Relationship of the “Septal Syndrome” to Genetic Differences in Emotionality in the Rat

A problem of recent interest is that of the role of the septal region of the brain in emotional behavior. Working with rats, Brady and Nauta ( 1 ) and King ( 5 ) made lesions in the septal region and rated emotional behavior before and after surgery. Septa1 lesions, they found, increased strikingly the display of emotionality. The present experiment confirms these general findings. Its principal purpose, however, was to determine whether the heightened emotionality that follows septal lesions is a function of preoperative strain differences in emotionality. That such strain differences in affective behavior exist has long been recognized (see 3 ) , and a recent report by Broadhurst ( 2 ) carefully analyzes certain of these differences among five strains of rats. Casual observations before the experiment had suggested that rats of the hooded Lashley strain were normally more tense, excitable, fearful, and aggressive than albino rats of the Wistar strain, and this observation was borne out in the experimental tests. The two types of animals have provided two normal, but distinct, levels of emotionality, one high and the other low, upon which the effects of identical lesions have been studied. Comparisons were made by means of a six-component rating scale of emotional display.