Functional brain networks in Parkinson's disease

With the advent of new methods of network analysis, we have utilized metabo lic data acquired through positron emission tomography (PET) to identify di sease-related patterns of functional pathology in the movement disorders. I n Parkinson's disease (PD), we have used [F-18]-fluorodeoxyglucose (FDG)/PE T to identify a disease-related regional metabolic covariance pattern chara cterized by lentiform and thalamic hypermetabolism associated with regional metabolic decrements in the lateral premotor cortex, the supplementary mot or area, the dorsolateral prefrontal cortex, and the parieto-occipital asso ciation regions. The expression of this network is modulated in a predictab le fashion by levodopa therapy and by stereotaxic interventions for PD. We have extended this network analytical approach from studies of glucose m etabolism in the resting state to dynamic studies of brain activation durin g motor performance. These PET studies utilized [O-15] -water (H-2 O-15) to measure cerebral blood flow activation responses during the execution of s imple and complex motor tasks. In addition to the modulation of abnormal re sting metabolic networks, effective PD therapy can enhance brain activation responses during motor execution, with specific regional associations with improvements in timing and spatial accuracy. This approach is also useful in identifying specific brain networks mediati ng the learning of sequential information. We have found that the normal re lationship between brain networks and learning performance are altered in t he earliest stages of PD with a functional shift from striatal to cortical processing. Brain activation PET studies during therapeutic interventions f or PD demonstrate how normal brain-behavior relationships can be restored w ith successful therapy. Thus, functional brain imaging with network analysi s can provide insights into the mechanistic basis of basal ganglia disorder s and their treatment. (C) 2001 Elsevier Science Ltd. All rights reserved.