Biomedical subjects

B Givens

Publications and source records attributed to B Givens.

22 records · Page 2Linked to original sources

PubMed1994

Local modulation of basal forebrain: effects on working and reference memory.

The functional roles of the medial septal area (MSA) and nucleus basalis magnocellularis (NBM) in memory were investigated to determine (1) their relative contribution to working and reference memory, (2) their operation in spatial and nonspatial memory, (3) the temporal dynamics of the neural activity within these nuclei as they relate to mnemonic processes, (4) the neurochemical regulation of their activity, and (5) the importance of ACh for their function. Working memory was tested in a continuous conditional discrimination (CCD), and reference memory was tested in the CCD and a sensory discrimination (SD). Bipolar recording electrodes in the dentate hilus monitored hippocampal EEG (theta rhythm). Immediately prior to behavioral testing, trained rats were infused with tetracaine, scopolamine, or muscimol into the MSA or NBM, and the subsequent behavioral and physiological changes were measured and correlated. MSA infusions of all three drugs reduced the power of hippocampal theta and impaired choice accuracy in the CCD; the magnitude of both effects was greater for larger doses and steadily decreased over time after the infusion, producing a strong positive correlation between the power of theta and choice accuracy in the CCD. These infusions had no effect on measures of reference memory in the CCD or in the SD. The results demonstrate that rhythmic activity along the septohippocampal pathway reflects processing of nonspatial working, but not reference memory. NBM infusions did not affect hippocampal theta but did reduce choice accuracy in the SD and completely disrupted performance in the CCD. The NBM appears to have a critical role in both working and reference memory.

Animals↗

PubMed1993

Taking the jab out of needles.

Typically, health professionals regard injections and venipuncture as routine for them and a minor nuisance for the patient. Yet for others, needles arouse dread and anxiety. This fear of needles may even lead some people to avoid dental and health care.

Bloodletting↗

PubMed1991

Basal forebrain cholinergic system: a functional analysis.

This chapter has been organized empirically, focusing on the types of approaches that have been taken to understand BFCS function. This approach reflects the state of our knowledge about the behavioral and psychological functions of the BFCS. Considerable information has been gathered in the very short time that the BFCS has been the object of intense investigation. The results from the neurotoxic lesions and from the HACU studies provide some points of consistency and some puzzling differences. Both approaches to the study of basal forebrain function suggest that the MSA is involved in tasks that require spatial working memory; MSA lesions impaired choice accuracy, and HACU in the HIP was increased after performance. The pattern of results in simpler tasks is more difficult to interpret. In a left-right reference memory discrimination in a T-maze, MSA lesions did not impair acquisition or performance, whereas HACU in the HIP was activated during performance. This pattern of results suggests that although the MSA is engaged during this type of task, its activity is not necessary for normal performance. These, and other comparisons indicate the need for a systematic analysis of task demand (Olton, 1989b). Parametric manipulations of different task demands in a systematic fashion can indicate the extent to which the BFCS is involved in the function associated with each parametric manipulation. Ultimately, of course, the organization of this material should focus on particular psychological functions, rather than the techniques and procedures used to gather the information. Achieving this goal is going to require careful attention to the design of behavioral experiments so that definitive conclusions can be made about the extent to which the BFCS is involved in a given psychological function. A systematic application of task analysis can achieve this goal (Olton, 1986, 1989a, 1989b). For example, BFCS lesions in rats impair choice accuracy in spatial working memory tasks, and performance in these tasks engages the HACU system, at least in the HIP. If the spatial functions of this task involve the BFCS, then a nonspatial version of the task should produce a different pattern of results. If the spatial nature of the task is unimportant for BFCS function, then a nonspatial version of the task should produce the same results. By systematically changing one characteristic of the task at a time, the contribution of each component can be assessed.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗

PubMed1982

Endocrine-metabolic relationships in patients with leprechaunism.

Leprechaunism is a rare, heritable syndrome, associated with multiple dysmorphic and pathologic features, suggestive of an endocrine dysfunction. Few endocrine and metabolic studies have been obtained because of the rarity of the syndrome, and the small size and early demise of these infants. The authors present here the clinical, anatomic, and endocrine-metabolic studies of three patients, with a view toward careful delineation of the syndrome and further characterization of the metabolic defect.The most striking and consistent metabolic derangements present in all of these patients were fasting hypoglycemia (less than 20 mg/dL), postprandial hyperglycemia (more than 250 mg/dL), marked hyperinsulinemia (more than 2000 μU/mL), and severe insulin resistance (less than a 20 percent decrease in blood sugar with 0.3 to 1.0 U/kg of regular insulin IV). Hyperinsulinemia was observed in response to oral feedings and glucose infusion, and after tolbutamide. Insulin secretion was less marked with amino acid infusions. Normal increments in blood glucose occurred following alanine, galactose, and glycerol. Glucagon caused a rise in glucose 4 hours after a meal, but no response was seen after a 12-hour fast. Pituitary, gonadal, and adrenal hormone levels were normal, and there was a normal response pattern to GnRH and TRH. Hyperinsulinemia would appear to be the biochemical hallmark of this disease. Our previous studies were suggestive of a postreceptor defect in insulin action. The present endocrine-metabolic studies are compatible with this hypothesis. Interaction of supraphysiologic concentrations of plasma insulin with growth factor receptors, this may provide a partial explanation for some of the dysmorphic features seen in the disorder.

Adult↗