Neural projections from nucleus accumbens to globus pallidus, substantia innominata, and lateral preoptic-lateral hypothalamic area: an anatomical and electrophysiological investigation in the rat

Abstract

The anatomical organization and electrophysiological characteristics of a projection from the nucleus accumbens to anteroventral parts of the globus pallidus and to a subpallidal region that includes the substantia innominata (SI), the lateral preoptic area (LPO), and anterior parts of the lateral hypothalamic area (LHA) were investigated in the rat. Autoradiographic experiments, with injections of 3H-proline into different sites in the nucleus accumbens and adjacent caudoputamen, indicate that the descending fibers are organized topographically along both mediolateral and dorsoventral gradients, although labeled fibers from adjacent regions of the nucleus accumbens overlap considerably in the ventral globus pallidus and subpallidal region. Injections confined to the caudoputaman only labeled fibers in the globus pallidus. Retrograde transport experiments with the marker true blue confirmed that only the nucleus accumbens projects to the subpallidal region and that the caudoputamen projects upon the glubus pallidus in a topographically organized manner. In electrophysiological recording experiments single pulse stimulation (0.1 to 0.7 mA; 0.15 msec duration) of the nucleus accumbens changed the discharge rate of single neurons in the ventral globus pallidus and in the SI, LPO, and LHA. Typically, the responses were inhibition of neuronal discharge with latencies of 6 to 18 msec. Single pulse stimulation of the dorsolateral caudoputamen altered the discharge rate of single neurons in dorsal regions of the globus pallidus, with inhibition being the most frequently observed response. The results of these anatomical and electrophysiological experiments are complementary and indicate that fibers from the nucleus accumbens innervate the anteroventral region of the globus pallidus as well as the subpallidal region, while most fibers of the caudoputamen innervate the globus pallidus but not the subpallidal region. It appears, therefore, that these two components of the striatum have different output connections. The possible functional significance of these findings is discussed in relation to the projections of the subpallidal region, which may include an output to the mesencephalic locomotor region, and in relation to the nucleus accumbens afferents from the amygdala and hippocampal formation.

Activation of Group II Metabotropic Glutamate Receptors Inhibits the Discriminative Stimulus Effects of Alcohol via Selective Activity Within the Amygdala

“…These results are in contrast to the significant motor impairment evident following intraaccumbens administration of LY379268, suggesting dissociation between global glutamatergic pathways or neural circuits that may be affected following systemically and those specifically altered following intra-accumbens administration of the mGlu2/3 receptor agonist. In addition, this differential sensitivity to the motor impairment following systemic and local administration of LY379268 and that of the nucleus accumbens and the amygdala may be attributable to reduced activity from nucleus accumbens efferent projections to the globus pallidus, a key neuroanatomical structure for coordinated locomotor function (Mogenson et al, 1983).…”

Neuroelectric Signatures of Reward Learning and Decision-Making in the Human Nucleus Accumbens

“…One possibility is the mediodorsal nuclei of the thalamus, which projects to both structures (Berendse and Groenewegen, 1990), and which is necessary for some reward-related behavior adaptations (Block et al, 2007). Another possible route is through the midbrain dopamine centers, which receive projections from the nucleus accumbens (via the globus pallidus) and project back to medial frontal cortex (Powell and Leman, 1976;Mogenson et al, 1983;Haber and McFarland, 1999).…”

Activation of Glutamate Neurotransmission in the Prefrontal Cortex Sustains the Motoric and Dopaminergic Effects of Phencyclidine

“…For example, the temporal profiles of dopamine release and motor activation are dissociated Kretschmer, 2000) and, more importantly, NMDA antagonists produce hyperlocomotion after lesions of dopamine pathways to the NAc (Carlsson and Carlsson, 1989). Considering the profound stimulatory effect of NMDA antagonists on PFC activity in rats (Moghaddam et al, 1997) and humans (Lahti et al, 1995), and the fact that PFC glutamatergic efferents directly innervate regions such as the ventral tegmental area (VTA) that are connected to motor effector sites (Mogensen et al, 1983;Sesack et al, 1989;Groenewegen and Uylings, 2000), we hypothesized that NMDA antagonist-induced increase in PFC activity, in addition to producing the cognitive abnormalities, also underlies the motoric effects of these drugs, independent of NAc dopamine activation.…”