This experiment was designed to confirm the occurrence of imprinting and to test HESS's “Law of Effort”. Forty White Leghorn chicks were used for subjects. These were assigned to 4 groups according to the first exposure procedures at 14-20 hr. posthatching. Two groups of them were the Experimental Groups which were given first exposure to the red cube stimulus object in the 200×60×30 cm straight runway (Fig. 1) and the other 2 groups were the Control Groups which were treated the same as the Exp. Groups except without the stimulus object in the runway. Two groups (one from the Exp. Groups and the other from Cont. Groups) were the Movement Confinement Groups which were received first exposure under movement confinement, and the other 2 groups (from the remainders of the Exp. and Cont. groups) were the Movement Free Groups which were not received the confinement procedure. About 48 hr. after first exposure, the following responses were measured for 20 min. in the same apparatus.
It was found that :
1) There were no significant differences between the Exp. and Cont. Groups in total following time (Fig. 3), mean following time per response (Fig. 4) and number of following responses (Fig. 5).
2) The Movement Free Groups were significantly longer than the Movement Confinement Groups in mean following time per response (Fig. 4) and there was a significant tendency in number of following responses between these groups.
3) Following latency in the Movement Free Exp. Group was shorter than other 3 groups (Fig. 2).
From these results, it was concluded that :
1) Because there was no difference in the effect of first exposure between the Exp. and Cont. Groups, imprinting did not seem to occur in the Exp. Groups. This might suggest that there was a species difference in imprinting.
2) The “Law of Effort” would be supported, for the permission of following of stimulus object in first exposure lengthened mean following time per response in later test.

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The present experiments were designed to test the effect of actinomycin D on the avoidance learning in the goldfish and to discuss the nucleic acid theory of learning and memory. Subjects were given four measuring sessions (Exp. I) and four training sessions (Exp. II & III) every other day. In all cases actinomycin D was injected intracranially.
In Exp. I, the effect of actinomycin D (2μg, 1μg, 0.5μg) on the activity was tested. The drug was injected before 30 min. of every measuring session. The number of sections traversed in the tank was used as the amount of activity. It was found that actinomycin D has no effect on the activity.
In Exp. II, the effect of actinomycin D (2μg) on the avoidance learning was tested. The effect was injected immediately after every training session. The apparatus was shuttle-box, the conditioned stimulus a light for 20 sec. and the unconditioned stimulus the electric shock of alternating current. It was found that there was a significant difference in the interaction between groups and trials. Therefore, it might suggest that actinomycin D has the inhibitory effect on the speed of the acquisition of the avoidance learning.
In Exp. III, the effect of actinomycin D injected before 30 min. of trainings and its doses (2μg, 1μg, 0. 5μg) on the avoidance learning was tested. The experimental procedure was the same as Exp. II. It was found that there may be some difference between groups and is a significant difference in the interaction between groups and trials. The results might suggest that the avoidance learning was blocked by actinomycin D injected before training and the ratio of its acquisition was depressed in accordance with its doses.
Consequently, the present experiments might suggest that d-RNA is necessary to the acquisition of the avoidance learning and might support the nucleic acid theory of learning and memory.

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The purpose of this study is to examine previous theories of hippocampal electrical activity in relation to behavior with special emphasis on VANDERWOLF's hypothesis, based on new data with rats as subjects, in which hippocampal activity was studied during spontaneous behavior patterns and active avoidance conditioning with MILLER-MOWRER box.
The main results were :
(1) Hippocampal EEG during spontaneous behavior.
Theta rhythms of 79 Hz were clearly observed during such behaviors as searching and rearing without locomotion and walking forward or around, as well as during head and body movements without locomotion. When animals were awake but motionless, hippocampal EEG consisted of desynchronized activity was also observed.
(2) Hippocampal EEG during active avoidance learning.
Hippocampal theta activity was not produced by the presentation of CS (2000 Hz pure tone) in habituation trials. In avoidance training, CS elicited a clear train of theta activity (79 Hz) starting a few seconds before the occurrence of avoidance responses. In the final state of avoidance learning, theta activity occurred immediately after the onset of CS and theta frequency increased to 911 Hz just before shuttling to the next compartment.
From these and other results, hippocampal theta activity was shown to be associated not only with voluntary movement as suggested by VANDERWOLF but also with arousal level or general attention level.

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