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Biomedical subjects

L O Bauer

Publications and source records attributed to L O Bauer.

At least 55 records · Page 3Linked to original sources
PubMed1994

Electroencephalographic and autonomic predictors of relapse in alcohol-dependent patients.

Measures of electroencephalographic and autonomic activity were recorded from 17 alcohol-dependent patients (after 7-10 and 14-17 days of abstinence) and 14 age-matched non-drug-dependent controls (after comparable intervals). The alcohol-dependent group was divided into subgroups of abstinence-prone or relapse-prone patients, based on their 3-month posttreatment outcome. Data analyses revealed that relapse-prone patients evidenced more electroencephalographic beta-activity at the vertex lead, and a larger amplitude carotid pulse than abstinence-prone patients and controls. The implications of these preliminary findings for relapse prediction and typological development are discussed.

Adult↗
PubMed1994

Frontal P300 decrements in antisocial personality disorder.

Event-related potentials (ERPs) were recorded from 83, 21- to 25-year-old nonalcoholic men varying in alcoholism vulnerability due to the presence/absence of an alcoholic family history or a personal history of antisocial personality disorder. ERPs were elicited by a visual oddball task in which the target was presented more frequently than the nontarget, in order to elicit impulsive or perseverative responding. Analyses of N200 and P300 revealed no group differences in the nontarget response. However, analyses of the target response revealed a significantly smaller P300 in the antisocial personality (ASP)+ group compared with the ASP- groups. The P300 decrement was limited to frontal electrode sites and is interpreted as indicating the presence of subtle anterior brain dysfunction among ASP+ subjects.

Adult↗
PubMed1993

Motoric signs of CNS dysfunction associated with alcohol and cocaine withdrawal.

Measures of hand tremor and body sway were recorded from 6 alcohol-dependent (AD) and 16 cocaine-dependent (CD) patients after 1, 3, and 12 weeks of verified abstinence. The same measures were recorded from 15 nonpatient control subjects after comparable intervals. Hand tremor was transduced via an accelerometer. Body sway was transduced by a force-sensitive platform. Analyses revealed different patterns of motoric dysfunction in the AD and CD groups. AD patients exhibited enhanced hand tremor during a pointing task and enhanced body sway. Both of these abnormalities remitted with continued abstinence. CD patients exhibited enhanced and unchanging levels of resting tremor across the first 12 weeks of abstinence, but they had normal levels of body sway and action tremor. These results are interpreted as reflecting a subclinical cerebellar dysfunction in recovering AD patients, and a subclinical extrapyramidal dysfunction in the CD counterparts.

Adult↗
PubMed1993

Reaction time during cocaine versus alcohol withdrawal: longitudinal measures of visual and auditory suppression.

Visual and auditory stimulus discrimination tasks, analogous to those used in the Reitan-Klove Sensory Perceptual Examination, were performed by 12 cocaine-dependent and 5 alcohol-dependent patients after 1 week, 3 weeks, and 3 months of verified abstinence. Sixteen control subjects, who were not substance-dependent, performed the same tasks after comparable intervals. During each task, either visual or auditory stimuli were presented in the left, in the right, or in both sensory fields. A simple key press was made to discriminate these conditions. Cocaine-dependent patients responded more slowly than control subjects during both tasks. The reaction-time slowing persisted across all three sessions, spanning a 3-month period of abstinence. There were no significant differences between the cocaine-dependent and control groups in response accuracy. In the context of other findings, these findings are interpreted as reflecting an enduring effect of prior cocaine dependence on motor as opposed to sensory functioning.

Acoustic Stimulation↗
PubMed1993

EEG, autonomic and subjective correlates of the risk for alcoholism.

Electroencephalographic, autonomic and subjective reactions to alcohol were examined among 78 young nonalcoholic men, cross-classified with respect to the presence/absence of a family history of alcoholism (FH) and the presence/absence of a personal history of antisocial personality disorder (ASP). Both an alcohol placebo and alcohol (0.32 ml/kg) were administered in a single laboratory session. The four groups of subjects were compared at baseline, and at several discrete time points before and after consumption of placebo and alcoholic beverages. During the baseline period, ASP+ subjects exhibited significantly more body sway and faster frontal EEG activity than their ASP- counterparts. The combination of ASP with FH was associated, at baseline, with an excessive amount of high frequency (18.6-27.6 Hz) beta activity in the right frontal EEG. After beverage consumption, several significant FH effects emerged that were independent of the effects of ASP. After placebo consumption, FH+ subjects exhibited significantly more fast alpha (10.9-12.5 Hz) activity at the right frontal electrode than FH- subjects. This difference persisted until blood alcohol concentrations began to rise, at which time fast alpha activity in FH+ subjects declined to FH- levels. Differences between the two FH groups were also apparent in their subjective reactions to the placebo and alcoholic beverages. Relative to FH- subjects, FH+ subjects rated themselves as more intoxicated after consuming the placebo but less intoxicated after consuming alcohol. FH+ subjects expressed greater confidence in their ability to resist the offer of an alcoholic drink across most time points.

