Kazimierz Zielinski

CS modality transfer of two-way avoidance in rats with central and basolateral amygdala lesions

Post-lesion acquisition of two-way avoidance and subsequent transfer to two warning signals (conditioned stimulus, CS) of different modality were investigated in 60 rats. In Experiment I the animals were originally trained with less salient (darkness) CS, then transferred to more salient compound (darkness and white noise), and finally to white noise CS. The opposite arrangement of the conditioned stimuli (CSi) during the subsequent stages was employed in Experiment II. In control animals, avoidance acquisition was faster and the intertrial responding (ITR) rate lower with the auditory than with the visual CS. Lesioned rats learned avoidance responses more slowly, independently of CS modality. The transfer to other CSi revealed dramatic between-group difference in the level and consistency of avoidance response, shuttle-box latencies and ITR rate. In control animals, transfer to more salient CSi enhanced avoidance performance, whereas change to less salient CS decreased it. Rather small changes in shuttle-box performance and consistency of avoidance response due to CS modality were seen in rats with the basolateral lesions. In contrast, central nucleus injury caused a strong deterioration in the avoidance transfer, especially when the visual CS followed the acoustic one. The results indicate differential involvement of the basolateral and central amygdala nuclei in stimulus-processing mechanisms of instrumental defensive behavior.

The role of conditioned stimulus termination in short-latency avoidance responding in cats

The behavioral effects of two procedures for bar-pressing avoidance training in cats were studied. In one procedure conditioned stimulus (CS) termination was response-contingent on both shock and non-shock trials; in the other the minimal duration of the CS was equal to the CS-US (unconditioned stimulus) interval. When avoidance responses did not terminate the CS short-latency avoidance responses were not acquired, the cats made more intertrial responses, and removal of the proreal and orbital gyri interfered more with avoidance responding than was observed in the other group. Abolition of shock application and introduction of a fixed duration of the CS resulted in extinction of the avoidance responses, which was more rapid in cats trained under the response contingent CS termination procedure. The data suggest that responses performed during the CS-US interval should be divided into two subclasses: short-latency responses which not only avoid pain but also avoid fear conditioned to the CS, and long-latency responses which avoid pain and escape from the fear state.

Effects of partial lesion of dorsal hippocampal afferent and GM1 ganglioside treatment on conditioned emotional response and hippocampal afferent markers in rats

Acquisition of the conditioned emotional response (CER) in 32 male hooded rats previously learned to press a bar for food and divided into four groups was studied. Two groups received electrolytic lesions of the dorsal hippocampal afferent and were thereafter injected either with GM1 ganglioside (30 mg/kg daily) or with buffer. Two remaining groups were sham operated and similarly injected. The partial hippocampal deafferentation evoked immediate enhancement of bar presses rate which persisted during the 2-week period of testing. CER training undertaken 2 days after surgical procedures appeared unsuccessful, whereas similar training with a cue of different modality initiated a week later resulted in acquisition of conditioned suppression of bar presses in all groups. Toward the end of training the conditioned suppression was more pronounced in lesioned than in control rats. The GM1 injections attenuated the conditioned suppression in control rats, presumably due to an antinociceptive role of ganglioside treatment. Behavioural training did not change the normal distribution pattern in cholinergic and serotonergic hippocampal afferent markers showing dorso-ventral gradient along longitudinal axis. The lesion-induced decrease pattern was also not affected. However, in contrast to previous findings in non-trained animals, the GM1 treatment was not effective in protecting against degenerative changes in the hippocampus of trained rats.

ESCAPE AND AVOIDANCE CONDITIONING

Publisher Summary This chapter focuses on escape and avoidance conditioning. Nearly all the theories of avoidance conditioning assumed the crucial role of fear both for acquisition and for maintenance of avoidance responding. The avoidance responses have to be split into two categories with different mechanisms for short and long-latency responses. However, the distinction between these categories cannot be grounded on strictly temporal basis. If short-latency responses are avoidances of fear, all parameters increasing the strength of the conditioned fear response will shorten the timespan between the CS onset and the escape from fear, that is, long-latency avoidance responses. In a study described in the chapter, all the methods of avoidance extinction allowed obtaining information that contingencies between conditioned stimuli and instrumental response were not the same as before. Only then, a change in instrumental responding could occur.

Science in Poland

The Nencki Institute in Warsaw was founded in 1918 to honor one of Poland’s most distinguished biochemists, Marceli Nencki. Since its inception, the institute has evolved from a confederation of privately supported laboratories to a center of research productivity intimately associated with the Polish Academy of Sciences. Early relations with Pavlov’s laboratory laid the foundation for the emergence of a Polish School of Neurophysiology under the leadership of Jersy Konorski. The impact of Konorski and his colleagues has transformed the interpretation of conditioning to include a systematic physiologic basis that more adequately considers the psychology of learning processes. The prestige of the Nencki Institute within contemporary Eastern European and Soviet science was achieved despite the economic pressures on a new nation and its total devastation of World War II. Moreover, the more than 60 years of scientific work in an independent Poland have provided a critical transition between Eastern and Western research efforts, and the Nencki Institute has filled a leading role in facilitating communication among scientists.