Open Access

Tauqeer Anjum, Jan Raethjen, Hao Ding, Nabin Koirala, Rüdiger Pryss, Robin Wolke, Chi Wang Ip, Günther Deuschl, Jens Volkmann, Nils G. Margraf, Muthuraman Muthuraman

• Background Studies on brain connectivity offer important insights into the changes that occur in central network diseases such as Parkinson's disease (PD). Camptocormia, a condition characterized by abnormal flexion of the trunk, often occurs in advanced PD, but its underlying mechanisms are not yet clear. Objective This study aims to investigate the changes in the central motor network, associated with camptocormia. Methods High-density 256-channel electroencephalography (EEG) and multichannel electromyography (EMG) recordings from the paravertebral lumbar (PVL) muscles were obtained. Tomographic maps of EEG–EMG coherence were obtained using a beamformer algorithm based on individual β frequencies. We employed temporal partial directed coherence analyses to estimate the direction of information flow between coherent sources. Results In all patients and healthy controls, we found a widespread central network that showed coherence with PVL muscles and consisted of corticalBackground Studies on brain connectivity offer important insights into the changes that occur in central network diseases such as Parkinson's disease (PD). Camptocormia, a condition characterized by abnormal flexion of the trunk, often occurs in advanced PD, but its underlying mechanisms are not yet clear. Objective This study aims to investigate the changes in the central motor network, associated with camptocormia. Methods High-density 256-channel electroencephalography (EEG) and multichannel electromyography (EMG) recordings from the paravertebral lumbar (PVL) muscles were obtained. Tomographic maps of EEG–EMG coherence were obtained using a beamformer algorithm based on individual β frequencies. We employed temporal partial directed coherence analyses to estimate the direction of information flow between coherent sources. Results In all patients and healthy controls, we found a widespread central network that showed coherence with PVL muscles and consisted of cortical and subcortical regions mostly with mutual interactions on the central level and with the paravertebral muscles. In camptocormia patients, there was a significantly stronger coherence between the cortical and muscle activity than in PD without camptocormia patients. Brainstem activation was absent in camptocormia patients, whereas in PD without camptocormia patients, coherent activation in the posterior parietal cortex was missing. Conclusion Increased central muscle drive to the paravertebral muscles in camptocormia patients may indicate a relatively simple compensatory strategy to overcome stooped posture, whereas the decreased interaction strength between the central coherent sources and the lack of brainstem involvement likely reflects the primary deficits in central postural control network, likely promoting the defective postural motor pattern in camptocormia. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.…