| Abstract: | Symptoms produced by repeated daily injection of insulin (3 units/kg i.v.) in dogs revealed the principle of fractional conditioning: the general behavior and changes in the cortical EEG characteristic of insulin action could become a conditional reflex (evoked by the injection of physiological saline i.v. and a CS)—while the blood sugar level, the heart rate, the EKG, and body temperature did not become CRs. This split illustrates the principle shown by Gantt that centrally-mediated effects of an agent are conditionable while those resulting only from direct peripheral action cannot become CRs. From this principle it may be assumed that the effects of insulin (behavioral, EEG) are mediated through the central nervous system, while other insulin effects (those not conditionable) are a result of peripheral action. Two methods of blood sugar determination (Hagedorn-Jensen and glucose oxidase) in both venous and arterial blood were used in these experiments, and the data resulting from 14,056 determinations were analyzed. |
