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Biomedical subjects

B E Beckwith

Publications and source records attributed to B E Beckwith.

At least 37 records · Page 2Linked to original sources
PubMed1984

Asymmetry of facial expression in spontaneous emotion.

The observation that emotional expressions are more intense on the left side of the face is consistent with other evidence of the importance of the right hemisphere in emotional communication. However, the question has been raised whether it is truly spontaneous emotional expressions or only posed facial displays that show a left-sided asymmetry. We surreptitiously examined facial asymmetry during spontaneous emotional expressions as subjects remembered happy or sad experiences. These were contrasted with the subjects' posed expressions of happy or sad emotions. Both of these procedures resulted in more intense expressions on the left side of the face. The left-sided advantage was stronger during the spontaneous than the posed displays, and was observed for both happy and sad emotions.

Dominance, Cerebral↗
PubMed1983

Hydrocortisone reduces auditory sensitivity at high tonal frequencies in adult males.

The present study was designed to investigate the effects of treatment with cortisol on auditory tonal detection. College males were given either 20 mg of hydrocortisone or a placebo (dextrose) in a double blind design. Thereafter, thresholds were determined for frequencies of 500, 1,000 and 4,000 Hz using the method of limits. These results were then converted to change scores by using thresholds obtained for the same subjects at the same frequencies prior to treatment. Planned comparisons indicated that treatment with cortisol reduced sensitivity at 4,000 Hz but had no effects at other frequencies. Also, an overall analysis of variance indicated greater right ear improvement and greater improvement at lower frequencies. These findings are explained as resulting from the ability of glucocorticoids to alter cellular metabolism or reduce levels of adrenocorticotropic hormone.

Adolescent↗
PubMed1980

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.

Adrenocorticotropic Hormone↗
PubMed1976

Influence of three short-chain peptides (alpha-MSH, MSH/ACTH 4-10, MIF-I on) dimensional attention.

Male, albino rats were treated with alpha-MSH, MSH/ACTH 4-10, MIF-I or a diluent control solution and then tested on a visual discrimination problem. Immediately after acquistion of the visual task the animals were tested with a spatial extradimensional shift problem. The animals treated with the MSH/ACTH 4-10 and MIF-I acquired the discrimination nonsignificantly faster than animals treated with alpha-MSH or a placebo. A subproblem analysis of the EDS behavior indicated that the peptides significantly improved performance probably by affecting attention.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

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.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Effects of desmopressin acetate (DDAVP) on the learning of a brightness discrimination.

Sixty male albino rats received DDAVP, a placebo, or control treatment and were tested on a brightness discrimination task. Three groups (DDAVP, placebo, and control) were tested in the morning and three groups were tested in the evening. The acquisition and reversal of the brightness discrimination, along with the retention of the reversal problem after a 5-day retention interval were analyzed. Inspection of forward and backward learning curves plotted for each task revealed facilitated acquisition along with an initial impairment of reversal learning in those animals treated with DDAVP. These results support a memorial interpretation of DDAVP's effects. This was short-term in duration, as no retention effects were obtained. It was also found that DDAVP's effects were not influenced by diurnal processes.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

Influence of MSH and corticosterone on stimulus control over an operant response.

Several previous papers have indicated that MSH/ACTH-like neuropeptides facilitate the reversal of brightness discrimination in a runway task. The present experiment was undertaken to explore the development during both acquisition and reversal of stimulus control over an operant response. Male albino adult rats were treated daily with either 10 micrograms of MSH, 500 micrograms of corticosterone or a placebo in a double blind procedure during the establishment of an on-light control over availability of reinforcement. Having completed this regime the conditions were reversed so that reinforcement was present only when the chamber-light was off. The results indicated that treatment with MSH during acquisition produced a significant decrease in % correct responses compared to animals treated with either the placebo or corticosterone with neither of these latter groups differing from the other. During the reversal phase of training there was a trend for both MSH and corticosterone to lower % correct responses. The discussion focuses on other literature which has shown opposite effects of corticosterone on aversive and appetitively motivated tasks.

Animals↗
PubMedDate not supplied

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.

Adult↗
PubMedDate not supplied

Vasopressin and vasotocin facilitate reversal of a brightness discrimination.

Male albino rats received vasopressin, vasotocin, pressinoic acid or placebo and were tested on an aversively motivated brightness discrimination task. Treatment with both vasopressin and vasotocin had no effect on acquisition but facilitated the reversal of the discrimination. Pressinoic acid had an inconsistent effect. The results are interpreted to show that the C terminal of the peptides vasopressin and vasotocin influence potency of these peptides. Furthermore, the results are interpreted as showing that both vasotocin and vasopressin influence selective attention during aversively motivated tasks.

Animals↗
PubMedDate not supplied

Sentence memory affected by vasopressin analog (DDAVP) in cross-over experiment.

DDAVP has been shown to facilitate memory, especially retrieval, in humans. Healthy young male adult subjects received DDAVP (60 micrograms) in a cross-over design with a one-week interval between sessions. Results indicated that DDAVP improved immediate memory during the first but not the second testing session, particularly for low-verbal subjects. Treatment with DDAVP also facilitated delayed (one-week) recall in the opposite group, a cross-over interaction that suggests a retrieval locus for the DDAVP effect. Furthermore, since DDAVP improved immediate memory more for low-verbal subjects and delayed memory more for high-verbal subjects, it appears that individual difference factors will be important in understanding the effects of vasopressin on memory.

Adult↗
PubMedDate not supplied

Prenatal administration of arginine vasopressin impairs memory retrieval in adult rats.

Eight pregnant female rats were chronically treated via an osmotic pump with arginine vasopressin or placebo during days 13 to 19 gestation. All offspring were tested as adults in either a discrimination task or a 25 day retention of a passive avoidance response. The results revealed that rats whose mother had been treated with vasopressin did not differ from controls on the acquisition or reversal of a brightness discrimination; however, they did require more trials to reach criterion during the ten day memory test of discrimination reversal. Further, treatment resulted in impaired memory retrieval in male rats on the 25 day memory test, while female rats were not affected. Treatment did not influence body weight. The results indicated that vasopressin administered during the prenatal period of development may have had a teratogenic effect on memory retrieval.

Animals↗
PubMedDate not supplied

The effects of structure-conformation modifications of melanotropin analogs on learning and memory: D-amino acid substituted linear and cyclic analogs.

Alpha-MSH has a wide variety of putative biological activities in addition to its classical melanocyte dispersing activity. Since each of these activities appears to be mediated by a discrete receptor, this peptide is an excellent candidate for exploring conformational restrictions which determine the chemical-physical basis for hormone action on specific activities. Experiments One and Two evaluated several cyclic and linear analogs of alpha-MSH on retrieval of memory during the reactivation of memory for a passive avoidance response following hypothermia-induced amnesia. Three of the cyclic analogs appear to have enhanced the peptide's ability to serve as a reactivation agent. One of the linear Nle4,D-Phe7 analogs antagonized whereas three others enhanced reactivation. The D-Phe7 substitution in cyclic analogs did not affect reactivation. Another group of animals were trained on a step-through passive avoidance task and tested 25 days later. The cyclic analog enhanced memory whereas the D-Phe7 analog and alpha-MSH had no effect. Finally, two analogs were tested on a black-white discrimination. Although the cyclic analog had no effect on either acquisition or reversal of this learning, the Nle4,D-Phe7 analog significantly impaired reversal learning. The results from these preliminary studies suggest that structural modifications of alpha-MSH do alter its potency and pattern of actions in learning and memory situations.

Amino Acid Sequence↗