STUDIES OF THE BRAIN STEM

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Abstract
Electrical stimulation of the antero-dorsal area of the thalamus is followed by chewing movements and slight muscular movements particularly of the neck with secondary circular movements of the bird. Electrical or mechanical stimulation of the inferior thalamic areas is followed by violent muscular movements of the neck, trunk, wings and legs, with forced circular or convulsive movements. Weak electrical stimulation or the application of ice to the thalamus is followed by shivering and irregular jerky movements of the entire body, associated with a rise in body temp. The body temp. is increased by the application of cold and by electrical and mechanical stimulation of the thalamus, indicating that elevation of the body temp. may be the result of any type of irritation. However, in addition to this traumatic factor it was found that the application of cold was a much more efficient means of stimulating an elevation of the body temp. than the same degree of slight traumatism without the cold stimulus. Direct stimulation of the thalamus causes erection of the feathers, a generalized sympathetic effect. The body temp. is increased because of the concomitant sympathetic stimulation of the erector muscles of the feathers, with increased conservation of heat, and the stimulation of the somatic striated muscles to shivering, tremor, and irregular jerking movements, with increased production of heat. When the body temp. has been increased to a certain level by the local application of ice to the thalamus, further stimulation by cold is followed by polypnea, a method of heat loss in the bird. The author was unable to cause a depression of the body temp. by local warming of the thalamus. Vomiting and defecation fre- quently followed thalamic irritation. Mechanical, electrical, and traumatic irritation of the inferior thalamic areas may be followed by severe diuresis, which persists in the fasting bird and leads to a real tissue dehydration which may be an essential cause of death in these birds.-F. T. Rogers.

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