic relaxation. During meditation, proficient meditators demonstrated increased alpha and theta power, minimal evidence of EEG-defined sleep, and decreased autonomic orienting to external stimulation. An episode of sudden autonomic activation was observed that was characterized by the meditator as an approach to the Yogic ecstatic state of intense concentration. These findings challenge the current "relaxation" model of meditative states.

Adult↗
PubMed1978

Cortical slow potentials and the occipital EEG in congenital blindness.

In a group of 7 congenitally blind adults, electroencephalographic occipital alpha rhythms were absent, but slow negative cortical potentials (CNV) were recorded over the visual cortex and were similar to those of normally sighted controls. Frontal and central CNV amplitudes, but not auditory evoked potentials or reaction times, were decreased significantly in the blind. The results confirm the presence of a developmental EEG abnormality following early blindness, and demonstrate the independance of slow potential generation from rhythmic 8--12 c/sec EEG activity in deafferented visual cortex. Non-sensory specific, event-related potentials such as the Contingent Negative Variation may prove to be useful psychophysiological probes of residual cortical function in brain regions which are deprived of primary sensory input.

Adult↗
PubMed1978

The timing of CNV resolution in a memory retrieval task.

Twelve men performed the Sternberg memory retrieval task while the EEG and EOG were recorded. Subjects saw a target set of 1 to 4 digits followed by a warning tone that was followed after 1.5 sec by a probe digit. Subjects indicated by pressing one of two levers whether the probe digit was in or out of the target set. The timing of contingent negative variation (CNV) resolution was measured as the latency of 50% resolution in stimulus-synchronized waveforms (SSWs), response-synchronized waveforms (RSWs), and model waveforms (MWs). The MWs were constructed by adding each RSW to itself using time displacements derived from the reaction times of the single trials of which the RSW was an average. The results indicated that CNV resolution is related to the timing of the motor response. MWs had resolution latencies close to those of the SSWs. In SSWs the N1 and P3 to the warning tone also varied with target set size.

Adolescent↗
PubMed1978

Marijuana effects on associations to novel stimuli.

Sixteen college-educated male subjects were given an object description task during placebo conditions and while intoxicated with marijuana extract cookies calibrated to 0.3 mg/kg delta-9-tetrahydrocannabinol, a dose within the range of usual social use. The task was scored for fluency, flexibility, elaboration, and uniqueness, all of which represent associational thinking and are considered to be components of creativity. Marijuana did not enhance any of these measures.

Adult↗
PubMed1978

Slowing of short-term memory scanning in alcoholics.

Hospitalized alcoholics taking disulfiram were found to process information in short-term memory at a slower rate than hospitalized controls, although short-term memory capacity was similar in the two groups.

Adult↗
PubMed1977

Marijuana effects on long-term memory assessment and retrieval.

The ability of 16 college-educated male subjects to recall from long-term memory a series of common facts was tested during intoxication with marijuana extract calibrated to 0.3 mg/kg delta-9-tetrahydrocannabinol and during placebo conditions. The subjects' ability to assess their memory capabilities was then determined by measuring how certain they were about the accuracy of their recall performance and by having them predict their performance on a subsequent recognition test involving the same recall items. Marijuana had no effect on recall or recognition performance. These results do not support the view that marijuana provides access to facts in long-term storage which are inaccessible during non-intoxication. During both marijuana and placebo conditions, subjects could accurately predict their recognition memory performance. Hence, marijuana did not alter the subjects' ability to accurately assess what information resides in long-term memory even though they did not have complete access to that information.

Adolescent↗
PubMed1977

Ethanol and marihuana effects on event-related potentials in a memory retrieval paradigm.

Twelve men performed the Sternberg memory retrieval task under three experimental conditions: after oral doses of marihuana extract calibrated to contain 0.7 mg/kg delta9-tetrahydrocannabinol (THC), 1.0 ml/kg 95% ethanol, or placebo. Simultaneously, the EEG was recorded from Ca to linked ears and the EOG from leads above and below the right eye. In this task, subjects saw a set of 1 to 4 digits follwed by a warning tone that was followed 1.5 sec later by a test digit. Subjects indicated by pressing one of two buttons whether the test digit was in-set or out-of-the-set. There were no drug effects on N1 in the evoked potential to the warning tone, but P3 amplitude was smaller under THC and ethanol than under placebo. CNV amplitude in the interval between the warning tone and the test digit showed no drug effects, indicating that the subject was equally prepared for the test digit regardless of drug received. However, the latency of 50% resolution of the CNV was longer under THC than under placebo. THC also increased the reaction time for each set size by about 75 msec above the values for ethanol and placebo, the latter two not differing significantly. Set size affected N1 and P3 amplitudes and latencies and CNV amplitude, as well as 50% CNV resolution latency and reaction time, but there were no drug chi set size interactions.

