Brain Research, 297 (1984) 265-273 265 Elsevier Brain Stimulation Reward and Dopamine Terminal Fields. I. Caudate-Putamen, Nucleus Accumbens and Amygdala ROBERTO PRADO-ALCALA 1and ROY A. WISE 2 1Department of Physiology, School of Medicine National University of Mexico, Mexico, D.F. 04510 (Mexico) and 2Centerfor Studies in Behavioral Neurobiology, Department of Psychology Concordia University, Montreal, Quebec H3G 1M8 (Canada) (Accepted August 23rd, 1983) Key words: brain stimulation reward m dopamine terminals--caudate-putamen m nucleus accumbens m 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 ante- rior,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 fluo- rescence. 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 dopa- mine terminals or their efferent targets accounts for the rewarding quality of stimulation in these regions. INTRODUCTION Rewarding consequences of electrical brain stimu- lation are associated with each of the major regions of DA terminal innervation of the forebraina9,34, and DA receptor blockade attenuates the rewarding quality of stimulation13-17,45, at least in the case of some stimulation sites. It is thus of interest to deter- mine if the degree of reward associated with stimula- tion sites in different DA terminal fields bears any special relation to the degree of DA innervation at those sites. Such a relation seems not to hold in the case of the well-defined band of DA terminals in the septum31. In the striatum and associated DA termi- nal fields the DA innervation is not similarly hetero- geneous, but there remain variations which should predict reward strength if reward strength is propor- tional to the number of directly activated DA-inner- vated neurons or DA fiber terminals. In the present study a moveable electrode was used to map the caudate-putamen (CPU), nucleus accumbens septi (NAS), olfactory tubercle (OT) and central amygdaloid nucleus (AMY) for brain stimu- lation reward. Up to 11 sites were stimulated along a vertical penetration in each animal, and boundaries of the reward system were determined in relation to boundaries of the DA terminal fields as determined by fluorescence histochemistry. Density of DA in- nervation was rated at each stimulation site and cor- relations were determined between density of inner- vation and goodness of brain stimulation reward as reflected in several criterion variables. METHODS Experimentally naive male hooded rats weighing between 250 and 300 g were implanted with unipolar moveable electrodes 39. Stereotaxic coordinates were selected so as to include most of the CPU (A-P = --0.8 to 4.0, M-L = 1.5 to 5.4, D-V = 3.0 to 7.6), the NAS (2.0 to 4.0, 0.1 to 1.2, 2.8 to 6.0), the OT (3.0 to 4.2, 1.9 to 3.6, 5.5 to 8.2), and the AMY (---0.4 to 1.6, 4.0 to 5.0, 6.2 to 8.6), as determined from breg- ma (A-P = 0) and from the dural surface (D-V = Correspondence: R. A. Wise, Department of Psychology, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, P.Q., Canada H3G 1M8. 0006-8993/84/$03.00 © 1984 Elsevier Science Publishers B.V.