ABSTRACT
Movement and muscle control are crucial for the survival of all free-living organisms. This study aimed to explore differential patterns of cortical and subcortical activation across different stages of muscle control using functional magnetic resonance imaging (fMRI). An event-related design was employed. In each trial, participants (n = 10) were instructed to gently press a button with their right index finger, hold it naturally for several seconds, and then relax the finger. Neural activation in these temporally separated stages was analyzed using a General Linear Model. Our findings revealed that a widely distributed cortical network, including the supplementary motor area and insula, was implicated not only in the pressing stage, but also in the relaxation stage, while only parts of the network were involved in the steady holding stage. Moreover, supporting the direct/indirect pathway model of the subcortical basal ganglia, their substructures played distinct roles in different stages of muscle control. The caudate nucleus exhibited greater involvement in muscle contraction, whereas the putamen demonstrated a stronger association with muscle relaxation; both structures were implicated in the pressing stage. Furthermore, the subthalamic nucleus was exclusively engaged during the muscle relaxation stage. We conclude that even the control of simple muscle movements involves intricate automatic higher sensory-motor integration at a neural level, particularly when coordinating relative muscle movements, including both muscle contraction and muscle relaxation; the cortical and subcortical regions assume distinct yet coordinated roles across different stages of muscle control.
ABSTRACT
Objective To explore the mechanism of deep brain stimulation(DBS)therapy to Parkinson's disease(PD).Methods We produced hemi-parkinsonian rat model with stereotaxically injecting 6-OHDA to right medial forebrain bundle(MFB)and stimulated ipsilateral subthalamu nucleus (STN)with platinum electrodes chronically to investigate the influence of DBS to the expression of Calbindin-28,synaptophysin and tyrosine dioxydase(TH)in Striatum by Western blot.In addition,slices of bilateral PD rats after DBS were stained to observe the expression of Calbindin-28 and synaptophysin in substantia nigra by Immunohistochemistry.Results High frequency stimulation impaired the rotational frequency 31% of unilateral PD rats triggered by apomophine;Long-term DBS increased the expression of TH in innocent striatum of unilateral PD rats 78.6%?9.5%,since the ipsilateral striatum(lesion side) was TH depleted by 6-OHDA insults;Calbindin-28 expression in ipsilateral striatum of hemi-PD rats raised up 75.4%?15.0% and long-term DBS reduced the effect by 43.0%?7.1%,meanwhile Calbindin-28 positive neurons in substantia nigra compacta in sham,PD and DBS rats were 74.5?10.2,75.7?15.6, 33.1?7.8.However,Synaptophysin expression in substantia nigra and striatum kept stable even after long- term DBS.Conclusions Consistent to the treatment to PD patients,DBS to STN alleviated the motor disorder of PD rats,the treatment might be based on regulating the expression of Calbindin-28 and TH.