| The mainly lesioned location of Parkinson's disease(PD) is the substantia nigra and basal ganglia, of which the globus pallidus external segment(GPe) is an important relaying nucleus and the globus pallidus internal segment(GPi) is a main output nucleus. Aims: This research aimed to study the alterations of spikes and local field potentials(LFPs) in GPe and GPi and their correlation in PD rats. 1. This research tried to quantitatively evaluate the motor deficit sympotoms of PD rats. 2. This research tried to study the alterations of spikes and LFPs in GPe and GPi of PD rats in silent and continuous locomotor status. 3. This research tried to study the alterations of correlation between GPe and GPi in PD rats. Methods: In this study, the model of PD rat was built up. Two multichannel electrode arrays were implanted into GPe and GPi in a PD rat respectively with the stereotaxic technique, then signals of spikes and LFPs in rats under silent and continuous locomotor status were recorded simultaneously using the 16-Channel Omni Plex? Neural Data Acquisition System(Plexon, Inc., Dallas, USA). The collected spike signals were imported to Offline Sorter to do cluster-sorting analysis and then imported to Neuro Explorer to analyze the changes of the firing pattern and firing rate of each type of neuron. The collected LFP signals were imported to Matlab to analyze the LFP power spectra, the time-frequency spectrograms and the assessment of relevant LFP power. The alterations of correlation between GPe and GPi were evaluated by means of cross correlation analysis and coherence analysis using Chronux in Matlab.Results:1. The effect of PD on the behavioral tests: Compared to control rats, the longest moving time(min) of PD rats was shorter(18.00±2.74 vs 26.98±0.91, P=0.03 and 3.33±1.45 vs 26.67±0.71, P<0.01, respectively), step frequency(steps/min) was lower(73.33±7.00 vs 95.50±4.94, P=0.04 and 76.33±7.41 vs 110.33±7.58, P<0.01, respectively), the slip up times(times) were higher(7.50±0.76 vs 1.50±0.43, P<0.01 and 10.00±0.00 vs 2.00±0.58, P<0.01, respectively) under the rotation speed of 20 r/min and 30 r/min. The discontinuous moving frequency of these two groups of rats was lower under 12 r/min. Thus, the 12 r/min is used to record signals of rats in continuous locomotor status.2. The effect of PD on the spikes in GPe: According to the firing rate and firing pattern of neurons in GPe, the recorded neurons could be divided into two types, including high frequency pausers(HFP) and low frequency bursters(LFB). Compared to control rats, HFP type of neuron in PD rats showed a lower firing rate(spikes/s)(11.89±0.98 vs 18.63±1.50, P<0.01 and 16.08±1.51 vs 23.25±1.27, P<0.01, respectively) and a higher CV value(1.06±0.05 vs 0.72±0.04, P<0.01 and 1.33±0.03 vs 1.00±0.03, P<0.01, respectively), LFB type of neuron showed a lower firing rate(6.11±0.39 vs 10.33±0.79, P<0.01 and 10.18±0.51 vs 13.15±0.66, P<0.01, respectively) and a higher CV value(2.31±0.23 vs 1.54±0.08, P<0.01 and 2.48±0.21 vs 1.62±0.15, P<0.01, respectively) in silent and continuous locomotor status. Compared to silent status, HFP type of neuron of control and PD rats in continuous locomotor status had a higher firing rate(23.25±1.27 vs 18.63±1.50, P=0.03 and 16.08±1.51 vs 11.89±0.98, P=0.03, respectively) and a higer CV value(1.00±0.03 vs 0.72±0.04, P<0.01 and 1.33±0.03 vs 1.06±0.05, P<0.01, respectively), LFB type of neuron had a higher firing rate(13.15±0.66 vs 10.33±0.79, P=0.01 and 10.18±0.51 vs 6.11±0.39, P<0.01, respectively).3. The effect of PD on the spikes in GPi: There was only one GPi type of neuron. Compared to control rats, GPi type of neuron in PD rats showed a higher firing rate(27.05±1.66 vs 23.18±1.25, P<0.01 and 29.93±0.68 vs 25.16±0.65, P<0.01, respectively) and a higher CV value(1.04±0.08 vs 0.72±0.03, P<0.01 and 1.12±0.04 vs 0.89±0.03, P<0.01, respectively) in silent and continuous locomotor status. Compared to silent status, GPi type of neuron of control and PD rats in continuous locomotor status had a higher firing rate(25.16±0.65 vs 23.18±1.25, P=0.03 and 29.93±0.68 vs 27.05±1.66, P<0.01, respectively) and a higher CV value(0.89±0.03 vs 0.72±0.03, P<0.01 and 1.12±0.04 vs 1.04±0.08, P=0.03, respectively).4. The effect of PD on LFP activities in GPe and GPi: In silent status, compared to control group, the percentage power of 0.5~12 Hz of GPe and GPi in PD rats was lower(59.27±3.28 vs 74.44±1.68, P<0.01 and 67.99±1.60 vs 80.88±1.80, P<0.01, respectively) and the percentage power of 12~35 Hz was higher(28.32±1.94 vs 18.74±1.54, P<0.01 and 26.32±2.16 vs 11.45±1.07, P<0.01, respectively). In continuous locomotor status, compared to control group, the percentage power of 0.5~12 Hz of GPe and GPi in PD rats was lower(66.76±1.83 vs 79.11±2.80, P<0.01 and 62.69±1.79 vs 76.79±1.19, P<0.01, respectively) and the percentage power of 12~35 Hz was higher(24.53±1.64 vs 13.65±1.91, P<0.01 and 27.15±1.51 vs 16.10±0.80, P<0.01, respectively) and the percentage power of 35~70 Hz was higher(3.03±0.48 vs 1.07±0.46, P=0.04 and 4.77±0.65 vs 2.03±0.34, P<0.01, respectively).5. The effect of PD on correlation between GPe and GPi: Compared to control group, the correlation coefficients between GPe and GPi in PD rats was much higher in frequency bands of 0.5~12 Hz and 12~35 Hz(0.81±0.02 vs 0.37±0.03, P<0.01 and 0.81±0.03 vs 0.43±0.07, P<0.01, respectively) and the average phase coherence value was also higher(0.69±0.03 vs 0.25±0.01, P<0.01 and 0.73±0.04 vs 0.30±0.06, P<0.01, respectively).Conclusions: the behavioral tests showed that, PD rats had motor deficit sympotoms and disability of movement control and movement coordination in high rotation speed. 12 r/min was an appropriate rotation speed to record moving signals. The results of spikes and LFPs in GPe and GPi suggested that these two nuclei were related to PD and locomotion. The correlation between the synchronously recorded signals of GPe and GPi increased. |
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