The Role of Benziodiazepines in the Differential Conditioning of Contextual and Acute Auditory Stimuli: A regional comparison of single-unit activity in the lateral septum and other limbic sites

The effects of the benziodiazepine chlordiazepoxide (CDP) were examined in a\ud contextual and classical fear conditioning paradigm. Effects were measured in seven animals assessing overall movement behavior as well as single-unit activity in various limbic sites. After electrode implantation, rats were subjected to two days of spontaneous unit activity and movement recording in two drug conditions (saline and CDP trials) over five days of tone/shock pairings. On conditioning days, both movement and unit activity\ud were recorded twenty seconds before the tone (preCS) and during the twenty second CS\ud presentation, thereby providing a comparison between reactions to the context and the cue\ud itself. There was a significant increase in movement activity over conditioning days in both\ud the preCS and CS conditions, an indication that the animals successfully associated both the context and the cue with the aversive stimulus. Administration of chlordiazepoxide\ud decreased movement activity during the CS, but not during the preCS. This finding suggests that contextual and classical conditioning are mediated by separate neuronal pathways, and that chlordiazepoxide appears to have a stronger effect in those brain regions involved with the processing of acute, phasic stimuli than on brain regions involved with contextual conditioning. The differential effect of chlordiazepoxide on specific limbic sites in this paradigm is also offered here