Brain stimulation reward and dopamine terminal fields. I. Caudate-putamen, nucleus accumbens and amygdala

The boundaries and relative sensitivity of brain stimulation reward were mapped in relation to the dopamine (DA) terminal fields of the striatum and adjacent limbic structures. Brain stimulation was rewarding throughout the caudate and nucleus accumbens and in portions of the amygdala and olfactory tubercle. The best striatal sites were anterior, ventral and medial; this correlated with an anterior-posterior gradient but not with a dorsal-ventral or a medial-lateral gradient of DA terminal density. No close correspondence was seen between the boundaries of the reward system and those of the DA terminal fields as revealed by glyoxylic acid-induced DA fluorescence. Reward sites in the olfactory tubercle and amygdala were found in DA-free as well as DA-rich regions of these structures; stimulation in DA-rich regions did not always support self-stimulation. These data go against the view that direct activation of dopamine terminals or their efferent targets accounts for the rewarding quality of stimulation in these regions.