Sodium Amytal and Eyelid Conditioning

Abstract

Sodium amytal has long been regarded as a physiologically inhibiting drug. It is widely used in clinical practice as a sedative and sleep-producing drug, although all of its precise pharmacological effects are not definitely established. It has also been suggested that sodium amytal produces an increase in extra-version, as manifest by an increase in communicativeness, etc. Thus Lindemann (1932) found that after receiving amytal, normal subjects report feeling of increased well-being, co-operativeness, serenity and friendship. Sodium amytal is also used for the reduction of manifest anxiety. Sargant and Slater (1954) cite many examples of its use for this purpose with neurotic subjects; they describe it as useful for “deconditioning to situations likely to produce anxiety”. Masserman (1938) reports that amytal apparently reduces the sympathetic activity in cats which normally results from faradic stimulation from the hypothalamus. It has also been shown to abolish conditioned fear responses in kittens (Bailey and Miller, 1952).The literature related to conditioning is enormous. Hilgard and Marquis (1940) alone have a 973 item reference list at the end of their book. It has been established that anxiety neurotics or anxious subjects condition better than normals (e.g. Welch and Kubis, 1947a, 1947b; Taylor, 1951; Spence and Taylor, 1953; Spence and Farber, 1953). In the terminology of Eysenck (1952, 1953), in which introversion–extraversion and neuroticism are two orthogonal dimensions, anxiety neurotics are part of the groups known as Dysthymics, i.e. they have high scores on both the introversion end of the introversion–extraversion dimension and on the dimension of neuroticism. On the other hand hysterics and psychopaths have been shown to have high scores on the extraversion end of the introversion–extraversion dimension and on the dimension of neuroticism. Figure 1 will make this clear.

Personality Differences and the Socialization Process

“…The better deconditioners should have an 'advantage' comparable to that of the better conditioners. Because extinction occurs most rapidly where inhibition predominates (Pavlov, 1951-52), it would be the extraverts who possess this superior deconditionability (see also Franks & Laverty, 1955;Ader & Clink, 1957;Teplov, 1964;Gelder, 1968). However, if the differential factor applies as suggested, any advantage would again be cancelled.…”

Review of Perception and Communication.

“…Chemical effects are also of some interest. For instance, Franks and Laverty (1955) showed that sodium amytal would accelerate the rate of extinction of an eyelid conditioned response, and there was also some evidence that it slowed original conditioning although this effect was less well established. Scores on a questionnaire measure of extraversion were increased by the drug.…”

Clinical pharmacology of hypnotics and sedatives

“…Intravenous administration of amobarbital (180 to 360 mg.) in man reduces the number of conditioned responses (eyelid conditioning) during both acquisition and extinction. 67 In studies 164 on the conditioned galvanic skin response in normal individuals, the intramuscular administration of 200 mg. of amobarbital sodium 2 hours prior to testing had no effect on the unconditioned response (the shock) but did inhibit spontaneous recovery of the galvanic skin reflex. Unfortunately, there has been little effort to approach these aspects of the behavioral effects of hypnotics (as well as other depressants of the central nervous system) in an organized manner and to establish correlations between responses in man and other animals.…”