Experimental studies on conditioned salivary reflexes in children.

Abstract

Summary.Experiments with conditioned reflexes were performed on a healthy boy, 9 years old, with the method of Krasnogorski. All conditioned reflexes were based on alimentary unconditioned reflexes, and the saliva from the right parotid gland was measured by a drop recorder. Each conditioned stimulus acted alone during 30 seconds, during which time the conditioned secretion was recorded. A system of conditioned reflexes was set up, consisting of 5 positive and 2 negative conditioned reactions. Positive conditioned reflexes were formed to red light (3 times) metronome signal (100 beats per minute, once) and the sharp sound of a buzzer (once). An other metronome‐signal (150 beats per minute) served as negative stimulus. In addition a conditioned inhibitory effect was formed on the light reaction by skin stimulation on the boy's right ankle. In experiments carried out under identical conditions 4–5 times a week this condition reflex system was used. In all 17 experiments were performed.The conditioned secretion caused by red light was an average of 13,2 ± 0,4 drops (50 observations), and the figure shows the striking regularity of the conditioned reflex action. The conditioned secretion to the positive metronome signal was 13,4±.0,4 drops (15 observations), and the much stronger sound of the buzzer caused an average of 15 ± 0,5 drops. The probable statistical difference is a proof for the validity of the law of force. The inhibitory reactions showed a similar marked regularity, the average of the secretion being 2 ± 0,2 drops (34 observations).Furthermore experiments were performed on the same boy in which conditioned reflexes were established on a taste stimulus. 2 cc 0,4 per cent NaCl, which gave no marked unconditioned secretion but positive sensation of salt, was used as conditioned stimulus. After being‐ reinforced 4 times a conditioned reflex to the taste stimulus was established. From the 35 observations in the ensuing experiments the average of the conditioned secretion was calculated to be 13,7 ± 0,3 drops. A negative conditioned reflex was formed on skin stimulation tog‐ether with salt, and later on 2 cc water was used as conditioned inhibitor on the positive salt reaction. The water preceeded the salt solution by 2 seconds, and the inhibitory effect was evident after six applications.