Adult↗
PubMed1992

Effect of task difficulty and interstimulus interval on blink parameters.

The effects of task difficulty and interstimulus interval (ISI) on blink rate, blink latency and blink duration, were studied in a modified Sternberg memory task in which either two or six characters were to be memorized. Stimuli were presented in ISI blocks at either 5.3 or 9.3 s (SOAs of 6 or 10 s). While blink rate and blink duration declined prior to each stimulus, the difficulty of the expected task (the length of the memory set) did not affect the rate of decline or the final prestimulus level. Concerning ISI, blink rate declined more rapidly during shorter ISIs but the final prestimulus level, as was the case with task difficulty, was unaffected by the ISI duration. Presentation of the 6-character memory set produced a marked immediate inhibition of blinking. The data suggest that the encoding of visual stimuli is more akin to processes invoked in preparation for input than to ensuing processing stages since both encoding as well as preparation are accompanied by inhibition of blinking.

Adolescent↗
PubMed1992

Bromocriptine and cocaine cue reactivity in cocaine-dependent patients.

Based on previous reports that bromocriptine, a postsynaptic dopamine agonist, reduced cocaine craving and prevented relapse in cocaine-dependent subjects, effects of the drug were evaluated in 20 cocaine-dependent males in an inpatient drug rehabilitation programme. The subjective and physiologic effects of exposure to both cocaine-associated and neutral stimuli, presented using videotapes, were measured at one-week intervals. Between laboratory sessions subjects received either bromocriptine (1.25 mg bid) or a matched placebo, administered in double-blind fashion. Compared with the neutral videotape, the cocaine videotape elicited both a greater desire to use cocaine and more symptoms associated with cocaine self-administration. These results support an appetitive conditioning model of cocaine effects. Bromocriptine, however, had no effect on the cocaine-cue-associated reactivity, which declined over the 1-week interval in both treatment groups. Methodological differences among studies that have examined the effects of bromocriptine in cocaine-dependent subjects may explain the variable findings observed.

Adolescent↗
PubMed1991

Neuroendocrine responses in alcoholics to the presentation and consumption of a perceived alcoholic beverage.

Eight male alcoholic inpatients in their 2nd week of treatment were presented with, and instructed to consume, a beverage described at one session as containing alcohol and at another as not containing alcohol. The beverage on each occasion did not, in fact, contain alcohol. The results indicated that when subjects believed they had consumed alcohol, the change in insulin from baseline was significantly greater at 10, 20, and 30 min following consumption. The findings suggest that the insulin response of alcoholics following ingestion of a carbohydrate-containing beverage is enhanced by the anticipation of ethanol.

Alcohol Drinking↗
PubMed1991

Neuropsychological factors in individuals at high risk for alcoholism.

It has been postulated that deficits in certain areas of cognitive functioning among children of alcoholics may contribute to their increased risk for developing alcoholism and other substance abuse disorders. In this chapter, the recent evidence for this hypothesis is critically reviewed. Studies citing differences in cognitive functioning between persons at high risk versus those at low risk for alcoholism are presented as well as those studies that have failed to demonstrate differences in cognitive abilities. On balance, the evidence in support of variations in cognitive abilities at risk factors for the development of alcoholism is not strong. The equivocal nature of the literature may be due to a variety of issues related to the design of studies examining risk factors for alcoholism, to the variability of definitions of family history positive used, to the failure to adequately control potentially confounding subject variables, and to the improper analysis of data. Recommendations are made for future studies examining neuropsychological functioning in "at risk" samples.

Adolescent↗
PubMed1990

Precortical filtering and selective attention: an evoked potential analysis.

