[Features of the formation and reproduction of various conditioned responses during rat ontogeny].

Developmental characteristics are described of some conditioned excitatory and inhibitory defense reactions. Typical periods of learning speed and efficacy culmination are shown and compared with the periods of memory culmination. The learning and memory culmination period however do not coincide, they depend on the type of reaction, on the actual experimental conditions and on gender of the animals. The process of memory retrieval has also its typical developmental characteristics, and especially the time course of memory retrieval of partly learned active avoidance is of interest in rats of 4 - 6 weeks of age. Here the retrieval curve within 1 hour after learning has a "W" shape with two minima in the 10th and 40th minute which can be altered by some experimental procedures, such as REM-sleep deprivation, environmental stimulation, or pharmacologically. An inhibitory conditioned reaction was established in the newborn rat by means of a special method of passive avoidance which represents the earliest evidence of inhibitory conditioning in the ontogeny of mammals.