Shirley Y. Hill

Cocaine and morphine self-administration: Effects of differential rearing

Two groups of Wistar rats were reared in either enriched or impoverished conditions for 100 days postweaning. These two groups were further divided and tested for cocaine or morphine preference in a two-bottle choice (water alternative) for 16 days. Enriched and impoverished rearing has previously been found to alter emotionality, conditionability, and body weight of adult rats. Validating previous reports of differential rearing effects on body weight, the enriched animals in the present study weighed less than their litter mates reared in impoverished conditions. Animals reared in the enriched environment consumed significantly more cocaine than animals reared in an impoverished one. No significant differences were observed for morphine self-selection as a result of differential rearing.

Ethanol self-selection in rats: A distinction between absolute and 95 per cent ethanol

Abstract Preference-aversion functions for ethanol solutions prepared with absolute or 95 per cent ethanol were determined in normal, untreated rats. In a second experiment these functions were similarly determined except in this case, after 4 days of ad lib water, a second determination was made in which half the animals were intubated with saline and the others with p -chlorophenylalanine ( p CPA), a potent depletor of brain serotonin. In agreement with other studies, the intake of solutions prepared with absolute ethanol was markedly reduced by treatment with p CPA. In marked contrast to this finding, however, was the fact that this compound had little effect on preference-aversion functions for solutions prepared with 95 per cent ethanol. Ethanol intakes during saline intubations were not significantly lower than baseline levels for either group. The observed distinction between absolute and 95 per cent ethanol would seem to be particularly significant since it became apparent only during an experimental treatment and thus could be an important confounding variable in the self-selection study with animals.

Effect of food deprivation on hypothalamic self-stimulation in stimulus-bound eaters and non-eaters.

Abstract Previous studies concerned with the effects of food deprivation on hypothalamic self-stimulation were found wanting for lack of discrimination between feeding and nonfeeding sites. In the present study this omission was rectified which allowed the conclusion that food deprivation selectively potentiates the rewarding properties of hypothalamic stimulation at sites from which feeding can be elicited. The existence of a postdeprivation facilitation in both eaters and non-eaters reinforces the rationale for controlling this variable in studies designed to elucidate the neural substrates of consummatory behavior.

Effects of l-tryptophan and ethanol on sleep parameters in the rat

Sleep parameters were monitored following (1) a single 2 g/kg oral dose of ethanol, (2) an oral dose of l-tryptophan (600 mg/kg), and (3) administration of both drugs simultaneously. Ethanol reduced REM and increased slow wave significantly. The effects of l-tryptophan were apparent only in the case of one parameter, REM latency. Administration of both drugs resulted in a significantly shorter REM latency than that observed for ethanol administered alone. Results are discussed in terms of possible changes in the biosynthesis of 5-HT.

Cocaine effects on sleep parameters in the rat

Cocaine in 6 mg/kg doses was administered orally and intraperitoneally to rats and sleep EEGs recorded. Cocaine significantly reduced total sleep time, slow-wave sleep, and sleep latency. Rapid eye movement sleep (REM) was significantly suppressed during the first half of the sleep recording. These effects were evident by both routes of administration. The effects of cocaine on total sleep time in animals parallels that observed in man.

Critical Flicker Fusion: Objective Measure Of Alcohol Tolerance?

Studies dealing with the effects of alcohol on critical flicker fusion (CFF) are reviewed. The conclusion is drawn that relatively low doses of alcohol produce a decline in the flicker fusion threshold in normal subjects. Further, data are presented regarding the effects of alcohol on CFF in 32 male alcoholics. A decrement in the CFF threshold did not occur in alcoholic subjects given 8 to 10 ounces of vodka. This result suggests that CFF may be an objective measure of alcohol tolerance.

Effect of alcohol on "dissociated" learning in alcoholics.

A number of studies indicate that alcohol produces state-dependent effects in man. These studies are reviewed and evidence is presented that alcoholics are probably no more susceptible to state-dependent effects from alcohol than are nonalcoholics.

SHORT‐TERM MEMORY AND THE ALCOHOLIC BLACKOUT*

Sudden “insults” to cerebral functioning, such as occur in concussion and grand ma1 seizures, often produce memory loss that involves both retrograde and anterograde elements. The subject has varying degrees of amnesia for past experiences that have presumedly been “consolidated” and additionally has difficulty, for a time, storing new information. As a rule, the retrograde amnesia, if extensive in nature, over time undergoes “shrinkage”-that is, the period of amnesia becomes gradually reduced. However, the period during which the anterograde amnesia persists apparently involves an irreversible deficit in memory storage.’ Although the anterograde amnesia that occurs following concussions and seizures is usually transienf, it resembles the type of chronic, specific, shortterm memory impairment observed in patients with bilateral hippocampal lesions and in Korsakoffs syndrome.2 Another common form of amnesia occurs during alcohol intoxication. This amnesia, commonly called “blackout,” is rarely associated with other drug intoxications (scopalamine intoxication being one exception). Until recently, alcoholic blackouts had not been observed under experimental conditions, and it was unknown whether, like concussions and seizures, the amnesia comprised both retrograde and anterograde elements or was predominently one or the other in type. Nor was it known whether blackouts were a unitary phenomenon, based on common pathophysiological processes, or had various causes. Phenomenologically, blackouts range in severity from classic fuguelike states, in which the intoxicated individual performs highly complicated acts with little or no recollection of having performed them to spotty forms of memory loss in which discrete events are forgotten and, at least on some occasions, are recoverable spontaneously or by prompting. This has led to speculation that the former “en bloc” blackouts represent a failure of retention or consolidation whereas the more recoverable types of memory loss may reflect a phenomenon referred to as “statedependent” or “dissociated” learning.3 It is not the purpose of this paper to discuss the pros and cons for this argument. Instead, two questions relevant to alcoholic blackouts will be considered. First, evidence will be reviewed bearing on whether blackouts occurring in alcoholics are predominently retrograde or anterograde in nature. Second, data will be presented on whether alcoholic blackouts are graded or “threshold” phenomena.

Marihuana and critical flicker fusion. Evidence for perceptual sharpening.

Critical flicker fusion (CFF) has been used extensively in studying the physiology of vision. CFF refers to the minimal number of successive flashes of light per second that produces a sensation of steady light. The fusion threshold is affected by a variety of drugs having the capacity to alter central nervous system (CNS) excitability. The present study examines the effect of smoking 1g of marihuana containing 1.5 per cent (—)-Δ9- transtetrahydrocannabinol (THC) on the CFF threshold. Results of this study indicate that marihuana enhances the CFF threshold, unlike other drugs classified as CNS “depressants.” The increased excitability of the visual system following marihuana smoking is discussed with reference to previous reports of “perceptual sharpening.”

The Canter Background Interference Procedure (BIP): effects of demographic variables on diagnosis.

This paper reports a positive association between demographic variables and Canter BIP diagnostic classification. Ss are 209 middle-aged men and include psychiatric and medical patients and non-patients. To evaluate the joint effects of the demographic variables, a discriminate analysis was performed on the total sample. Race and educational level alone predicted BIP diagnosis in 67% of the cases. While none of the demographic variables was related significantly to BIP diagnosis when a discriminate analysis was performed on whites alone, age and educational level were related significantly to BIP diagnosis when a discriminate analysis was performed on blacks alone.