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U von Saint Paul

Publications and source records attributed to U von Saint Paul.

6 recordsLinked to original sources
PubMed1976

Brain temperature in the unanaesthetized chicken: its circadian rhythm of responsiveness to light.

Temperatures were recorded continuously for up to 4 days in the brain of 8 unanaesthetized, moderately restrained male chickens, kept in light-dark cycles (LD) of 30:30 or 60:60 min duration. In all cases, brain temperature was higher in L than in D. Temperatures increased or decreased immediately after the light was turned on or off, respectively, but did not reach a new level until after about 30 min. Average values of temperature obtained during the last 10 min in L and D were used for further analysis. The changes of brain temperature due to changes in light intensity were super imposed to marked circadian oscillations. The computed differences between L- and D-values were found to be a function of the circadian phase. For 4 out of the 8 chickens a uniform circadian rhythm of responsiveness to light could be demonstrated, with two maxima coinciding with the ascending and descending circadian slope, respectively. In view of the evidence suggesting brain temperature as a reliable measure of the degree of arousal, it is concluded that light has a stronger arousing effect on the chicken in the morning and in the evening than in the middle of the day or the night.

Animals↗
PubMed1973

Circadian rhythms of chicken brain temperatures.

1. Brain temperature was recorded continuously for up to 18 days in unanaesthetized adult male chickens. With the use of a guide box of plexiglas screwed into a trephine of the calvarium, several thermocouples could be inserted at various depths into the brain at the same time.2. While brain temperatures were being recorded, each chicken was placed in a small circular arena and kept either in a light-dark cycle (LD 12:12 hr) or in conditions of constant dim illumination (LL) within a soundproof chamber.3. Under LD-conditions, the range of oscillation (the difference between maximum and minimum within one period) in brain temperature at any one site was about 1.5 degrees C. During the 12 hr of light the temperature often reached a plateau for several hours. During darkness, a minimum of temperature was usually reached shortly after light-off. Brain temperature started to rise several hours before light-on.4. All eleven chickens tested under LL-conditions showed free running circadian rhythms of brain temperature, with mean periods varying between 22.75 and 25.00 hr (overall mean: 23.69 hr). The range of oscillation in LL-conditions was smaller than in LD-conditions, but was seldom less than 1.0 degrees C.5. In LD as well as in LL, continuous fluctuations of temperature with a much higher frequency were superimposed on the circadian cycle. The fluctuations occurred synchronously at all sites of the brain and were of the same order of magnitude (frequency and range) during wakefulness as during sleep.

Animals↗