Patricia J. DeCoursey

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Environmental light cycles are the dominant synchronizers of circadian rhythms in the field, and artificial light cycles and pulses are the major tools used in the laboratory to analyse properties of circadian systems. It is therefore surprising that few studies have analysed the physical parameters of light stimuli that affect circadian rhythms. There have(More)
Behavioral aspects of photoentrainment of circadian locomotor activity rhythms were recorded for a nocturnal den-dwelling rodent, the flying squirrel,Glaucomys volans. Methods included both telemetric monitoring and infrared observations of animals under constant dark (DD) or light-dark (LD) schedules in either standard wheel cages or in newly developed(More)
The importance of circadian timing was evaluated for 18 months from late-April 1997 through October 1998 in a high-density population of free-living eastern chipmunks, Tamias striatus, at a 4-ha forest site in the Allegheny Mountains. Included in the radio-collared field group were 30 chipmunks with supra-chiasmatic nucleus-targeted lesions, 24 surgical(More)
Circadian activity parameters of 53 white-tailed antelope ground squirrels, Ammospermophilus leucurus, were measured to determine the role of the suprachiasmatic nuclei (SCN) pacemaker in their health and survival. Wheel-running activity was monitored in the laboratory with 44 individuals to document the presence of free-running circadian rhythms and(More)
Neural transplants into the third ventricle utilized to quantitatively assess the effectiveness of fetal tissue from selected brain sites in restoring circadian locomotor rhythmicity of adult hamsters rendered arrhythmic by lesions of the suprachiasmatic nuclei (SCN). Circadian function was continuously monitored in recording wheel cages under controlled(More)
The necessity of a circadian pacemaker, the suprachiasmatic nuclei (SCN), for survival was evaluated in a population of approximately 65 wild eastern chipmunks, Tamias striatus. The research involved over 3000 h of field-work between May 1995 and October 1997 on a study site at Mountain Lake Biological Station, Virginia. The 28 chipmunks randomly designated(More)
Experiments were carried out using simulated den cages to delineate specific characteristics of phase delaying in circadian photoentrainment of a nocturnal rodent, the flying squirrel. The principal experiments entailed presentation of one to five consecutive 15-min white-light pulses per activity cycle at activity onset to animals free-running in darkness,(More)