Are Rigidity and Tremor Two Sides of the Same Coin in Parkinson's Disease?

In this research, we evaluate the inter-relation of tremor and rigidity in order to find whether they are the two sides of the same coin in Parkinson's disease (PD). We include the agonist and antagonist skeletal muscle models as well as the peripheral (spinal and long loop reflexes) and central (basal ganglia and cortex) mechanisms and try to present a complete model of PD. All of our simulation is developed in SIMULINK, MATLAB 7. For simulating the muscle dynamics, we used the mechanical model of Hill. Input of the model is from CNS and the output is angular movement. The agonist and antagonist muscles are used simultaneously to simulate the tremor and its relation to the rigidity. Our abstract model of Basal ganglia is able to simulate the physiological tremor. Voluntary co-contraction of muscles increases the tremor, which is physiologically plausible. The model is also able to produce The PD rest tremor. Our results showed that increased supplementary motor area output increases the rigidity. Finally our model indicated that Rigidity worsens the tremor and vice versa. We suggest that the treatment of these two abnormal motor behaviors must be fulfilled simultaneously. It seems that curing one of these two symptoms without decreasing the other is not realistic. It is worth noting that experimental studies are needed to validate this computational model.

کلیدواژه ها:

Parkinson's disease ، Tremor ، Rigidity ، Mathematical model ، Long loop reflex.