Dopamine depletion in Parkinson’s disease (PD) reduces topological efficiency of the cortico-basal ganglia (CBG) motor circuit, according to a study published in PLoS ONE.
In PD, the degeneration of dopaminergic neurons in substantia nigra pars compacta is thought to cause abnormal modulation of CBG circuits. Other PD neuroimaging studies have observed functional and anatomical alterations in the CBG motor pathway, but no study had targeted topological changes.
The researchers used resting-state fMRI (rs-fMRI) and graph theoretical approach to study the topological efficiency changes of the CBG motor network in 37 PD patients during a relatively hypodopaminergic state, 12 hours after their last dose of dopaminergic medication. Only mild to moderate stage patients took part in the study.
Compared with healthy controls, PD patients showed slightly decreased (FDR correction, p<0.05) efficiency in the CBG motor network, especially the reduced nodal efficiency in the left SMA-proper, right pre-SMA, and bilateral M1, postcentral gyrus (S1), THA, PUT, and GP. Additionally, correlation analysis showed a significant, negative relationship between reduced efficiency of the right pre-SMA, left M1, bilateral GP, and bilateral THA brain areas and UPDRS motor score.
These results suggest that reduced efficiency in particular brain areas upsets the balance of information transmission in the CBG motor loop. Researchers also believe that network efficiency metrics provide a useful way to study the pathophysiology of PD.
Parkinson’s disease is mainly characterized by dopamine depletion of the cortico-basal ganglia (CBG) motor circuit. Given that dopamine dysfunction could affect functional brain network efficiency, the present study utilized resting-state fMRI (rs-fMRI) and graph theoretical approach to study the topological efficiency changes of the CBG motor network in patients with mild to moderate Parkinson’s disease.