Blood glucose and brain function: interactions with CNS cholinergic systems

We recently found that glucose injections attenuate amnesia and hyperactivity produced by scopolamine, a muscarinic antagonist. The present study examined whether glucose would augment behavioral effects produced by a muscarinic agonist, physostigmine. In experiment I, doses were first determined for which neither glucose (10 mg/kg) nor physostigmine (0.05 mg/kg) altered scopolamine-induced hyperactivity. However, combined glucose-physostigmine injections significantly reduced scopolamine hyperactivity. Experiment II evaluated the effects of glucose on physostigmine-induced tremors. Glucose (10, 100, and 250 mg/kg) or saline injections were given 20 min before physostigmine injections (0.4 or 0.05 mg/kg). Observations of glucose effects on the severity of physostigmine-induced tremors were then obtained at 5-min intervals for 25 min after physostigmine injections. Glucose (100 mg/kg) significantly facilitated the onset of tremors when injected before either dose of physostigmine, and augmented (at 100 and 250 mg/kg) tremor severity when injected before the lower dose of physostigmine. These findings indicate that glucose can facilitate the actions of a cholinergic agonist on two behaviors, locomotor activity and tremors, adding support to the view that circulating glucose levels can modulate central cholinergic function. More generally, the results provide additional evidence that circulating glucose levels can influence brain function.     

Novel effect of chronic corticosterone treatment on escape behavior in rats

Chronic administration of corticosterone in rats (4-35 mg/kg/day) produces a marked dose-dependent increase in the frequency of escape behavior observed when animals are held by the tail on a flat surface. The effect is fully developed after 3 days treatment. It is not the result of an increase in spontaneous motor activity since the hormone tends to reduce the latter behavior. Adrenalectomy decreases the escape behavior and tends to do so to a greater degree in rats subjected to chronic stress (restraint) than in nonstressed controls. The results suggest that endogenous corticosterone serves to maintain the above escape behavior during chronic stress.     

The relationship between role concerns,preferences for slimness,and symptoms of eating problems among college women

Eating problems and body dissatisfaction among women have been associated in the literature with both slim standards of female bodily attractiveness and concerns about success and failure. This study demonstrates that among college women the desire for slim, noncurvaceous bodies associated with dieting and binging is correlated with an emphasis on physical attractiveness, and thus may be related to the desire to match the currently fashionable slim standard of female bodily attractiveness. A similar desire for slim, noncurvaceous bodies associated with purging and underweight is correlated with an emphasis on intelligence or professional success, and thus may be related to a desire to avoid the curvaceous figures that have been found associated in the minds of males and females with a perceived lack of intelligence.     

Evidence for a possible functional interaction between serotonergic and cholinergic mechanisms in memory retrieval

A total of three experiments were conducted. In Experiment 1, the dose-dependent effects of the pretest administration of the serotonergic agonist alaproclate and the selective muscarinic cholinergic agonist oxotremorine, alone and in combination, were assessed in a one-trial inhibitory avoidance task. A clear dose-dependent enhancement of performance was demonstrated as a result of all three treatment conditions, which could not be explained in terms of nonspecific effects of the drugs on behavior in general. In addition, the facilitation of retrieval performance produced by the combined treatment of alaproclate and oxotremorine was observed at dose levels well below those observed following administration of either compound alone. In Experiment 2 attempts were made to block the enhancements of retention resulting from the different treatment conditions (alaproclate, oxotremorine, or the combination of alaproclate and oxotremorine) by pretreating the mice with either scopolamine (a muscarinic cholinergic antagonist) or quipazine (a serotonergic agonist). The results of these experiments indicate that (a) quipazine completely blocked the enhancement of retrieval resulting from alaproclate but not that following oxotremorine or oxotremorine in combination with alaproclate, while (b) scopolamine blocked the enhancement of retrieval resulting from oxotremorine alone as well as that resulting from alaproclate plus oxotremorine but failed to block the memory enhancement resulting from alaproclate. The present results lend further support to the view that both serotonin and acetylcholine play important roles in memory retrieval. More importantly, the results of the present series of experiments provide additional support for a functional interaction between the serotonergic and cholinergic nervous systems in the mediation of behavior.     

A parallel but not necessarily connectionist model of the auditory system

The basic processing elements (the neurons) in the brain operate in the millisecond range and are about a million times slower than a computer (Feldman, 1985). In order to make up for this lack of computational speed, the brain must use a parallel multisynaptic method to transmit information. This paper presents a parallel processing model of the auditory system; the model accounts for the frequency and the sound-localization information.     

The role of perceptions and attributions for response-outcome noncontingency in learned helplessness: A commentary and discussion

Three papers in the Journal of Personality (Oakes & Curtis, 1982; Tennen, Drum, Gillen, & Stanton, 1982; Tennen, Gillen, & Drum, 1982) report that behavioral deficits characteristic of learned helplessness occur independently of perceptions of and attributions for noncontingency. The present article discusses the problems for the cognitive mediational component of helplessness theory raised by these three papers. It is argued that while these papers do not seriously challenge helplessness theory because they fail to test adequately the central proposition of the model, they point to the theory's need for greater elaboration of the processes or mechanisms linking objective experiences, perceptions, attributions, expectations, and behavioral effects of uncontrollability. Suggestions for some of the additional mediational processes a revised helplessness theory should incorporate are offered, followed by a discussion of the role of these processes in leading to the relatively greater support found for perceptions and attributions as mediators of behavioral helplessness in natural vs. laboratory environments.     

What is the “front” of a simple geometric form?

A total of 670 undergraduate Ss were tested in three studies conducted in an attempt to define a set of cues that minimally specify perceived “frontness” and “backness” of objects. In Experiment I, Ss were instructed to identify the “front” and “back” of printed squares to which no, one, or two circles were attached. In Experiment II, different Ss made the same kind of judgment to a wider range of geometric forms. In Experiment III, different Ss judged the direction of “imagined” movement of forms from Experiment I. The results indicated that the “front” and “back” are asymmetric opposite sides, with “front” the side most different from the rest and the side toward which the form is imagined to be moving.