title: Convergent inputs from thalamic motor nuclei and frontal cortical areas to the dorsal striatum in the primate.
abstract: Current models of basal ganglia circuitry primarily associate the ventral thalamic nuclei with relaying basal ganglia output to the frontal cortex. However, some studies have demonstrated projections from the ventral anterior (VA) and ventral lateral (VL) thalamic nuclei to the striatum, suggesting that these nuclei directly modulate the striatum. VA/VL nuclei have specific connections with primary, supplementary, premotor, and cingulate motor cortices indicating their involvement in motor function. These areas mediate different aspects of motor control such as movement execution, motor learning, and sensorimotor integration. Increasing evidence indicates that functionally related motor areas have convergent projections to the dorsal striatum, suggesting that integration of different aspects of motor control occur at the level of the striatum. This study examines the organization of VA/VL thalamic inputs to the dorsal "motor" striatum to determine how this afferent projection is organized with respect to corticostriatal afferents from motor, premotor, and cingulate motor areas. Motor cortical projections to specific dorsal striatal regions arose from multiple areas, including components from primary motor, premotor, supplementary, and cingulate motor areas. Diverse motor cortical projections to a given dorsal striatal region indicated convergence of functionally related corticostriatal motor pathways. Most dorsal striatal sites received dense thalamic inputs from the VL pars oralis nucleus. Additional thalamostriatal projections arose from VA, VL pars caudalis, and ventral posterior lateral pars oralis nuclei and Olszewski's Area X. Our results provide evidence for convergent striatal projections from interconnected ventral thalamic and cortical motor areas, suggesting that these afferents modulate the same striatal output circuits.
authors.affiliation: Department of Neurobiology and Anatomy, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
authors.forename: N R
authors.initials: NR
authors.lastname: McFarland
authors.forename: S N
authors.initials: SN
authors.lastname: Haber
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes; D006179:Gyrus Cinguli / Q000166:cytology; D007546:Isoquinolines; D008253:Macaca mulatta; D008254:Macaca nemestrina; D009044:Motor Cortex / Q000166:cytology*; D009046:Motor Neurons / Q000166:cytology; D017072:Neostriatum / Q000166:cytology*; D009434:Neural Pathways; D020651:Ventral Thalamic Nuclei / Q000166:cytology*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
chemical_list: D005456:Fluorescent Dyes; D007546:Isoquinolines; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; C017475:lucifer yellow