Attention-related changes in the human auditory brainstem response and the short-latency somatosensory evoked potential (SLSEP) were demonstrated in separate experiments. In Experiment 1, ABRs were recorded during conditions in which subjects awaited the presentation of either auditory or somatosensory target stimuli. In Experiment 2, median nerve SLSEPs were recorded in a similar task context. Analyses of ABR and SLSEP component amplitudes and latencies revealed that the auditory nerve (wave II) and rostral brainstem (wave V) components of the ABR, and the cervical component (N12) of the SLSEP, were facilitated when attention was directed toward stimuli that were presented in the same sensory modality and receptive field as the EP-eliciting stimuli. These results suggest that central mechanisms can modulate the transmission of auditory and somatosensory information at an early, precortical stage and that these mechanisms play a role in auditory and somatosensory selective attention.

Adult↗
PubMed1983

Effects of two doses of methylphenidate on cross-situational and borderline hyperactive children's evoked potentials.

This study involved 27 children displaying cross-situational hyperactivity and 14 youngsters with borderline hyperactivity. For all patients, evoked potentials were recorded after receiving 0 (placebo), 0.3 and 0.6 mg/kg methylphenidate. Under each pharmacologic condition, subjects were administered: a photic stimulation procedure; two versions of the Continuous Performance Test (CPT), which varied in difficulty level; and a discrimination ('oddball') test. Under photic stimulation, methylphenidate reduced the impact of increasing brightness levels on the rates of amplitude increment and latency decrease in the P208 component of the visual evoked response. These results are similar to those obtained by Buchsbaum and Wender (1973) for hyperactive patients with a positive clinical response to amphetamine. In CPT and the discrimination test, the two active dosages of methylphenidate brought about a comparable reduction of placebo levels of errors and reaction time. Analogously, in both versions of CPT, the two active dosages resulted in comparable increases in the amplitude of two components of the late positive complex (LPC; P510 and P740). P510 was identified as a classical P300. In the discrimination test, the effect of the stimulant on the response evoked by the visual non-target was to increase the amplitude of a component (P463) previously identified as P300. These pharmacologic results were nearly identical for borderline and cross-situational patients. In general, the results confirmed previous observations that methylphenidate improves hyperactive children's performance and increases the amplitude of their LPC. Further, these findings support previous observations that hyperactive patients' cognitive processing is optimized by a dosage of 0.3 mg/kg methylphenidate. Finally, the similarity between findings for cross-situational and borderline hyperactive patients is consistent with other evidence that stimulant effects are not limited to classically hyperactive children.

Attention Deficit Disorder with Hyperactivity↗
PubMed1981

Effect of methylphenidate on young adult's vigilance and event-related potentials.

Two studies were conducted on the effects of methylphenidate (20 mg) on young adults' event-related potentials. Although this stimulant elevated heart rate in study 1 (n = 14), it failed to affect either performance or amplitude of the late positive component (LPC) obtained from two versions of the continuous performance test (CPT). Because performance on these tasks was nearly error-free, we conducted study 2 (n = 23) to test the hypothesis that methylphenidate enlarges LPC amplitude only in more challenging tests than those used in study 1. In study 2, although heart rate was again elevated by the 20 mg dose of methylphenidate, LPC amplitude and performance were again unaffected in the two tasks employed in study 1 or in an easy tone discrimination procedure. However, in a more difficult version of CPT (10% errors of omission), both accuracy and amplitude of the concurrently obtained LPC were increased by methylphenidate. Similarly, in a choice-reaction time test, the stimulant increased speed as well as CNV amplitude. Our interpretation of the results is based on the view that LPC reflects the number of attentional resources committed to a stimulus during the evaluation stage. Thus, increases in LPC amplitude by methylphenidate are obtained only in tasks in which the subject may profit from the recruitment of additional attentional resources.

Adult↗
PubMedDate not supplied

Hemispheric differences for P300 amplitude from an auditory oddball task.

The P3(00) event-related potential (ERP) was elicited in 80 normal, right-handed male subjects using a simple auditory stimulus discrimination task, with electroencephalographic (EEG) activity recorded at 19 electrodes. P300 amplitude was larger over the right compared to left hemisphere electrode sites primarily at anterior-medial locations (F3/4, C3/4) for both target and standard stimuli. The N100, P200, and N200 components also demonstrated several similar, albeit less robust, hemispheric asymmetries. No hemispheric effects for P300 latency were observed, with few consistent latency findings for any of the other components obtained. The results suggest that the discrimination process underlying P300 generation may originate with right frontal activation.

Acoustic Stimulation↗