Two-dimensional determination of thermosensitive sites within the goat's hypothalamus

In two conscious goats with chronically implanted multithermodes the distribution of thermosensitive sites within the anterior hypothalamus was determined. Changes in heat production at Ta=+5 degrees C and changes in respiratory evaporative heat loss at Ta=+33 degrees C in response to discrete temperature stimuli were measured and the magnitude of the responses was correlated with the histologically assessed position of the probes transmitting the stimuli. In both animals the array of probes was centered close to the center of the thermosensitive area. The density of thermosensitive structures increased toward the center of the area covered by the probes. The most sensitive points were situated close to either side of the midline in those frontal planes which contained the nuclei supraoptici and paraventriculares. No difference was found between cold- and warm-sensitive sites.