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Biomedical subjects

A Pfefferbaum

Publications and source records attributed to A Pfefferbaum.

At least 127 records · Page 7Linked to original sources
PubMed1979

Age effects on event-related potentials in a selective attention task.

We used an event-related brain potential (ERP) technique developed by Hillyard et al. (1973) to test abilities to attenuate irrelevant stimuli and to detect target stimuli. Subjects, 12 healthy old (80.3 years) and 12 healthy young adults (22.0 years), heard 1500 Hz tones in one ear and 800 Hz tones in the other ear. Infrequently, the pitch of either tone was raised. During one run, infrequent tones in the right ear were targets, and in the other run those in the left ear were targets. Subjects counted targets. For both groups, an early component of the ERP (N1) was larger to tones in the attended ear than in the unattended ear, and a later component (P3) was largest to the target. This suggests that both groups can attenuate irrelevant stimuli and can use stimulus probability information in this task. That P3 was later for old subjects suggests that they take longer to decide stimulus relevance.

Acoustic Stimulation↗
PubMed1979

Intolerance and extremism in a correctional institution: a perceived ethnic relations approach.

The authors used an ecological approach to analyze the interaction of ethnicity, environment, personality, and ideology that led to racial intolerance, ethnic strife, and the existence of a self-styled neo-Nazi group in a correctional institution for youthful offenders. Staff members completed a questionnaire on which they rated the behavior of each of 320 inmates toward his own and other ethnic groups. The inmate's membership, if any, in a "power" subgroup was also noted. Results indicated a correlation between antagonistic patterns of ethnic relations and receptivity to racial propaganda and ideology. Further research focusing on the perceived ethnic relations climate is necessary to determine whether the patterns found in this institution are typical and to ascertain explanations for this correlation.

Adolescent↗
PubMed1978

Physostigmine: improvement of long-term memory processes in normal humans.

Nineteen normal male subjects received 1.0 milligram of physostigmine or 1.0 milligram of saline by a slow intravenous infusion on two nonconsecutive days. Physostigmine significantly enhanced storage of information into long-term memory. Retrieval of information from long-term memory was also improved. Short-term memory processes were not significantly altered by physostigmine.

Acetylcholine↗
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↗
PubMed1977

Narcolepsy, paranoid psychosis, and tardive dyskinesia: a pharmacological dilemma.

The case history of a 54-year-old man with concomitant narcolepsy, paranoid psychosis, and tardive dyskinesia is presented. These disorders may all result from alteration in catecholamines, serotonin, and/or acetylcholine in the central nervous system. The interactions of the various psychopharmacological agents usually used to treat the disorders when they occur separately are considered in terms of current neurotransmitter hypotheses. The management of this case creates a pharmacological dilemma; the agents used for treatment of each of the disorders separately exacerbate one or both of the other two syndromes.

Chlorpromazine↗
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↗
PubMedDate not supplied

ERPs to stimuli requiring response production and inhibition: effects of age, probability and visual noise.

Sixty-six normal adults ranging in age from 20 to 85 years were presented with stimuli containing explicit instructions to initiate or to inhibit a motor response (the words 'push' or 'wait'). In one task, the effect of stimulus probability was investigated by varying probability between 0.25 and 0.75 for both Go and No-go stimuli. In another task, the effect of visual noise was investigated by degrading the stimuli with ampersands on half of the trials. Regression analysis was used to examine the effects of age on P3 amplitude and latency for each stimulus type. The effects of stimulus variables on P3, independent of age, were examined by standardizing each subject's data to those expected for a 20 year old. P3 latency to all stimuli and RT to Go stimuli increased with age. The latency of P3s to No-go stimuli was less sensitive to age than Go stimuli. P3 amplitude at Cz and Pz (but not Fz) diminished with age. P3s to Go stimuli were maximal at Pz and earlier than P3s to No-go stimuli. P3s to No-go stimuli were maximal at Cz. These differences between Go and No-go stimuli remained true under visual noise and probability manipulations. Visual noise prolonged the latency of Go and No-go P3. Less probable Go and No-go stimuli elicited larger and later P3s than more probable stimuli. Decreasing the probability of the No-go stimulus enhanced its central distribution.

Adult↗
PubMedDate not supplied

Age-related decline in MRI volumes of temporal lobe gray matter but not hippocampus.

The effect of normal aging on the volume of the hippocampus and temporal cortex was assessed cross-sectionally with quantitative Magnetic Resonance Imaging (MRI) in 72 healthy men, spanning 5 decades of the adult age range (21 to 70 years). Neither the hippocampal nor cortical white matter volumes were significantly correlated with age. By contrast, left and right temporal lobe gray matter volumes, exclusive of the hippocampal measures, each decreased with age (p < 0.01). Volumes of temporal lobe sulcal CSF and the ventricular system (temporal horns and lateral and third ventricles) significantly increased with age. Measures of verbal and nonverbal working memory showed age-related declines and were related to enlargement of the three ventricular regions, which may be indicative of age-related atrophy of the adjacent cortex but not the hippocampus, at least up to age 70 years.

Adult↗