Seven-minute rhythms in stable avoidance conditioning

Investigation of the “inextinguishable” locomotor avoidance reflex revealed periodic oscillating of reaction times, motor reaction times, and latent periods, when the conditional stimuli were applied every half minute. These rhythmic properties were verified by autocorrelation. Frequency distribution of all significant wavelengths occurring in rhythmic processes of stabilized conditioning showed seven-minute wavelengths for the most part and smaller numbers of wavelengths of 5 to 9 and 14 minutes. A significant number of wavelengths of 3.5 minutes was not seen. Locomotor avoidance conditioning permitted separate automatic registration of reaction times and motor reaction times. The two values showed synchronous periodic courses in stabilized conditioning, with the motor reaction times being longer. The periodicities found, thought to be due to controlling processes in the central nervous system, can be explained in either or both of two ways: the periodic courses represent a frequency range of a structured time mechanism in the sense of a “clock inherent in an organism”; the rhythms of conditional processes represent an adaptation mechanism in organism-environment interrelations. It can be assumed that the two mechnanisms work synergistically.     

A rat chamber and electrode procedure for avoidance conditioning

A method was developed for studying the reactions of rats to aversive shock. The distinctive features were the design of the chamber and a method of restraint that allowed the use of surface electrodes to deliver the shock. Advantages of this method were: (1) accurate specification of the shock actually received by the rat; (2) elimination of all unauthorized escape or avoidance reactions; (3) elimination of the shock scramblers and floor grids required with foot-shock; and, (4) rapid acquisition of performance under various avoidance procedures and various frequencies of shock delivery.     

Lever attacking and pressing as a function of conditioning and extinguishing a lever-press avoidance response in rats

Six experimental rats were conditioned to press one of two available levers to avoid shock. The levers registered bites as well as presses. For four of these rats, shock was contingent on lever bites when a specified time period had elapsed after the previous shock. An extinction period, in which only periodic noncontingent shocks were presented, followed avoidance training. Six yoked-control rats received the same sequence of shocks as did the corresponding experimental rats in both the conditioning and extinction phases. All six experimental rats repeatedly bit the avoidance lever. Four bit it more than the nonavoidance lever during conditioning, and five bit it more during extinction. Five of the six experimental rats consistently bit the levers many more times during each session than did their respective control rats, suggesting that avoidance conditioning facilitated lever biting. Rates of lever biting and pressing by all of the experimental rats and by some of the control rats were highest immediately following shock throughout both phases. During later portions of the intervals following shock, characteristic effects of conditioning and extinction were observed. This finding suggests that extinction of avoidance behavior by unavoidable shock presentations can be demonstrated more readily when shock-elicited responding is extricated from the data.     

A new apparatus for the study of avoidance conditioning in fishes

An apparatus for the study of avoidance conditioning in fishes is described. The chamber is cylindrical in shape, with shocking electrodes placed above and below the animals, and response is defined as swimming a predetermined distance in either direction along a circumferential path. This apparatus has several advantages over the conventional shuttlebox: (1)There is little constraint on the direction of swimming; (2) the magnitude of response (swimming distance) required for avoidance can easily be varied over a wide range; and (3) variation in the effectiveness of shock with the position of the animal relative to the position of the electrodes is minimized. Some sample data obtained in a free-operant experiment with goldfish are presented.     

A rapid and sensitive method for measuring the conditional emotional response II: On-the-baseline excitatory conditioning and extinction

The present study outlines a rapid and sensitive on-the-baseline conditional emotional response (CER) procedure. Using rats as the experimental subject, the method detects delay conditioning, incubation, extinction and spontaneous recovery. In addition, the method detects conditional responding using electric shock ranging from 0.23 to 0.50 mA as the unconditional stimulus. Because of its speed and sensitivity, the method shelters the subject from unnecessary long-term deprivation and pain.