Behavioral Effects of Mammillothalamic Tractotomy in Cats

Role of freezing and fear in avoidance decrements following mammillothalamic tractotomy in cat: I. Two-way avoidance behavior

“…Six mongrel cats, four males and two females, were trained in the two-way CAR procedure described by Thomas et al (1963), Psychon. Sci., 1966, Vol.…”

“…When a cat had reached the learning criterion, electrolytic lesions were stereotaxically aimed bilaterally at MTT. Lesioning and histological procedures have been described by Thomas et al (1963). Postoperatively animals were tested for three days (60 trials) under preoperative conditions, except that no shock was administered.…”

“…Four naive, mongrel cats were trained in a two-way CAR. Procedures and apparatus are described by Thomas et al (1963).…”

“…Although it has been shown that in cats retention of a two-way (shuttle) conditioned avoidance response (CAR) is severely reduced following lesions of the mammillothalamic tracts (Thomas, Fry, Fry, Slotnick, & Krieckhaus, 1963;Krieckhaus, 1964),theexactroleof the mammillothalamic tract (MTT) in avoidance behavior is not clear. Thomas et al (1963) suggested that the avoidance decrements might be a result ofMTTlesions increasing the likelihood that the innate response of freezing would become prepotent when fear producing stimuli were presented, while Krieckhaus (1964) proposed that the observed changes in freezing are more likely only secondary to an immediate effect on avoidance behavior. The present study will evaluate the role of freezing and other manifestations of fear in avoidance decrements following MTT lesions.…”

Acquisition of the two-way avoidance response in chicken compared to rat and cat

“…This difference is particularly striking as one ascends the phylogenetic scale within mammalia. It is well established that sectioning of the pathway from the mammillary bodies to the anterior thalamic nuclei (mammillothalamic tractotomy) produces a profound deficit in the retention of the difficult conditioned avoidance response in two species of mammalia-cat (Thomas, Fry, Fry, Slotnick, & Krieckhaus, 1963;Krieckhaus, 1964;Krieckhaus & Chi, 1966) and rat (Krieckhaus, 1965). The above observations raise the question of whether infra-mammals might not be deficient in the acquisition of such avoidance responses since they appear to be deficient in a neural system which seems to mediate this behavior in higher organisms.…”