Temporal dynamics of DA neuron activity in response to 1 µM nicotine for 2 min for different values of <i>r</i> and afferent input strengths.

<p>(A) The DA response in the presence of constant low cholinergic and glutamatergic afferent input to the VTA, <i>i.e.</i>, <i>in vitro</i> like conditions ( µM,). (B) The DA response in the presence of constant high cholinergic and glutamatergic afferent input to the VTA, <i>i.e.</i>, <i>in vivo</i> like conditions ( µM, ). In both panels, the distribution of α4β2 nAChRs is changed by varying the control parameter <i>r</i> in steps of 0.2 from 0 to 1 (as indicated). The examples with values of <i>r</i> as used for the direct stimulation (, red) and disinhibition (, blue) cases in this study are highlighted.