A possible functional organization of the corticostriatal input within the weakly-correlated striatal activity: a modeling study.

Recently, it was reported in an in vivo study that pairs of the striatal projection neurons (medium-sized spiny neurons) of the basal ganglia show asynchronous spiking within weakly-correlated subthreshold depolarized states. In this computational study, we investigate a possible functional organization of corticostriatal inputs that accounts for the experimental observations within known anatomical and physiological constraints. In a pair of medium-sized spiny neurons, a small fraction of corticostriatal fibers is common to both neurons. To explain the weak correlations in sub- and supra-threshold activities of the neuron pair, we postulate that the two input channels, common or specific to the individual neurons, have distinct functional roles. The common input channel delivers random spike trains and is primarily responsible for the initiation and maintenance of the depolarized states. In contrast, the input through the neuron-specific channels elicit postsynaptic spikes by delivering intermittently-synchronized spikes. The results of this model were compared with those derived from a newly-performed analysis of the previous double-intracellular recording data. We show that the behavior of this model agrees qualitatively and quantitatively with that of the medium-sized spiny neurons observed in the experiments in a certain range of the coincident time window.