Beta and Low Gamma Oscillation Dynamics in Primary Motor Cortex of 6-OHDA hemi-Parkinson’s Rat during Voluntary Movement Initiation
Master of Science
The reduction in the number of dopamine (DA) cells in subthalamic nucleus (STN) is the pathological signature of the patients with Parkinson’s Disease. With the loss of DA regulation, abnormally high power of electrophysiological oscillations, from 20 to 45 Hz near beta and low gamma band, in primary motor cortex (M1) is observed and is believed to be the reason of bradykinesia in DA patients. Studies using 6-hydroxydopamine (6-OHDA) rat model showed the frequency and power modulation of the abnormal oscillation during movement. However, constrained environment, for instance, treadmill for forced movement , did not demonstrate the voluntary aspect or allow to target the transition between behavioral statuses of 6-OHDA-lesioned rats. And the temporal dynamics of the abnormal rhythm during behavior and how it is different from healthy rat’s M1 signal oscillation is still not understood. Here, we used simultaneous video tracking and electrocorticography (ECoG) recording of M1 in both hemispheres of 6-OHDA-induced hemiparkinsonian rats during free moving on customized tracks. Behavioral performance degradation of rats from early lesion stage to late lesion stage was showed with the change of defined movement initiation (MI) events. Based on the findings, we suggest that there are components in different frequency bands in the abnormal oscillation in M1 of 6-OHDA lesioned rats and they have different likelihoods to happen during the initiation of a behavior. The potential multiple types of rhythm inside M1 could help us understand the dynamics of lack of regulation of DA cells in STN.
6-OHDA, Parkinson’s Disease, primary motor cortex, beta rhythm, voluntary movement, ECoG