Dendritic morphology, inward rectification, and the functional properties of neostriatal neurons
Single neuron computation
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Neural Computation
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Due to the involvement of nucleus accumbens (NAc) medium spiny neurons (MSNs) in diverse behaviors, their excitability changes can have broad functional significance. Dopamine modulates the biophysical behavior of MSNs. In ~40% of MSNs, inward rectifying potassium (K"I"R) currents inactivate significantly, imparting greater excitability. Employing a 189-compartment computational model of the MSN and using spatiotemporally distributed synaptic inputs, the regulation of excitability by K"I"R inactivation and dopaminergic modulation was investigated and quantitatively characterized. It was shown that by forming different combinations, these regulating agents could fine tune MSN excitability across a wide range. With existing evidence indicating MSNs with and without K"I"R inactivation to be the likely targets for D2- and D1-receptor mediated modulations, respectively, the present findings suggest that dopaminergic channel modulation may intensify the existing excitability difference between them by suppressing the excitability of MSNs without K"I"R inactivation while further enhancing the excitability of the more excitable MSNs with K"I"R inactivation. On the other hand, the combined modulation of channels and synapses by dopamine may reverse the relative excitability of one cell type with respect to the other.