Does striatum support competitive dynamics? A test of this hypothesis using a biologically realistic model of the striatal microcircuit

The striatum is the man input structure of the basal ganglia and consists principally of medium spiny neurons (MSNs). The remaining neurons comprise several species of interneuron, including the GABAergic fast spiking interneuron (FSIs). Both neuron species are highly interconnected (including a network of gap junctions between the FSIs) and both are modulated by dopamine. Understanding this complex microcircuit is therefore very challenging. Previous computational hypotheses have suggested that the inhibitory collaterals between MSNs lead to a strong competitive dynamic [1]. In contrast, Koós and Tepper [2] suggest that feed-forward inhibition from the FSIs is the dominant force in the control of MSNs. We have developed a detailed, biologically constrained model of the striatal microcircuit aimed at resolving these issues and discovering the computations performed in this critical brain area.