EN
The aim of the study was to examine the neurochemical background of differences in the individual responses to conditioned aversive stimuli, using the strength of a rat conditioned freezing response (the contextual fear test), as a discriminating variable. It was shown that high responder (HR), i.e. rats with duration of a freezing response one standard error, or more, above the mean value, had a higher c-Fos activity in the FrA and PrL prefrontal cortical areas, and stronger 5HT immunostaining in the FrA. However, these animals had lower CRF immunostaining in the same cortical areas in comparison with low responder (LR), i.e. rats with the duration of a freezing response one standard error, or more, below the mean value. The LR group vocalized more during test session in the aversive band, and had higher serum levels of corticosterone, examined 10 min after test session. It was shown that different natural patterns of responding to conditioned aversive stimuli are associated with different expression of CRF and serotonergic- innervation of prefrontal cortical areas.