Alexander J. Rosen

Introversion, attention and the late positive component of event-related potentials

Variation in P3 amplitude across normal individuals under the same experimental conditions has been routinely observed. The possibility that such variation reflects individual differences in the allocation of attention was examined by comparing P3 amplitude in introverts and extraverts, who are thought to differ in the allocation of attention during monotonous tasks. Event-related potentials were recorded while the subjects participated in a lengthy stimulus prediction task. P3 amplitude was determined by principal components analysis and it was found to be significantly larger for the introverts than for the extraverts. This finding is interpreted as evidence that P3 amplitude is sensitive to individual differences in the allocation of attention.

Controlled examination of effects of progressive relaxation training on seizure reduction.

Summary: We determined the efficacy of progressive muscle relaxation in reducing seizure frequency. Subjects were 24 people with epilepsy attending an urban neurology clinic. The experimental design consisted of an 8‐week baseline period, a treatment period of six sessions of progressive relaxation training (PRT, n = 13) or quiet sitting (QS, n = 11) and an 8‐week follow up. In the PRT group, 11 subjects reported a decrease in seizure frequency (p < 0.01), and in the QS group, 7 reported a decrease (p > 0.05). The mean decrease in seizure frequency was 29% for the PRT group (p < 0.01) but only 3% for the QS group (p > 0.05). This is the fifth recent report of a controlled study documenting the success of progressive relaxation therapy in seizure reduction. PRT is inexpensive and noninvasive and facilitates patient participation. Such a technique should be incorporated into clinical practice.

The effects of amobarbital sodium on differential instrumental conditioning and subsequent extinction

SummaryTwenty-four rats received 54 differential instrumental conditioning trials (single stimulus presentation) in which an approach to one stimulus was reinforced and to a second was nonreinforced, followed by 24 extinction trials in which approaches to either were nonreinforced. Twelve animals received a 20 mg/kg amobarbital sodium injection (i. p.) ten minutes before the six daily trials and 12 received an equal volume isotonic saline injection. The drug did not affect terminal response latency to the reinforced stimulus but resulted in shorter latencies to the nonreinforced stimulus in both initial acquisition and extinction. These data support the hypothesis that amobarbital at this dose level has a specific attenuating effect on those anticipatory processes related to aversive emotion-producing events.

Adrenocortical influences upon the extinction of an appetitive runway response

Abstract Sprague-Dawley rats received daily injections of either ACTH, hydrocortisone, corticosterone, or placebo throughout the acquisition and extinction of a food-reinforced runway response. The results showed that hormone injections produced no systematic effects upon acquisition performance. Injections of either hydrocortisone or corticosterone, however, produced faster running on early extinction trials as compared to either ACTH or placebo injection. There was some suggestion that increased corticosteroid levels, rather than some change in ACTH levels, produced the effects upon extinction responding.

Behavioral assessment of psychiatric inpatients and normal controls across different environmental contexts

Objectively defined, publicly observable behaviors were time sampled for hospitalized psychiatric patients and normal controls in three distinct environmental contexts: lunch time, free time, and gym time. The behaviors sampled included body activity, extremity activity, proximity, social interactions, participation, visual scanning, laughing/smiling, and idiosyncratic behavior. Patient behaviors were recorded during both a drug-free baseline period and a subsequent medication period. The data suggest that consistent and reliable differences between patients and normals in most behaviors can be observed and that environmental context is an important determinant of these differences. Results are discussed in terms of their implications for assessment procedures and treatment decisions.

The effects of psychotropic drugs on the double alley frustration effect

SummaryCentral nervous system stimulants (amphetamine, methylphenidate), depressants (sodium amobarbital, reserpine, tetrabenezine, chlorpromazine) and anti-depressants (iproniazid, pargyline) were administered intraperitoneally to rats prior to their daily trials in an Amsel double runway in an attempt to modify the frustration effect using within-subject comparisons. Absolute running speeds following reinforcement and nonreinforcement were markedly affected by the drugs. However, in contradistinction to conditioned frustration which has proven amenable to pharmacological intervention, the primary frustration in the present paradigm, involving a response that immediately follows nonreward, proved highly resistant to modification.

Effects of lysergic acid diethylamide on simple instrumental conditioning, extinction and discrimination learning in the rat☆

Abstract Hungry rats were trained under placebo or LSD (high and low dose) conditions to either run in a straight alley for food or lever press (FR20) in a Skinner box in the presence of one of two spatially positioned bars associated with food reward. A testing phase followed in which animals continued to perform under either the same injection conditions or under one of the alternative injection conditions. The results indicated that high drug doses (0.20 mg/kg) increased resistance to extinction in the runway but impaired both running acquisition and discrimination whereas low doses (0.05 mg/kg) impaired running but improved discrimination. There were some indications that LSD had long-term behavioral consequences which outlasted the drugged state, suggesting an effect on learning as well as on performance.

Pharmacotherapy of schizophrenia and affective disorders: Behavioral assessment of psychiatric medications

Objectively defined, publicly observable ward behaviors (body activity, extremity activity, scanning, social interaction, proximity, participation, laughing/smiling, and idiosyncratic behavior) emitted by psychiatric inpatients with either schizophrenic or affective disorders were time sampled both before and during the administration of psychiatric medications (neuroleptics, tricyclics, and lithium). The data indicate that the primary effects of the pharmacological interventions are confined to activity measures and symptoms rather than social behaviors. The implications of these results for treatment protocols are discussed in terms of interactions between pharmacological and psychosocial interventions. In addition, rates of behavior during treatment were related to baseline rates via a log-log function of negative slope, a result that is consistent with data derived from the infrahuman laboratories. Taken together the results provide support for attempts to relate preclinical and clinical psychopharmacology and suggest that behavioral assessment can be applied profitably to drug effects in clinical situations.

The Effects of Neuroleptic Drugs on the Social Interactions of Hospitalized Psychotic Patients

The frequency of social interactions emitted by two groups of hospitalized psychotic patients was studied with a time sampling procedure during lunch periods in the ward dayroom. One group was treated with neuroleptic medication upon admission to the ward, and the other group was medicated after a 2− to 3-week washout period. The data suggest that the principle effect of the medication is to produce a transient depression in social interaction frequency which returns to baseline with continued drug treatment. The results are supportive of previous research which indicated that the major impact of pharmacotherapy is on activity rather than social behaviors, and highlights the utility of including baseline measures to ensure adequate drug vs. control comparisons.

Effects of metamphetamine, pipradrol and methylphenidate on instrumental conditioning and spontaneous motor activity in the immature rat

Ip injections of methamphetamine (0.5 and 2.0 mg/kg), pipradrol (2.0 and 5.0 mg/kg), and methylphenidate (2.0 and 5.0 mg/kg) impaired the acquisition and performance of a simple alternation light-on-light-off instrumental response in weanling rats. High drug doses drastically reduced differential response (DR) rates and markedly elevated spontaneous motor activity (SMA). Low drug doses depressed DR asymptotes and slightly increased SMA. These findings with young rats are comparable to those with adult rats and question the usefulness of the immature rat as a model for the effects of stimulants in children.