Biobehavioral Reviews最新文献

Evidence from the use of inhibitory drugs and antagonists to these drugs suggest a three phase model of memory formation, with phases sequentially dependent. Hyperpolarization due to potassium conductance changes following learning are postulated to underlie the formation of a short-term memory phase. Hyperpolarization associated with sodium pump activity appears to be involved in the formation of the succeeding labile phase. Long-term memory formation appears to involve sodium pump associated amino acid uptake occuring during labile phase formation. Protein synthesis is accepted as underlying the formation of long-term memory. Although reference is made to available evidence in the literature, this review deals in detail with evidence from our laboratories.

Research involving the effects of serotonergic and other pharmacological manipulations on tonic immobility is reviewed. An attempt is made to show how these findings parallel independent research involving precursor availability and drug-induced changes in the electrical activity of raphe neurons. Central serotonergic neuronal mechanisms appear to play a crucial role in modulating tonic immobility.

The exposure of pregnant guinea pigs to hyperthermia for 1 hr daily on 5 consecutive days produces learning deficits and reduced brain weight in the mature offspring, depending on the gestational age at which exposure took place. The offspring of those treated approximately one-third of the way through pregnancy (20–24 days) show significant deficits in learning performance, and reductions in whole and part brain weights. Those treated about two-thirds of the way through pregnancy (40–44 days) produce offspring which have lesser impairments in learning and a restricted reduction of brain weight. Hyperthermia in late pregnancy, (56–60 days) does not affect the learning or brain weights of the offspring. Several possible explanations for these findings have been examined; and the conclusions are that reduced brain weight is due to a blocking of mitosis at a period of rapid cell proliferation.

The purpose of this review is to evaluate several aspects of the retrograde transport of horseradish peroxidase as a neuroanatomical tracing technique. These include (1) methods for the delivery of tracer, (2) determination of the effective injection site, (3) perfusion techniques and histological processing, (4) identification of labelled cells, (5) the role of axonal injury in the uptake and accumulation of enzyme, (6) representative species and neural systems in which the method has been used, (7) comments on anterograde transport, (8) conjunctive or multiple tracing methods, and (9) a comparison of the retrograde transport method with other tracing techniques. The recent literature pertaining to these areas is reviewed, and where necessary, appropriate future experiments are proposed. It is concluded that the retrograde transport method offers a number of conspicuous advantages to tracing methods based on neuronal degeneration. Many unresolved issues merit further study, especially numbers (2) and (5). The retrograde transport method is compatible with and complements many histochemical and degeneration methods as well as autoradiography and electron microscopy.

ACTH appears to act directly on the brain to modulate some behaviors and to elicit others. This paper reviews the known responses of cerebral metabolism to ACTH in an attempt to elucidate the underlying mechanism of its behavioral activity. The cerebral localization of ACTH and its effects on the metabolism of cyclic AMP, RNA and protein and on the neurotransmitters dopamine, norepinephrine, serotonin and GABA are discussed. In some cases there are correlations between the neurochemical and behavioral responses. Potential mechanisms of ACTH action are discussed and directions for future research indicated.

Analysis of data which have been arranged in some form of a ratio is frequently employed by several disciplines which use pharmacological agents as independent variables. When the denominator term of the ratio is also a measured variable, it has been shown that correlations are induced between variables sharing the common denominator. Therefore, when data from drug conditions are calculated as ratios or percentages of data from non-drug controls, statistical analyses may produce misleading results due to the mathematical properties of ratios. Using data from a pharmacological experiment, comparisons were made between analysis of data in ratio form and analysis of data where the denominator variable is taken as a concomitant variable. The results indicate that analyses using ratios decrease the sensitivity of the statistical test. Alternatives to the use of ratios are discussed.

Research interpretations of the mechanisms by which various treatments produce retrograde amnesia are of three general types: (1) general modification of central nervous system excitability, (2) changes in the rate of brain protein or RNA synthesis, (3) alterations of brain neurotransmitter levels. Here, we review these interpretations and, within the framework of Kety's model, suggest that normal levels of biogenic amines during a critical period of memory storage may be essential for retention.