Figure 2.

Different structural and functional loops of the proposed multiscale cortico-basal ganglia model. (A) Outer loop, sensory-motor loop; (B) Inner loop, cortico-basal ganglia loop; (C) Central loop, nigrostriatal loop. SNc, substantia nigra pars compacta; GPe, globus pallidus externa; GPi, globus pallidus interna; STN, subthalamic nucleus; STR, striatum; Thal, thalamus; MC, motor cortex; MN, motor neuron; PC, proprioceptive cortex; PFC, the prefrontal cortex. X^targ, the target position; X^arm, the current arm position; ϕ^MN, the motor neuron activations; M_L, muscle lengths; I_gaba, inhibitory GABAergic current; DA_e, extracellular dopamine; G(t), the MC output; G(t + 1), the BG-derived activity of thalamus; V_SNc, the voltage membrane of SNc neuron; J_m,Ca, the calcium flux of SNc neuron as a function of V_SNc; J_synt, the dopamine synthesis flux as a function of calcium; P_rel, the probability release of dopamine extracellularly as a function of calcium.