Available evidence suggests that PD and DLB are associated with distinct patterns of functional network dysfunction, namely increased basal ganglia-thalamocortical connectivity in PD and reduced global and local cortico-cortical connectivity in patients with dementia. The basal ganglia-thalamocortical loop includes the striatum, globus pallidus, thalamus, subthalamic nucleus, and substantia nigra; and cortical motor areas (primary motor cortex, supplementary motor area, premotor cortex).94 Resting-state fMRI studies of this network have consistently reported increased connectivity between the basal ganglia and motor regions in PD patients.95-98 These network abnormalities were normalised after levodopa administration.95,98 In addition, reduced connectivity within this network has been reported by resting-state fMRI studies between the putamen and parietal and motor areas.95,96 Resting-state EEG/MEG studies reported increased connectivity in the alpha and beta (8-30 Hz) frequency ranges, between the subthalamic nucleus and the motor cortex,99 and cortico-cortically.100 A resting-state MEG study of patients in early, drug-naive stages showed an increase in alpha band (8-10 Hz) cortico-cortical functional connectivity that expanded toward other frequency bands (4-30 Hz range) with increasing disease severity.101 Increased connectivity affected both global and local connections and
