Research About The Change Of The Firing Characteristic Of STN And M1 And Their Relationship In Rat Of Parkinson’s Disease

In this research, we used 6-hydroxydopamine(6-OHDA) to establish rat model of Parkinson’s disease(PD). Using multi-channel recording technique, the spike activities and the local field potentials(LFPs) in subthalamic nucleus(STN) and primary motor cortex(M1) were recorded simultaneously in rats under a sober state of rest and a specific locomotor state. The alterations of electrophysiological characteristics in STN and M1 and their relationships were analyzed in control and PD rats with Offline Sorter, Neuro Explorer and Matlab.Aims: This research aims to offer a theoretical basis for seeking faster and more efficient therapy methods and exploring the mechanisms in the pathophysiology of PD.Results: According to the firing pattern and firing rate of single neuron, the neurons of STN were classified into 2 types. In rest state, compared to control rats(2.97±0.20), the firing rate(Hz)of second type of neurons in PD rats(4.30±0.87) increased significantly, and the coefficient of variation of second type neuron in PD rats(1.06±0.04) increased significantly compared to control group(0.95±0.01). And in specific limb movement condition, compared to control rats(14.07±1.16), the firing rate(Hz) of second type of neurons in PD rats(18.64±0.35) also increased significantly. However, the first type of neurons in STN had no significant difference between control and PD group. Under the state of rest, the local field potentials in STN of PD rats at each frequency band all changed significantly from control group: the relative power of0.7~12 Hz in 0.7~200 Hz in PD rats(70.66±0.73) declined significantly compared to control group(80.75±2.35) and relative power of other bands increased greatly. Under locomotor state,the relative power of 0.7~12 Hz frequency-band in PD rats(65.27±1.48) also declined significantly compared to control group(73.85±1.73), but in 12~35 Hz frequency-band, PD rats had a significantly increased(21.92±0.80) relative power compared to control group(13.95±1.56).The relative power of other bands had no obvious changes.The neurons of M1 were classified into 2 types as well: inter neuron and pyramidal neuron.Under rest state, compared to control group(4.23±0.70), the firing rate(Hz) of pyramidal neurons of PD rats(3.11±0.47) declined significantly, and the coefficient of variation of pyramidal neuron in PD rats(0.92±0.03) declined significantly compared to control group(0.97±0.03).However, no significant changes were observed in the analysis of the electrophysiological activities of interneurons. Under locomotor state, the firing rate(Hz) of interneurons(17.36±1.59) and pyramidal neurons(11.55±0.39) in experimental group both decreased greatly compared to the interneurons(28.49±1.18) and pyramidal neurons(16.70±1.00)in control group. Under the state of rest, the relative power of 0.7~12 Hz in 0.7~200 Hz in PD rats(41.14±1.30) declined significantly compared to control group(49.15±2.40), but in 12~35Hz frequency-band, PD rats(28.85±2.23) increased significantly compared to control rats(17.66±0.51). The power percentage of other bands had no obvious changes.Through the correlation analysis of local field potentials recorded synchronously in STN and M1, we could concluded that the correlation coefficient in 0.7 ~ 12 Hz of PD rats(0.52±0.02)increased significantly compared to control group(0.44±0.02) and in 12~35 Hz frequency–band, PD rats(0.49±0.01)had an significantly increased relative power compared to control group(0.40±0.01). The mean phase coherence had similar result to correlation coefficient above: the mean phase coherence in 0.7~12 Hz band(0.59±0.02) and 12~35 Hz band(0.51±0.03)of PD rats both increased greatly compared to control group in 0.7~12 Hz band(0.52±0.02) and12~35 Hz band(0.41±0.02).Conclusions: In summary, we report specific alterations of spikes and LFPs activities in STN and M1 and the alterations of their correlationship after dopamine loss in both resting and locomotor state, from which we can assume there are important fiber connections between these two nuclei and it gives us the theoretical foundation for the treatment of Parkinson’s disease.