The behavioral effects of bilaterial lesions in the hippocampal formation are not clear-cut. Such lesions have not hindered the formation of "conditioned emotional responses" in the rat (Brady & Hunt, 1955) nor altered the acquisition rate of avoidance responses in the cat (Brady, Schreiner, Geller, & Kling, 1954). Recently, Kimura (1958) reported that lesions in posterior hippocampus produce adverse effects in the learning of a rather unusual avoidance response. Lesions of similar size in anterior hippocampus did not have any noticeable effect. However, Kimura's lesions were relatively small, involving less than half the structure.Allen (1940) reported the effects of nearly complete lesions of the hippocampus of the dog as it learned conditioned olfactory responses. Operated dogs were not inferior to normal animals in acquisition of the response, and in fact there was some suggestion they might even be somewhat superior to unoperated animals. To investigate the effect of near total removal of the hippocampus on the acquisition of an avoidance response, three groups of rats were prepared. In one group the hippocampus was removed under visual exposure, in another cortical lesions were made in the same area damaged during ablation of hippocampus in the first group, and the third group was made up of normal animals. METHOD SubjectsTwenty-eight male rats of the Long-Evans strain serves as 5s. Nine animals had bilateral ablation of the hippocampus, 9 had cortical lesions, and 10 served as 1 The research was supported in part by USPHS Grant M-3202. A preliminary report of this research was presented at the 1960 meetings of the American Psychological Association. unoperated controls. All 5s were between 3 months and 5 months old at time of surgery.

Rats with hippocampal damage, neocortical damage, and unoperated controls were given three tests of spontaneous activity. Hippocampal destruction was produced either by aspiration or electrolytic fulguration. Both hippocampally damaged groups spontaneously alternated at only "chance rates." Both were more active in exploration, but the aspiration group failed to display the normal decrements over time. The electrolytic hippocampals ran more in the exercise wheel, while the aspiration hippocampals ran less. IntroductionThe present experiment was undertaken to expand investigations of the role of the hippocampus in "spontaneous" (un rewarded) activity. Three different measures were used: spontaneous alternation in a T maze, exploration of a strange cage, and running in the exercise wheel. Reports on the effects of hippocampal lesions on activity in these situations already exist in the literature, but there is great variability between the studies in the location, type, and extent of leSions, as well as in general procedures. In the present study all animals were used in every task, and two methods of hippocampal destruction were employed. Apparatus Spontaneous alternation. An enclosed Tmazeoftheusual size and contruction was used, with illumination provided by a 7 1/2 w light placed over the choice point. Activity cages. Three wire mesh cages measuring 11 x 18 in and 11 in high were bisected on their longer axis by a photocell beam, interruptions of which were continuously recorded. The cages were used simultaneously in a darkened room. Exercise wheels. 'Three exercise wheels of 12 1/2-indiameter with 5 1/2-in wide tracks were used in a dark room. Each wheel turn was automatically recorded. McthodSubjects.

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6 rats with bilateral hippocampal lesions, 6 rats with neocortical destruction, and 5 normal rats were conditioned to bar press on CRF and then on DRL schedules of water reinforcement. In comparison with the neodecorticate and normal Ss, the hippocampectomized Ss showed lower rates of responding under CRF, higher rates under DRL, and, therefore, a lower percentage of reinforced responses under DRL.

Two groups of students in introductory psychology (691 in the fall semester and 569 in the spring semester) rated their teachers on a 46item questionnaire, derived largely from factor analyses of 145 items that had been used in previous studies elsewhere. The results were factor analyzed separately by sex and semester, and factor similarities obtained by Kaiser's method. 6 factors appeared which were consistent over the 2 administrations, in different semesters, with different students, and teachers.

Six rats with bilateral ablation of the hippocampus and six rats with extensive destruction of the neocortex were trained to enter a small compartment, while hungry, for a food reward. After 35 trials, spread over 4 days of training, the animals were given a shock while they were eating in the goal box. After the shock the rats with cortical lesions would not enter the goal compartment on the remainder of the trials given on the same day and only gradually began to re-enter over the next 2 days. The effect of the shock on the subjects with hippocampal ablation was slight and transient, suggesting that the ability to make passive avoidance responses was impaired.

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