title: Involvement of the basal ganglia and cerebellar motor pathways in the preparation of self-initiated and externally triggered movements in humans.
abstract: The subthalamic nucleus (STN) is part of the cortico-basal ganglia (BG)-thalamocortical circuit, whereas the ventral lateral nucleus of the thalamus (VL) is a relay nucleus in the cerebello-dentato-thalamocortical (CTC) pathway. Both pathways have been implicated in movement preparation. We compared the involvement of the STN and VL in movement preparation in humans by recording local field potentials (LFPs) from seven patients with Parkinson's disease with deep-brain stimulation (DBS) electrodes in the STN and five patients with tremor and electrodes in VL. LFPs were recorded from DBS electrodes and scalp electrodes simultaneously while the patients performed self-paced and externally cued (ready, go/no-go) movements. For the self-paced movement, a premovement-related potential was observed in all patients from scalp, STN (phase reversal, five of six patients), and VL (phase reversal, five of five patients) electrodes. The onset times of the potentials were similar in the cortex, STN, and VL, ranging from 1.5 to 2 s before electromyogram onset. For the externally cued movement, an expectancy potential was observed in all patients in cortical and STN electrodes (phase reversal, six of six patients). The expectancy potential was recorded from the thalamic electrodes in four of five patients. However, phase reversal occurred only in one case, and magnetic resonance imaging showed that this contact was outside the VL. The cortico-BG-thalamocortical circuit is involved in the preparation of both self-paced and externally cued movements. The CTC pathway is involved in the preparation of self-paced but not externally cued movements, although the pathway may still be involved in the execution of these movements.
authors.affiliation: The Krembil Neuroscience Centre and Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.
authors.forename: Jamie
authors.initials: J
authors.lastname: Purzner
authors.forename: Guillermo O
authors.initials: GO
authors.lastname: Paradiso
authors.forename: Danny
authors.initials: D
authors.lastname: Cunic
authors.forename: Jean A
authors.initials: JA
authors.lastname: Saint-Cyr
authors.forename: Tasnuva
authors.initials: T
authors.lastname: Hoque
authors.forename: Andres M
authors.initials: AM
authors.lastname: Lozano
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Lang
authors.forename: Elena
authors.initials: E
authors.lastname: Moro
authors.forename: Mojgan
authors.initials: M
authors.lastname: Hodaie
authors.forename: Filomena
authors.initials: F
authors.lastname: Mazzella
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D001479:Basal Ganglia / Q000502:physiology*; D002531:Cerebellum / Q000502:physiology*; D003463:Cues; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009042:Motivation; D009068:Movement / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology; D014202:Tremor / Q000503:physiopathology