title: The role of the human globus pallidus in Huntington's disease.
abstract: Huntington's disease (HD) is characterized by pronounced pathology of the basal ganglia, with numerous studies documenting the pattern of striatal neurodegeneration in the human brain. However, a principle target of striatal outflow, the globus pallidus (GP), has received limited attention in comparison, despite being a core component of the basal ganglia. The external segment (GPe) is a major output of the dorsal striatum, connecting widely to other basal ganglia nuclei via the indirect motor pathway. The internal segment (GPi) is a final output station of both the direct and indirect motor pathways of the basal ganglia. The ventral pallidum (VP), in contrast, is a primary output of the limbic ventral striatum. Currently, there is a lack of consensus in the literature regarding the extent of GPe and GPi neurodegeneration in HD, with a conflict between pallidal neurons being preserved, and pallidal neurons being lost. In addition, no current evidence considers the fate of the VP in HD, despite it being a key structure involved in reward and motivation. Understanding the involvement of these structures in HD will help to determine their involvement in basal ganglia pathway dysfunction in the disease. A clear understanding of the impact of striatal projection loss on the main neurons that receive striatal input, the pallidal neurons, will aid in the understanding of disease pathogenesis. In addition, a clearer picture of pallidal involvement in HD may contribute to providing a morphological basis to the considerable variability in the types of motor, behavioral, and cognitive symptoms in HD. This review aims to highlight the importance of the globus pallidus, a critical component of the cortical-basal ganglia circuits, and its role in the pathogenesis of HD. This review also summarizes the current literature relating to human studies of the globus pallidus in HD.
authors.affiliation: Centre for Brain Research, University of Auckland, Auckland, New Zealand.|Department of Anatomy with Medical Imaging, University of Auckland, Auckland, New Zealand.
authors.forename: Malvindar K
authors.initials: MK
authors.lastname: Singh-Bains
authors.affiliation: Centre for Brain Research, University of Auckland, Auckland, New Zealand.|Department of Anatomy with Medical Imaging, University of Auckland, Auckland, New Zealand.
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Waldvogel
authors.affiliation: Centre for Brain Research, University of Auckland, Auckland, New Zealand.|Department of Anatomy with Medical Imaging, University of Auckland, Auckland, New Zealand.
authors.forename: Richard L M
authors.initials: RL
authors.lastname: Faull
mesh_terms: D002540:Cerebral Cortex / Q000473:pathology; D005917:Globus Pallidus / Q000473:pathology* / Q000502:physiology*; D006801:Humans; D006816:Huntington Disease / Q000473:pathology*; D009434:Neural Pathways / Q000502:physiology
keywords: Huntington's disease; basal ganglia; globus pallidus externus; globus pallidus internus; ventral pallidum