Response competition between sucrose dish approach and lever pressing. A. Averaged time-course of approach responses to sucrose dish just before, during and after first CS+ cue presentation. B. Same information for pressing on sucrose-associated lever. Each panel compares cue-triggered responding after microinjections of vehicle (white circles), CRF 500 μg (green circles), CRF 250 μg (blue circles), or amphetamine 20 μg (red circles). Both CRF and amphetamine reduced the peak of cue-triggered approaches to the sucrose dish, but simultaneously increased cue-triggered lever pressing. It is impossible to perform both actions at exactly the same time, and so conditioned dish approaches may have been suppressed as a result of response competition from increased lever pressing that occurred during the same 30-sec period.
Peciña et al. BMC Biology 2006 4:8 doi:10.1186/1741-7007-4-8