Section 1.1, describes the basic anatomy of midbrain dopamine (DA) system. Due to the heterogeneous nature and wide projection, I have summarized the essential points in this section. Section 1.2 focuses on the role of DA for motivated behaviour and change in the striatum during learning is in order, hence the DA role can be made clear. The chapter focuses on nucleus accumbens (NAc) DA changes due to the massive projection from ventral tegmental area(VTA). Special emphasis is given to the DA role in reward processing and avoidance learning. Section 1.3 starts with the history of intracranial self-stimulation (ICSS) and explains the mechanisms of ICSS which was used extensively in my research. Also, it adds insight to the ICSS behaviour supported by different brain systems and the underlying mechanisms. Section 1.4, reviews studies that have addressed the interaction of appetitive reward and aversive punishment. Since DA plays vital role in pain avoidance and reward seeking, I outlined the questions answered by the present study using VTA stimulation. The methods part describes experiment details and explains training procedures for different groups and experimental manipulations.