Contributions of dopaminergic and non-dopaminergic neurons to VTA-stimulation induced neurovascular responses in brain reward circuits

Publication date: 15 August 2018 Source:NeuroImage, Volume 177 Author(s): Marta Brocka, Cornelia Helbing, Daniel Vincenz, Thomas Scherf, Dirk Montag, Jürgen Goldschmidt, Frank Angenstein, Michael Lippert Mapping the activity of the human mesolimbic dopamine system by BOLD-fMRI is a tempting approach to non-invasively study the action of the brain reward system during different experimental conditions. However, the contribution of dopamine release to the BOLD signal is disputed. To assign the actual contribution of dopaminergic and non-dopaminergic VTA neurons to the formation of BOLD responses in target regions of the mesolimbic system, we used two optogenetic approaches in rats. We either activated VTA dopaminergic neurons selectively, or dopaminergic and mainly glutamatergic projecting neurons together. We further used electrical stimulation to non-selectively activate neurons in the VTA. All three stimulation conditions effectively activated the mesolimbic dopaminergic system and triggered dopamine releases into the NAcc as measured by in vivo fast-scan cyclic voltammetry. Furthermore, both optogenetic stimulation paradigms led to indistinguishable self-stimulation behavior. In contrast to these similarities, however, the BOLD response pattern differed greatly between groups. In general, BOLD responses were weaker and sparser with increasing stimulation specificity for dopaminergic neurons. In addition, repetitive stimulation of the VTA caused a progressive deco...

Source: NeuroImage - May 17, 2018 Category: Neuroscience Source Type: research