The conceptualization of emotions as discrete and independent has arisen largely from affective research with animals. By selectively stimulating neural pathways and observing subsequent behaviours, or conversely by eliciting behaviours in highly constrained experimental circumstances and measuring neural activity, animal researchers have constructed taxonomies of the basic emotions and proposed specific neural pathways associated with each putative basic emotion (Panksepp, 1998). In this paper we describe some of the methods used for the study of cognitive and affective processes in rats and also an experimental situation involving the right-unilateral 6-hydroxydopamine (6- OHDA) lesion (8µg/3µl and 16µg/3µl) of the paraventricular nucleus (PVN), which significantly diminished anxiety state, in a dose-dependent manner and affected the cognitive processes.