Highly overlapping structures are also identified for pain processing (Gauriau and Bernard, 2002; Saper, 2002). Autonomic and motor responses are tightly coupled to rewarding as well as aversive

events (and their expectations) or the saliency of sensory cues. In this sense, efferent copies of autonomic or motor signals may serve as a surrogate of important information for dopamine neurons, such as reward expectation and motivational saliency, in addition to general states of the animal. Although the role of these motor and autonomic inputs in the regulation of dopamine neuron activities is unclear, RG7204 cell line our finding provides a framework with which to explore the mechanisms of dopamine neuron regulation. It has been proposed that PTg plays an important role in reward prediction error computations PD0332991 order (Kawato and Samejima, 2007; Okada et al., 2009).

Previous studies have shown that electrical stimulation of PTg produced monosynaptic activation of dopamine neurons (Futami et al., 1995; Lokwan et al., 1999; Scarnati et al., 1984). Some anatomical studies have also indicated that PTg projects to both VTA and SNc using anterograde and retrograde tracing methods (Jackson and Crossman, 1983; Oakman et al., 1995; Zahm et al., 2011). These results appear to differ from our data indicating relatively sparse labeling of PTg from the VTA compared to SNc dopamine neurons. This difference may be explained if single PTg neurons make many synapses onto VTA dopamine neurons or synapses transmissions are strong. The aforementioned results may also be confounded by nonspecific electrical stimulation of passing fibers or uptake of tracers. Whether VTA receives strong direct inputs from PTg neurons remains to be clarified. Our method allowed us to avoid limitations of previous methods (i.e., cell-type specificity and labeling axons of passage), and the difference from

other studies may come, at least in part, from the Beta Amyloid specificity achieved using our method although the exact reasons need to be clarified in the future. It should also be noted that other anatomical studies have indicated that VTA does not receive strong inputs from PTg (Geisler and Zahm, 2005; Phillipson, 1979). Degeneration of SNc dopamine neurons leads to the severe motor impairments of Parkinson’s disease. Symptoms of this disease can be ameliorated by high-frequency electrical stimulation of specific brain areas (deep brain stimulation [DBS]) (Benabid et al., 2009; Wichmann and Delong, 2006). Despite the wide use and success of DBS, its mechanisms remain highly debated, and it is unknown why specific targets are more effective than others. The most popular target of DBS is the STh. As described earlier, we found relatively strong direct projections from the STh to SNc dopamine neurons.