Dopamine release in response to unconditioned and conditioned aversive stimuli

Abstract

Event Abstract Back to Event Dopamine release in response to unconditioned and conditioned aversive stimuli Andrew M. Young1* 1 University of Leicester, School of Psychology, United Kingdom Many studies, mainly using brain microdialysis, have reported increases in dopamine release in nucleus accumbens during presentation of aversive stimuli, such as tail pinch, mild foot shock, and restraint. Moreover, neutral stimuli such as tone, also evoke dopamine release in this brain region when they predict the onset of an aversive stimulus, by virtue of having previously been conditioned, but not when they are unconditioned [3,4]. However, the temporal and spatial resolution offered by microdialysis, even with 1 minute sampling [3], make it difficult to draw conclusions about the specific role of dopamine in these situations.Fast cyclic voltammetry (FCV) measures the oxidation of dopamine at a carbon fibre microelectrode implanted in brain tissue. Initial studies used anaesthetized animals, or brain slice preparations [2], but recent technical developments have enabled FCV to be implemented in conscious, freely moving animals [1,3]. We are therefore now able to measurement dopamine in very localized brain areas, at sub-second time resolution, in behaving animals. We have used FCV in freely moving rats to measure dopamine release during the presentation of unconditioned and conditioned aversive stimuli. These include mild footshock, a neutral low intensity tone stimulus, the same low intensity tone stimulus rendered motivationally salient, by virtue of having previously been paired with footshock in a conditioning procedure, and an intrinsically aversive (high intensity) tone. The results enable us to understand better the role of dopamine in responses to motivational and non-motivational stimuli.