Frequency of Stimulation during Early Life and Subsequent Emotionality in the Rat

Abstract

Between 1 to 10 and 22 to 32 days of age rats were subjected to 3 min. of handling or electric shock at frequencies of 0, ½, 1, 2, or 4 times daily. Frequency of stimulation exerted significant effects either independently or in interaction with the age at which the manipulation occurred. For animals manipulated during the first 10 days of life, the relationship between magnitude of stimulation and emotional reactivity was curvilinear; stimulation at frequencies of up to 2 periods per day reduced emotionality, whereas emotionality in animals receiving 4 periods of stimulation per day tended to return to the level shown by control animals.