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Biomedical subjects

A Pfefferbaum

Publications and source records attributed to A Pfefferbaum.

At least 91 records · Page 5Linked to original sources
PubMed1980

Cholinomimetics and memory. The effect of choline chloride.

Young normal subjects received 16 g of choline chloride in a double-blind A-B-A design. Short- and long-term memory function was evaluated. Comparison of group means indicated that choline chloride did not significantly affect short-term memory or long-term memory. However, individual subjects may have had some aspects of long-term memory affected by choline chloride treatments. The results suggest that the effect of lower doses of choline on long-term memory should be evaluated.

Adolescent↗
PubMed1980

beta-Endorphin and schizophrenia.

To study the effects of beta-endorphin in chronic schizophrenia, nine male patients participated in a double-blind crossover comparison of a single intravenous 20-mg injection of beta-endorphin and saline. Bolus injection of beta-endorphin from an albumin-coated syringe produced markedly higher plasma concentrations than did slow intravenous infusion from a non-albumin-coated syringe. Beta-endorphin intravenously injected in nine patients produced a statistically significant increase in serum prolactin levels. In one patient, both 10 mg of morphine sulfate and 20 mg of beta-endorphin produced similar increases in the alpha power of the EEG. In eight patients, beta-endorphin administration was associated with a statistically significant but not clinically obvious improvement in schizophrenic symptoms.

Adult↗
PubMed1980

Age differences in P3-reaction time associations.

Eight healthy old and 12 healthy young women had event-related potentials (ERPs) recorded during the performance of a memory retrieval task. For each subject the single trial data recorded at Pz were analyzed using Woody's adaptive filter technique. The old subjects differed from the young in several respects: P3 amplitude at Pz was smaller, P3 latency and reaction time (RT) were greater, the relationship between P3 latency and RT was considerably altered. The adaptive filter increased the amplitude of P3 but the age-related amplitude difference persisted, suggesting that this difference is not due to increased latency variability with age. The old subjects had lower single trial P3-RT correlations and longer elapsed time from P3 peak to the response than did the young subjects. Both groups had greater RTs for outset items ('negative' responses) than for inset items ('positive' responses). For the young subjects P3 latency was also greater for the outset compared to the inset items but the difference was not found for the old subjects. Thus, the relationship between P3 latency and RT is altered in the aged--P3 and RT are less tightly coupled than in the young.

Adult↗
PubMed1980

Age-related changes in auditory event-related potentials.

Twelve elderly and 12 young women were subjects in a reaction-time task designed to elicit middle and late event-related potentials (ERP). The aged subjects differed from the young in respect to the later occurring ERP components: P2 was larger and later; P3 was later and had a different scalp distribution; the slow wave (SW) was smaller. In contrast, no age-related differences were found for N1 amplitude or latency. It is suggested that the diminution in SW amplitude contributes to the change in scalp distribution of P3 amplitude seen with age. The relationship of reaction time and P3 latency of single trials was examined by the adaptive filter technique. There was no difference between the old and young subjects as both groups revealed signficant, positive P3 latency-reaction time correlations.

Adult↗
PubMed1980

Event-related potentials in schizophrenics.

Fifteen schizophrenics and 15 age-matched controls were compared on 3 auditory event-related potential (ERP) paradigms that elicited a variety of components. In one paradigm, tones were given at 0.75, 2.25 and 6.75 sec interstimulus intervals; in another, infrequently occurring targets in a reaction-time task were interspersed with frequent background stimuli; and, in a third, noise bursts or tones were delivered in a random sequence at either 70 or 100 dB SPL. The sensitivity of some of the ERP components in distinguishing schizophrenics from controls depended on the conditions under which the component was elicited. N1 amplitude was smaller in the schizophrenics than in the controls after longer interstimulus intervals. P2 amplitude was smaller in the schizophrenics than in the controls after longer interstimulus intervals. P2 amplitude was smaller in the schizophrenics only at higher stimulus intensities. P2 latency was shorter in schizophrenics except in the paradigm that varied interstimulus intervals. P3 amplitude, however, was much smaller in schizophrenics than controls ragardless of whether P3 was elicited by targets in a task or was elicited by 100 dB SPL stimuli. The loud stimuli also elicited blink reflexes that coincided with N1, but these reflexes did not vary by clinical group. Neither the amplitude of the slow wave following targets nor the sustained potential that accompanies prolonged auditory stimuli differed between schizophrenics and controls.

Adult↗
PubMed1980

P3 reduction in auditory evoked potentials of schizophrenics.

