title: Dopaminergic basis for impairments in functional connectivity across subdivisions of the striatum in Parkinson's disease.
abstract: The pathological hallmark of Parkinson's disease is the degeneration of dopaminergic nigrostriatal neurons, leading to depletion of striatal dopamine. Recent neuroanatomical work has identified pathways for communication across striatal subdivisions, suggesting that the striatum provides a platform for integration of information across parallel corticostriatal circuits. The aim of this study was to investigate whether dopaminergic dysfunction in Parkinson's disease was associated with impairments in functional connectivity across striatal subdivisions, which could potentially reflect reduced integration across corticostriatal circuits. Utilizing resting-state functional magnetic resonance imaging (fMRI), we analyzed functional connectivity in 39 patients with Parkinson's disease, both "on" and "off" their regular dopaminergic medications, along with 40 age-matched healthy controls. Our results demonstrate widespread impairments in connectivity across subdivisions of the striatum in patients with Parkinson's disease in the "off" state. The administration of dopaminergic medication significantly improved connectivity across striatal subdivisions in Parkinson's disease, implicating dopaminergic deficits in the pathogenesis of impaired striatal interconnectivity. In addition, impaired striatal interconnectivity in the Parkinson's disease "off" state was associated with pathological decoupling of the striatum from the thalamic and sensorimotor (SM) networks. Specifically, we found that although the strength of striatal interconnectivity was positively correlated with both (i) the strength of internal thalamic connectivity, and (ii) the strength of internal SM connectivity, in both healthy controls and the Parkinson's disease "on" state, these relationships were absent in Parkinson's disease when in the "off" state. Taken together our findings emphasize the central role of dopamine in integrated striatal function and the pathological consequences of striatal dopamine denervation in Parkinson's disease.
authors.affiliation: Brain and Mind Research Institute, The University of Sydney, Sydney, NSW, Australia; University of Queensland Centre for Clinical Research, University of Queensland, Brisbane, QLD, Australia.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Bell
authors.forename: Moran
authors.initials: M
authors.lastname: Gilat
authors.forename: Claire
authors.initials: C
authors.lastname: O'Callaghan
authors.forename: David A
authors.initials: DA
authors.lastname: Copland
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Frank
authors.forename: Simon J G
authors.initials: SJ
authors.lastname: Lewis
authors.forename: James M
authors.initials: JM
authors.lastname: Shine
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D001931:Brain Mapping; D003342:Corpus Striatum / Q000187:drug effects* / Q000503:physiopathology*; D004298:Dopamine / Q000378:metabolism; D015259:Dopamine Agents / Q000627:therapeutic use*; D005260:Female; D019416:Head Movements; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D012146:Rest; D012815:Signal Processing, Computer-Assisted; D013788:Thalamus / Q000187:drug effects / Q000503:physiopathology
chemical_list: D000978:Antiparkinson Agents; D015259:Dopamine Agents; D004298:Dopamine
keywords: Parkinson's disease; connectivity; dopamine; network; resting-state; striatum; subcortex; thalamus