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Biomedical subjects

E W Powell

Publications and source records attributed to E W Powell.

10 recordsLinked to original sources
PubMed1978

The cingulate bridge between allocortex, isocortex and thalamus.

The Fink-Heimer silver impregnation and the autoradiographic methods were used to study the fiber projections of the cingulate cortex in the squirrel monkey. It was found that this cortex provides inputs to the straitum, thalamus and several areas of isocortex. Evidence was found for a number of fiber projections (1) Fibers from the anterior limbic area were traced to the central part of the head of the caudate nucleus, putamen, septum, dorsomedial nucleus of the thalamus, anterior hypothalamus and lateral basal nucleus of the amygdala. (2) Projections from the cingulate area were traced to the lateral part of the head of the caudate nucleus, putamen, and to the centromedian, anterior, lateral dorsal, and lateral ventral thalamic nuclei and to medial nuclei of the base of the pons. (3) There were porjections from the retrosplenial area of the anterior, lateral dorsal, dorsomedial, and posterior thalamic nuclei and lateral nuclei of the pons. These results indicate that most of the cingulate gyrus is an intermediate structure between the thalamus and overlying cortex. The anterior limbic area forms a bridge between the thalamus and other areas of the cingulate gyrus and the frontal cortex. (4) the retrosplenial area and the posterior part of the cingulate area bridge the adjacent visual snesory association cortex and pelvic areas of the snesory motor cortex, respectively. These areas of the cingulate gyrus project directly to the striatum as well as to the thalamus, structurally providing limbic system input to subcortical motor structures.

Animals↗
PubMed1978

Effects of amygdaloid lesions on reproductive function of grouped caged mice.

Amygdalotomized, sham-operated and intact wild-derived house mice of both sexes were group-caged (8-10) or singly caged for 3 weeks. The weights of ovaries (p is less than 0.05) and uteri (p is less than 0.01) were less in intact and sham-operated grouped females compared to singly caged intact and amygdalotomized females. The weight of the reproductive organs in amygdalotomized grouped female mice was not different from singly caged controls. Body weights among amygdalotomized grouped females were heavier (p is less than 0.05) than singly caged controls. Seminal vesicle weights of intact and sham-operated grouped males were less (p is less than 0.05) than that of singly caged controls and grouped amygdalotomized males. Plasma LH values from the various groups coincided with the morphological data. These results support the hypothesis that increased population density impairs reproductive function in mammals. Perhaps the effects of decreased pituitary-gonadal function associated with overcrowding are mediated via amygdalar nuclei.

Adrenal Glands↗
PubMed1977

Baseline sleep-wake patterns in the pointer dog.

The 24-hr electrographic patterns (EEG, EOG, EMG) of six normal pointer dogs were recorded in a laboratory setting. Two states of sleep (slow-wave and rapid eye movement) and wakefulness (alert and drowsy) were identified. The total recording period comprised 44% of alert wakefulness, 21% of the drowsy state, while slow-wave sleep occupied 23% and REM sleep 12% of the time. The mean length of a REM sleep episode averaged 6 min and the mean REM sleep cycle was 20 min. The mean polycyclic sleep-wake cycle was 83 min. Sleep episodes averaged 45 min and the mean waking episode was 38 min. There was an average of two REM sleep episodes per sleep-wake cycle. The dog has a propensity to sleep over a 16-hr interval from 1300 to 0500 but the most sleep occurred between 2100 and 0400 hr during darkness.

Animals↗
PubMed1976

Connections of the nucleus accumbens.

Reports from previous works has given different classifications for the nucleus accumbens. There also appears to be a general lack of information regarding the fiber connections of the nucleus. The present investigation was undertaken to clarify the connections of this structure. Silver impregnation methods were used to discern some of the afferent fibers of the nucleus, and autoradiographic techniques were used to locate target areas of efferent projections. Afferents were found to be predominately from the septum. Other sources of possible afferents were the mid cingulate gyrus and the ventral nucleus of the diagonal band. No argyrophilia was observed in the nucleus accumbens following transection of the fornix body, lesions of the anterior orbital frontal cortex or anterior cingulate gyrus. On the basis of grain counts made from autoradiographic studies, the nucleus accumbens projects predominately to the lateral hypothalamus. Counts above background were found in the cingulate gyrus, septum, ventral nucleus of the diagonal band, midline thalamic nuclei, habenula, caudate and substantia nigra. Thus, efferent projections appear to distribute to both limbic and extrapyramidal structures. Considering these connections and the functions reported by various workers the nucleus accumbens may serve as bridge between limbic and extrapyramidal motor systems effecting limbic influence in some movements.

Animals↗
PubMedDate not supplied

Nomifensine chronopharmacology, schedule-shifts and circadian temperature rhythms in di-suprachiasmatically lesioned rats--modeling emotional chronopathology and chronotherapy.

Some emotional disorders are associated with alterations of biological rhythm characteristics ('echronism'). Chronotherapy aims empirically to 1. optimize the kind and timing of conventional psychopharmacologic treatment and, need be, to use such old or new molecules in the rational endeavor to 2. correct (disease-determining) rhythm alteration directly. With respect to the first aim, a reduction by timing of undesired pharmacodynamic effects, as well as an amplification of empirically desired ones, can be dramatically illustrated by circadian rhythms in tolerance to many drugs affecting the central nervous system of rodents. A more rational approach is aimed at correcting ecchronism. The new antidepressant drug, nomifensine, achieves this task in rats with bilateral suprachiasmatic lesions, exhibiting in the telemetered core temperature an echronism of varying degrees. In this model system for the chronobiotic treatment of ecchronism, the properly timed administration of nomifensine speeds the adjustment of bilaterally (suprachiasmatically) lesioned rats to a shift in the synchronizing light-dark schedule. With methodologic provisions, notably for treatment timed by pertinent marker rhythms, nomifensine deserves clinical tests in psychochronotherapy.

Animals↗