T. Shetekauri, N. Tkemaladze, M. Aprosidze, T. Charekishvili, N. Tsertsvadze, T. Oniani, N. Oniani
Ilia State University, Tbilisi, Geprgia
Institute “Tengiz Oniani Laboratory of Sleep-Wakefulness Cycle Studies”
Avoidance is a response to danger without which animals cannot survive. The active avoidance (AA) experimental procedure is a tool through which avoidance behavior can be studied, in particular motivated instrumental behavior. This procedure is also used to study the formation of implicit memory in animals. The paradigm of incompletely learned active avoidance is often used.
The purpose of this study was to study the effect of changing the parameters of the conditioned stimulus (CS) in the task of incomplete learning of active avoidance and its retention after certain periods of time.
The testing subjects were white, wild laboratory rats. Experiments were carried out on two groups of animals. In the first group of animals, the standard procedure of active avoidance was used. In this procedure, the interval between the CS and unconditioned stimulus (US) was 5 sec and the intertrial interval was 1 min. When an animal performs an action of escape or avoidance, the presentation of both stimulus immediately stops. In the second group of animals, a similar procedure was applied with one exception: the action of the CS lasted for another 5 second despite the fact that the animals performed escape or avoidance.
According to our experiments for the first group of animals, the time-dependent retention curve of the learned task of active avoidance has a pronounced shape of the latin letter W. The first minimum value of this curve falls on the period of 1.5 hours after learning of the AA task, which corresponds to the minimum value of the Kamin effect retention curve. The second minimum occurs 4 hours after learning of the AA task.
According to the data of the second group, the prolongation of the presentation of the CS by 5 sec after the animal had performed escape or avoidance significantly reduced the degree of learning of the AA task. Under these conditions, the parameters of the retention curve also change. The minimum value of the curve is reached after an hour retention interval and does not change for two hours. After this period, there is a comparative improvement in the degree of the AA task reproduction.
The temporal characteristics of the retention curve of the degree of learning of the AA task are probably due to the nature of the process of the formation of the implicit memory in animals. This circumstance is also indicated by changes in the nature of the retention curve when a prolonged CS is used in the AA task. These conditions make it difficult to perform the AA task and, accordingly, the formation of memory in animals is obstructed.