Fifteen schizophrenics and 15 age-matched controls performed a reaction time (RT) task. A Bernoulli sequence of 85 dB SPL, 50 msec, 800 c/sec (P = 0.85) and 1200 c/sec (P = 0.15) tones was presented with an interstimulus interval of 1 sec. Subjects were instructed to press a button quickly upon hearing the 1200 c/sec tone. If a subject failed to respond within 650 msec, a 50 msec white noise burst occurred. In averages synchronized with target tones and computed without respect to RT, P3 was maximal at PZ with a mean latency of 330 msec for both schizophrenics and controls. P3 amplitude at PZ, however, averaged 6 muV in schizophrenics and 14 muV in controls (P < 0.001). Both mean RT and mean within-subject variance were greater in schizophrenices than controls. Other kinds of averages were computed to investigate the possibility that the amplitude differences were associated with different RTs or with differences in P3 latency variability in underlying trails. Averages of trials associated with short RTs (100--286 msec) had larger P3s than averages associated with long RTs (287--600 msec) (P < 0.01). Within each RT range, however, schizophrenic P3s were smaller than control P3s. Neither response-synchronized averaging nor adaptive filtering eliminated P3 amplitude differences between groups, indicating that P3 latency variability cannot account for these differences. We hypothesize that the smaller P3s in schizophrenics represent a deficit in reactivity to unexpected stimuli that is compatible with normal RT performance.

Adult↗
PubMed1980

Auditory brain stem and cortical evoked potentials in schizophrenia.

Auditory brain stem and cortical evoked potentials were recorded from 15 schizophrenics and 15 controls. There were significant cortical evoked potential differences between the two groups. However, brain stem evoked potentials were almost identical, suggesting that the cortical evoked potential differences are not due to peripheral factors such as inability to match sensory thresholds or defects in auditory acuity.

Adult↗
PubMed1979

EEG effects of physostigmine and choline chloride in humans.

Seventeen normal volunteers received either 0.5 mg, 1.5 mg, or 2.5 mg physostigmine i.v. in a placebo-drug-placebo single-blind design. EEG was recorded simultaneously and analyzed by computerized spectral analysis. Eleven healthy elderly volunteers (mean age = 69.1 years) with mild memory impairment were treated with placebo, followed by oral choline chloride (either 8 g/day for 3 weeks, or 16 g/day for 1 week), and then, again, placebo. Recordings of spontaneous EEG and EEG event-related potentials (contingent negative variation) were obtained during both placebo and choline treatments. The larger doses of physostigmine produced an increase in low frequency activity and a slowing of the peak alpha frequency. Oral choline chloride had no effect on the EEG as measured by spectral analysis, but appears to have differential effects on contingent negative variation (CNV) amplitude and reaction time, depending upon the initial CNV amplitude.

Adult↗
PubMed1979

Event-related potential changes in healthy aged females.

Neurophysiological changes in the central nervous system were demonstrated with EEG even-related potentials in healthy, aged women. Compared to young women, the aged women showed decreased amplitude of the late sustained potential (SP), increased P2 latency, disruption of the normal stimulus intensity-response amplitude function of P2 and increased amplitude of the P1 component. These age-related changes are interpreted as neurophysiological reflections of CNS deterioration found in non-senile elderly persons.

Adult↗
PubMed1979

Event-related potential changes in chronic alcoholics.

Ten chronic alcoholics (10+ year alcoholic drinking history) and ten age and sex matched controls were tested on an ERP paradigm which elicited a large P3 component. The N1 and P2 sensory evoked potential components did not differ in amplitude or latency between the two groups. The latency of the P3 was significantly longer for the alcoholics than the controls for both a response and non-response stimulus. This finding is consistent with the results seen in a variety of dementias and is offered as evidence of the dementing effects of prolonged alcoholism in this group of subjects. While the P3 latencies were prolonged for the alcoholics, their reaction times were not different from the controls. Single trial analysis using Woody's adaptive filter also demonstrated that the single trial estimates for the 3 latency were significantly prolonged for the alcoholics. The single trial correlation between the P3 latency and each trial's corresponding reaction time was significantly greater for the alcoholics than for the controls.

Acoustic Stimulation↗
PubMed1979

Human EEG response to beta-endorphin.

Beta-endorphin, morphine, and saline were given intravenously to a single schizophrenic subject on separate occasions in a double-blind design. EEG spectral analyses performed on data collected before and after drug injection demonstrated that beta-endorphin and morphine produced similar increases in alpha power within 5 to 15 minutes after injection. This effect could be distinguished from two placebo (saline) injections. These data suggest that intravenous beta-endorphin can produce changes in the central nervous system in humans.

Adult↗
PubMed1979

The effects of ethanol and meperidine on auditory evoked potentials.

The effects of ethanol and meperidine on the auditory evoked potential (AEP) to stimuli of different intensities were investigated. Sixteen normal male volunteers received ethanol, 0.8 ml/kg, 100 mg meperidine, and a placebo on different days in a double-blind study. AEPs were recorded from Fz, Cz and Pz electrode placements. The stimuli were 500 msec 1000 Hz tones at 50, 60, 70 and 80 dB sound pressure level presented in a pseudo-random sequence. Meperidine had no significant effect on AEP variables. Ethanol reduced AEP activity between 24 and 250 msec but had no effect on the sustained potential measured between 300 and 450 msec.

Adult↗