糖心TV

The basal ganglia (BG), a collection of fore- and mid-brain nuclei, have long been implicated in both motor function and dysfunction. It has been proposed that the BG form a centralized action selection circuit, resolving conflict between multiple neural systems competing for access to the final common motor pathway formed by the brainstem and spinal cord. We present a new spiking neuron model of the BG circuitry to test this proposal, incorporating all major features and many physiologically plausible details. Novel features of this model include effects of dopamine in the subthalamic nucleus (STN) and globus pallidus (GP), transmission delays between neurons, and specific distributions of synaptic inputs over dendrites. All main parameters were derived from experimental studies. Such a complex yet constrained model allowed us to simultaneously study the proposed computational function of this brain region and validate the model by replicating multiple experimental data-sets on the firing properties of neurons in the BG. We found that the BG circuitry supports motor program selection and switching, which deteriorates with both depleted and excess dopamine in a manner consistent with pathologies associated with those states (e.g. respectively Parkinson’s Disease and amphetamine addiction). We also validated the model against data describing oscillatory properties of BG. We found that the same model displayed detailed features of both gamma-band (30-80 Hz) and slow (< 1 Hz) oscillatory phenomena reported by Brown et al. (2002) and Magill et al. (2001), respectively. Only the parameters required to mimic experimental conditions (e.g. anaesthetic) or manipulations (e.g. lesions) were changed. The results thus demonstrate that our model simultaneously captures the proposed global functional role – action selection – of this brain region and the detailed firing properties of its neurons.