Bill E. Beckwith

Vasopressin analog (DDAVP) facilitates concept learning in human males

Abstract The effects of desmopressin acetate (DDAVP) were studied in normal males. Subjects were given 60μg of DDAVP, a placebo, or no treatment and were given several behavioral tests. DDAVP enhanced learning of all problems on a concept shift task but had no effect on visual memory, anxiety, blood pressure or heart rate. It was suggested that DDAVP may influence memory via its actions on attention.

Individual differences in the effect of time of day on long-term memory access

Individual differences in the pattern of circadian arousal on the speed of accessing information from long-term memory were investigated

Dose-dependent effects of hydrocortisone on memory in human males

Eighty male undergraduates were administered either glucose or 5, 10, 20, or 40 mg of hydrocortisone in a double-blind procedure. After 60 min they were asked to listen to eight 12 word lists and then asked to recall the words. In addition to the expected effects of rate of presentation, serial position, and practice there was a significant interaction between dose of hydrocortisone and practice. Early recall was facilitated by all doses used whereas later recall was facilitated by treatment with 40 mg and impaired by treatment with 5 mg. These findings are discussed in the context of the effects of pituitary adrenocortical hormones and memory function.

Vasopressin analog (DDAVP) improves memory in human males

One specific analog of arginine vasopressin, 1-desamine-8-D-arginine vasopressin (DDAVP), has been shown to improve learning and memory in humans. Healthy young male adult subjects treated with DDAVP demonstrated better memory for implicational sentences than did control subjects. The same treatment had no influence on women given the same memory task. These results suggest that DDAVP may have a sexually dimorphic effect on learning and memory.

Are learning and attention related to the sequence of amino acids in ACTH/MSH peptides?

Learning and attention were examined in rats after injections of one of several molecules related to adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (MSH). The initial phase of the learning process was linearly related to the length of the peptide with the smallest fragment (MSH/ACTH 4-10) improving learning the most and the largest molecule (ACTH 1-24) exerting no effect. Later stages of the learning problem, which were sensitive to the attentional state of the organism, resulted in U-shaped relations with the length of the same peptides. Enhancement of attention was significant only for the MSH compounds. These data indicate that some behaviors may be influenced as a function of the redundant information contained in the molecule while other behaviors may be discretely related to the specific conformation of the molecule.

Vasopressin analog influences the performance of males on a reaction time task

The effects of desmopressin acetate (DDAVP), a vasopressin analogue, were investigated using the Sternberg Item Recognition Task. This task requires a subject to memorize a target set of up to four digits and then quickly to decide whether or not a given probe was in the original memory set. Fifteen college aged males were used as subjects in this study. Subjects received, in a double blind procedure, 0.6 ml of DDAVP (60 micrograms) or an equal volume of vehicle solution during the first test session. One week later, during the second test session, the hormone-placebo treatments were reversed. The results indicated significant main effects for set size and decision type and an interaction between treatment and session. Treatment with DDAVP during the second but not the first session improved performance at each set size as compared to treatment with the vehicle. These results indicate that DDAVP, combined with experience on this task, improved attentional processes but did not influence memory, which would have been indicated by an interaction between treatment and size of memory set.

Central nervous system and peripheral effects of ACTH, MSH, and related neuropeptides

Adrenocorticotropic Hormone (ACTH), Melanocyte-Stimulating Hormone (MSH), and related peptides have been shown to have several neurogenic effects: alteration of cerebral protein synthesis, RNA synthesis, protein phosphorylation, and neurotransmitter turnover. Furthermore, there appears to be an ACTH containing circuit in the CNS which originates in the arcuate nucleus. Changes in concentration of the peptides in this family have been shown to alter electrophysiology, neuromuscular function, and behavior (e.g., grooming, learning) in infrahuman subjects. These findings suggest that the neuropeptides MSH and ACTH influence the capacity of an organism to efficiently evaluate information and influence the affective functioning of humans.

The effects of caffeine, impulsivity, and sex on memory for word lists

The present study examined the effects of caffeine on memory for supraspan word lists. Twelve groups of male and female college students classified as high or low impulsive received either 0, 2, or 4 mg/kg of caffeine. Female subjects were tested only during the menstrual phase of their cycle and were not taking oral contraceptives. Subjects listened to 12 word lists presented at one of four rates. Caffeine facilitated recall in females after practice with the task, but impaired recall in males only at the medium dose. The observed effects of caffeine were not influenced by subjects verbal ability, typical amount of caffeine consumption, or level of impulsivity. The results suggest that the effects of caffeine on females may vary according to the level of estrogen in the subjects system.

Failure of naloxone to reduce self-injurious behavior in two developmentally disabled females.

Three doses of Naloxone (0.1, 0.2 and 0.4 mg.) were compared to treatment with saline in a double-blind crossover design. Neither of the two female subjects altered their rate of self-injurious behavior as a result of treatment. The present results suggest that naloxone does not reduce self-injurious behavior in all individuals.

The actions of melanin-concentrating hormone (MCH) on passive avoidance in rats: A preliminary study

Melanin-concentrating hormone (MCH) is a hepadecapeptide hormone that is synthesized in the CNS and is responsible for melanosome aggregation in the teleost fish. Recent evidence suggests that this peptide hormone has a unique distribution in the mammalian brain, which leads to the speculation that it may serve as a neuromodulator. The present study was undertaken to explore the comparative effects of MCH to those of alpha-melanocyte-stimulating Hormone (MSH) (a neuropeptide that is known to influence learning) on the rate of extinction of a passive avoidance response in rats. Both MCH and MSH were administered SC at 10 micrograms per animal. Treatment with MCH appeared to hasten, whereas treatment with MSH appeared to delay, extinction of the passive avoidance response.