Adolescent↗
PubMed1977

Marijuana and memory intrusions.

Sixteen college-educated male subjects were tested on free-recall lists during intoxication with marijuana extract calibrated to 0.3 mg/kg delta-9-tetrahydrocannabinol and during placebo conditions. On each testing day subjects studied six lists using a regular overt rehearsal procedure and six lists using an association-overt rehearsal procedure in which they were to rehearse alound both list items and associations to those items. Both marijuana and the association-rehearsal procedure reduced the number of correct recalls and increased the number of intrusions (nonlist items which were incorrectly recalled as having been on the list to be learned). The intrusions were divided into three categories: a) words found on prior lists; b) associates spoken during the rehearsal; or c) totally new works not previously mentioned. Marijuana significantly increased the number of new intrusions; the association-rehearsal procedure did not. This result suggests that one of the effects of marijuana on cognitive functions in humans is to increase the number of intrusive thoughts and this may be the mechanism involved in some of the thought disorder observed with marijuana intoxication.

Acute Disease↗
PubMed1976

Marijuana and ethanol: differential effects on time perception, heart rate, and subjective response.

Performance on a time production task, heart rate, and subjective responses were studied in twelve male sujects given oral doses of marijuana (0.7 mg of delta-9-tetrahydrocannabinol/kg), ethanol (1.0 ml/kg), and placebo, on three testing days which were each separated by 1 week. Orders were balanced across subjects and testing conditions were double-blind. Compared to ethanol and placebo, marijuana induced a significant under-production of time intervals, suggesting an acceleration of the internal rate of time perception. The onset of this acceleration of time sense in which geophysical time seemed to pass slowly corresponded with the characteristic increase in heart rate and the onset of the subjective feelings of drug effects. Initial phases of alcohol intoxication were associated with the opposite effects on the time production task. These findings replicate previous work and indicate that an easily administered time production task provides a consistent, non-motor measure of acute marijuana intoxication and also reflects ethanol intoxication.

Adult↗
PubMed1976

Parameters of temporal recovery of the human auditory evoked potential.

Auditory evoked potentials (AEPs) to tone pips at three monopolar scalters were systematically varied: tone intensity (3.0, 1.5 and 0.75 sec), and direction of attention. Interstimulus intervals were computed separately for the 9 different combinations of the three possible first prior intervals (intervals between the test stimulus and the stimulus immediately preceding it) and the three possible second prior intervals (intervals between the stimulus preceding the test stimulus and the stimulus prior to that). Our results show that temporal amplitude recovery of N1 and P2 can be based solely on the first prior interval had not effect on amplitude. Furthermore, they show that it is inadvisable to use combined N1-P2 amplitude measures since the two peaks appear to be governed by separate processes. Recovery for N1 was different from that of P2, N1 showed no intensity effects while P2 did, and N1 and P2 had different topographic distributions. Directing attention to the tones did not affect N1 or P2 amplitudes but caused a highly significant increase in both N1 and P2 latency. Attention to the tones also produced a frontal negative baseline shift following them.

Adult↗
PubMed1976

Attention effects on auditory evoked potentials to infrequent events.

In two experiments, evoked potentials (EPs) were obtained for three levels of attention, defined by instructions to press a button to, listen to or ignore an infrequent event. In experiment 1, a regular train of standard tone pips was occasionally and randomly interrupted by a tone of different pitch (pitch change) or by the omission of a tone (gap). At the vertex (Cz) a late positive peak (P3) to the infrequent event became larger and later with increased attention, while the earlier negative peak (N1) became later but not larger. In experiment 2, EPs to pitch changes were recorded from Cz, frontal (Fz) and parietal (Pz) locations. All effects obtained in experiment 1 were replicated. The distribution of P3 was different during the different attention conditions.

Acoustic Stimulation↗