Abstract
various parts of the forebrain were electrically stimulated to investigate a heat loss and heat production region within the brain in the hen. Unipolar electrodes were stereotaxically implanted into the forebrain under local anesthesia. Most region of the preoptic area and the hypothalamus responded to the stimulation with increase of respiratory frequency per minute (RF). Maximum respiratory frequency per minute (MRF) induced by the stimulation of the medial region of the preoptic anterior hypothalamus was significantly greater than that of the medial posterior hypothalamus or the lateral preoptic-hypothalamus. Especiallly the stimulation of the medial region anterior and posterior ventral to the anterior commissure induced polypnetic panting (the MRF was 155±23 compared to 26.3±1.3 of resting RF). The lateral region of the preoptic-hypothalamus was less effective in increasing RF. The stimulation of the region ventrocaudal to the anterior commissure in the medial and lateral hypothalamus induced shivering. Sitmulation of the lateral region the basal part of the thalamus and the lateral posterior hypothalamus inhibited respiration completely.
The results indicate that the heat loss center resides in the medial region ventral to the anterior commissure of the preoptic-anterior hypothalamus, and the heat production center in the ventrocaudal region of the anterior commissure at the medial and lateral hypothalamus in the chicken forebrain.
