Efferent connections of the ventral pallidum: Evidence of a dual striato pallidofugal pathway

Abstract

Previous histological and histochemical studies have provided evidence that the globus pallidus (external pallidal segment) as conventionally delineated in the rat extends ventrally and rostrally beneath the transverse limb of the anterior commissure, invading the olfactory tubercle with its most ventral ramifications. This infracommissural subdivision of the globus pallidus or ventral pallidum (VP) is most selectively identified by being pervaded by a dense plexus of substance-P-positive striatofugal fibers; the extent of this plexus indicates that the VP behind the anterior commissure continues dorsally over some distance into the anteroventromedial part of the generally recognized (supracommissural) globus pallidus; the adjoining anterodorsolateral pallidal region, here named dorsal pallidum (DP), receives only few substance-P-positive fibers, but contains a dense plexus of enkephalin-positive striatal afferents that also pervades VP. Available autoradiographic data indicate that VP and DP receive their striatal innervation from two different subdivisions of the striatum: whereas VP is innervated by a large, anteroventromedial striatal region receiving substantial inputs from a variety of limbic and limbic-system-associated structures (and therefore called "limbic striatum"), DP receives its striatal input from an anterodorsolateral striatal sector receiving only sparse limbic afferents ("nonlimbic" striatum) but instead heavily innervated by the sensorimotor cortex. The present autoradiographic study has produced evidence that this dichotomy in the striatopallidal projection is to a large extent continued beyond the globus pallidus: whereas the efferents of DP were traced to the subthalamic nucleus and substantia nigra, those of VP were found to involve not only the subthalamic nucleus and substantia nigra but also the frontocingulate (and adjoining medial sensorimotor) cortex, the amygdala, lateral habenular and mediodorsal thalamic nucleus, hypothalamus, ventral tegmental area, and tegmental regions farther caudal and dorsal in the midbrain. These findings indicate that the ventral pallidum can convey striatopallidal outflow of limbic antecedents not only into extrapyramidal circuits but also back into the circuitry of the limbic system.

Distribution of Dopamine D3 Receptor Expressing Neurons in the Human Forebrain Comparison with D2 Receptor Expressing Neurons

“…Additional sources of input to the limbic striatum include regions enriched in D 3 receptors such as the anterior nuclei of the thalamus and NBM. The ventral striatum projects primarily to the VP, the most medial part of the GPi and SNr (Haber et al 1985;Lynd-Balta and Haber 1994a), which are also enriched with D 3 receptors and D 3 mRNA positive neurons. These regions provide input to the anterior nuclei of the thalamus (Groenewegen et al 1990).…”

“…In agreement with previous reports, we found that the D 2 receptors and mRNA were the most abundant in the dorsal CN and Pu (Joyce et al 1991;Huntley et al 1992;Murray et al 1994;Meador-Woodruff et al 1996), whereas D 3 receptor sites and mRNA were enriched in the ventral Pu and NAC, often in dense patches of binding and clusters of D 3 mRNA positive neurons, (Landwehrmeyer et al 1993;Herroelen et al 1994;Murray et al 1994;Meador-Woodruff et al 1996;Gurevich et al 1997;Suzuki et al 1998). NAC, which has the highest D 3 receptor concentration and number of D 3 mRNA positive neurons of all brain areas, projects primarily to the VP, medial part of the GPi and SNr (Haber et al 1985;Haber 1994a, 1994b), all regions enriched with the D 3 receptor and D 3 mRNA positive neurons. This is interesting, because cell morphology, connections, and neurochemical and physiological characteristics of the GPi and SNr are very similar Yelnik et al 1987).…”

AAV2-mediated CLN2 gene transfer to rodent and non-human primate brain results in long-term TPP-I expression compatible with therapy for LINCL

“…Neurons in both the dorsal and ventral striatum receive input from cerebral cortex, thalamus, and the midbrain ventral tegmental area and substantia nigra. [39][40][41] Thus, distant neurons, whose axons terminate in the region of vector delivery, were able over time to express TPP-I. There are two possible explanations for TPP-I expression in distant projection neurons.…”

The Functional Neuroanatomy of Tourette's Syndrome: An FDG-PET Study. I. Regional Changes in Cerebral Glucose Metabolism Differentiating Patients and Controls

“…It is the principal site in which information from limbic structures gains access to the motor system (Mogenson 1987;Heimer et al 1982) in part via inter actions with dorsal elements of the core nuclei of the basal ganglia (Haber et al 1985(Haber et al , 1990 . If functional changes in paralimbic regions are linked to changes in the frontal motor cortices in the TS brain, projections through the ventral striatum may be the most direct route through which such coupling might occur.…”