title: The cortical activation differences between proximal and distal joint movements of the upper extremities: a functional NIRS study.
abstract: OBJECTIVE
  Motor control of musculature of proximal and distal joints has been suggested to differ. However, no study comparing patterns of activation between movements of proximal and distal joints has been conducted. In this study, using functional near infrared spectroscopy (fNIRS), we attempted to compare patterns of cortical activation generated during movements of shoulder and hand.
  
  
  METHODS
  Nine normal subjects were recruited. fNIRS was performed using a fNIRS system with 49 channels. Flexion-extension movements of the right shoulder or hand were performed. We measured values of oxy-hemoglobin (HbO) and total-hemoglobin (HbT) in three regions of interest: the primary sensory-motor cortex (SM1), the premotor cortex (PMC), and the prefrontal cortex (PFC). The relative activation ratio of HbO and HbT was estimated for comparison of the relative activity of the left PMC or PFC to the left SM1.
  
  
  RESULTS
  Mean values of HbO and HbT of the left SM1, PMC, and PFC were higher during movements of the right shoulder, compared with movements of the left hand. Relative activation ratios for movements of the right shoulder (HbO: PMC-104.5%, PFC-110.9%; HbT: PMC-136.3%, PFC-200.1%) were greater than 100%, and, by contrast, less than 100% (HbO: PMC-57.5%, PFC-84.8%; HbT: PMC-88.9%, PFC-70.3%) for movements of the right hand.
  
  
  CONCLUSIONS
  Our results appear to indicate that movements of the shoulder require greater neural recruitment than movements of the hand. In addition, the PMC and PFC appeared to have greater involvement than the SM1 in movements of the shoulder; by contrast, the SM1 appears to have greater involvement than the PMC and PFC in movements of the hand.
authors.affiliation: Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Republic of Korea.
authors.forename: Sang Seok
authors.initials: SS
authors.lastname: Yeo
authors.forename: Pyung-Hun
authors.initials: PH
authors.lastname: Chang
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Jang
mesh_terms: D000328:Adult; D001931:Brain Mapping; D006225:Hand / Q000502:physiology; D006801:Humans; D007596:Joints / Q000502:physiology; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement; D017397:Prefrontal Cortex / Q000502:physiology*; D012782:Shoulder / Q000502:physiology; D019265:Spectroscopy, Near-Infrared; D034941:Upper Extremity / Q000502:physiology*