Richard H. Carlson

The effects of ethanol upon threshold and response rate for self-stimulation.

The hypothesis that ethanol would reduce the threshold for self-stimulation of the medial forebrain bundle was not supported. Ten rats, implanted with electrodes in the lateral hypothalamus, were shaped to bar press for electrical brain stimulation. The effects of 0.6, 0.9, and 1.2 g/kg ethanol injections upon threshold and response rate for self-stimulation were measured. The lowest dose had no effect upon self-stimulation threshold while 0.9 and 1.2 g/kg ethanol raised thresholds. Rate of bar pressing was increased by 0.6 g/kg ethanol but was not affected by higher dose. Results were discussed in terms of a postulated dual effect of ethanol upon a brain arousal system and upon a reward system.

The role of locomotion in conditioning methylphenidate-induced locomotor activity.

This experiment determined whether overt performance of the entire response (actual running) was necessary for the conditioning of methylphenidate-induced locomotor activity (wheel-running) in guinea pigs. Four guinea pigs were given daily injections of 2.5 mg/kg methylphenidate and were allowed to run in activity wheels; 4 other guinea pigs were given methylphenidate and were placed in locked activity wheels; a third group of 4 guinea pigs were administered saline and allowed to locomote; a fourth group of 4 guinea pigs received saline injections and were placed in locked activity wheels. After 12 days of injection, all animals were given saline injections on the 9 subsequent days and allowed to run freely in the wheels. The 2 groups which had received methylphenidate showed more locomotor activity than the saline injected animals but were not distinguishable from each other on the basis of prior opportunity to engage in locomotor activity. These results were interpreted to indicate that (a) increased methylphenidate-induced locomotor activity may be conditioned with repeated administration of the drug, and (b) actual running is not essential for the conditioning of drug-induced wheel-running.

Early handling and maternal behavior: Effect on d-amphetamine responsiveness in rats

Abstract This study determined whether early handling and maternal behavior could influence the behavioral changes associated with chronic amphetamine administration. In Experiment 1, seven litters received early handling (rat pups were removed from the nest for 3 min daily during the first week following parturition) and 7 litters were undisturbed. At 105 days of age, male animals from non-handled litters showed a decline in rearings induced by 2.0 mg/kg d-amphetamine across 12 test days in a Y-maze but handled animals showed no such pattern. Handling had no effect on entries. In Experiment 2, four litters were handled and returned to a mother-present nest (H), 4 litters were handled and returned to a mother-absent nest 1 hr prior to reunion with the rat mother (HMS), 4 litters were separated from mothers for 1 hr (MS), and 4 litters were undisturbed (C). At 55 days of age, a handling (Groups H and HMS) effect on open-field activity was observed. At 75 days of age, male animals were injected with 0.0, 2.5 or 10.0 mg/kg d-amphetamine and tested in a Y-maze. At 2.5 mg/kg handled animals, whether maternally separated or not (H and HMS) showed no decline in drug-induced rearings; maternally separated animals whether handled or not (MS and HMS) showed fewer entries and increased body weight. However, only animals at 2.5 mg/kg from handled, mother-present litters (H) showed a retarded increase in stereotypy across 8 test days. These results indicated that behavioral manipulations early in life may influence responsiveness to d-amphetamine in adulthood, either directly or through associated changes in maternal behavior.

Evidence for color vision in the prairie dog (Cynomys ludovicianus)

An experiment was performed to determine whether prairie dogs could use color information. By means of a WGTA four prairie dogs (Cynomys ludovicianus) were presented with two-choice color discrimination problems. Criterion for learning was set at 90% correct responses. Results indicate that some discriminations were learned more quickly than others, but criterion was reached on all possible combinations of red, yellow, blue, and green hues when brightness was irrelevant, indicating good color vision for this species.

Habituation of Electrically Induced Readiness to Gnaw

Electrical stimulation of the hypothalamus in prairie dogs (Cynomys ludovicianus) produced a readiness to gnaw which decreased over time, exhibited spontaneous recovery, and could be dishabituated by foot shock. The response decrement was in part habituatory and could modify the interaction between a stimulation-induced readiness to gnaw and a physiologically induced hunger. Functional plasticity of stimulation-induced behavior might be accounted for, in part, by habituation.

Effects of prior experience and 'functional disturbance' on acute and chronic tolerance to methylphenidate.

The degree of habituation or adaptation an animal has experienced prior to the administration of methylphenidate was found to be more crucial in determining the animals response to the drug than chronic drug administration alone. Rats allowed to adapt in a Y-maze for 24 days showed less methylphenidate-induced activity than animals receiving chronic administration of saline or methylphenidate but no adaptation, when animals were injected with the drug and tested in the Y-maze on Day 25. Animals also were shown to develop tolerance to the methylphenidate-induced activity.

Tolerance in methylphenidate-induced locomotion in prairie dogs (cynomys ludovicianus)

After a five-day adaptation period in activity wheels, four prairie dogs were assigned to a methylphenidate group (2.5 mg/kg, s.c.) and four prairie dogs were assigned to a saline group for ten consecutive daily injections. Half-revolutions of locomotor activity were recorded during seven measurement periods taken daily. During the third measurement period, from 1–3 hrs following injection, the methylphenidate group declined in locomotor activity over the first three days of drug administration.

Successive Spatial Discrimination Reversals in the Prairie Dog

Six prairie dogs (Cynomys ludovicianus) were given reversal training on a spatial discrimination reversal task in a Wisconsin General Test Apparatus (WGTA). As with many other species, more errors occurred on the first reversal problem than during acquisition of the original discrimination. However, performance improved over training until each S eventually reversed after a single nonreinforced error. Initial findings indicate that prairie dogs perform at high levels in discrimination learning experiments and could be valuable subjects for psychological research.

EFFECTS OF HEALTH LOCUS OF CONTROL AND HEALTH VALUE UPON EMG BIOFEEDBACK TRAINING

Subjects who scored highly internal or external on a health locus of control scale and who scored high or low on the value each attached to good health were each given two sessions of frontalis EMG biofeedback training in accordance with a 2 × 2 × 2 factorial design. It was predicted that both internality and high health value would be positively associated with ability to control EMG and that these influences would combine additively. The predictions were not supported but a significant interaction between internality and health value was found. This interaction could be explained by assuming that both internality and high health value increased drive which in turn produced greater muscle tension, the relationship between drive and muscle tension being an ascending sigmoid function.

A Guide to Psychiatric Drugs

The pastoral counselor often finds himself in the position of working with people who are also under the care of a psychiatrist or a general practitioner who has prescribed medication. At other times, he may work with people who are using unsupervised medication. As a result, it is important for him to understand the basic effectsof the psychoactive drugs used in medical practice. He needs to know not only the beneficial effectsof the drugs but also the side effects which usually accrue. Since the early 1950s, more and more psychoactive drugs have come into use, and the minister may encounter a large array ofthese agents. It is certainly not necessary that he fully understand the biochemical mechanisms underlying the actions of these drugs, but it is often helpful for him to be acquainted with their basic effects. Considering the number of psychoactive drugs being used at the present time, even this can be a formidable task. Information from the physician concerning drugs taken by the patient can be very helpful; however, the minister may need other resources to draw upon. This article is intended to be a brief overview of the major classes of drugs now being used to treat emotional and behavioral difficulties.