SUMMARY
Bilateral lesions produced by electrocoagulation in the basolateral and medial amygdaloid nuclei, subtotal amygdalectomy as well as implants of actinomycin D and cholesterol were all found to have profound effects on brain ribonucleic acid (RNA) base percentages and ratios. The most consistent effect was that on the pituitary and was produced by all treatments. Generally, the hypothalamus and frontal cortex showed varying effects due to the treatments, but the cerebellum uniformly showed no responses to the various treatments. Lesions placed in the medial amygdaloid complex and subtotal amygdalectomy had the greatest effect in changing the RNA base ratio. The bases adenosine monophosphate (AMP), cytidine monophosphate (CMP), guanosine monophosphate (GMP), and uridine monophosphate (UMP) were found to be the most affected. The newly synthesized RNA was found to be rich in UMP and deficient in AMP and CMP when compared to normal animal brain tissue. The assumption is made that lesions in the amygdala bring about an activation or stimulation of a genomic nature to produce specific RNA for a particular neural function.