title: Direct and indirect pathways of basal ganglia: a critical reappraisal.
abstract: The basal ganglia are subcortical nuclei controlling voluntary actions and have been implicated in Parkinson's disease (PD). The prevailing model of basal ganglia function states that two circuits, the direct and indirect pathways, originate from distinct populations of striatal medium spiny neurons (MSNs) and project to different output structures. These circuits are believed to have opposite effects on movement. Specifically, the activity of direct pathway MSNs is postulated to promote movement, whereas the activation of indirect pathway MSNs is hypothesized to inhibit it. Recent findings have revealed that this model might not fully account for the concurrent activation of both pathways during movement. Accordingly, we propose a model in which intrastriatal connections are critical and the two pathways are structurally and functionally intertwined. Thus, all MSNs might either facilitate or inhibit movement depending on the form of synaptic plasticity expressed at a certain moment. In PD, alterations of dopamine-dependent synaptic plasticity could alter this coordinated activity.
authors: 1] Clinica Neurologica, Dipartimento di Medicina, Università degli Studi di Perugia, Ospedale Santa Maria della Misericordia, S. Andrea delle Fratte, Perugia, Italy. [2] Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome, Italy.
authors: Paolo
authors: P
authors: Calabresi
authors: Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome, Italy.
authors: Barbara
authors: B
authors: Picconi
authors: 1] Clinica Neurologica, Dipartimento di Medicina, Università degli Studi di Perugia, Ospedale Santa Maria della Misericordia, S. Andrea delle Fratte, Perugia, Italy. [2] Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome, Italy.
authors: Alessandro
authors: A
authors: Tozzi
authors: Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome, Italy.
authors: Veronica
authors: V
authors: Ghiglieri
authors: Clinica Neurologica, Dipartimento di Medicina, Università degli Studi di Perugia, Ospedale Santa Maria della Misericordia, S. Andrea delle Fratte, Perugia, Italy.
authors: Massimiliano
authors: M
authors: Di Filippo
mesh_terms: D000818:Animals; D001479:Basal Ganglia / Q000166:cytology / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000502:physiology*