Computationally going where experiments cannot: a dynamical assessment of dendritic ion channel currents during -like states.

Despite technological advances, how specific cell types are involved in brain function remains shrouded in mystery. Further, little is known about the contribution of different ion channel currents to cell excitability across different neuronal subtypes and their dendritic compartments . The picture that we do have is largely based on somatic recordings performed . Uncovering ion channel current contributions in neuron subtypes that represent a minority of the neuronal population is not currently a feasible task using purely experimental means. We employ two morphologically-detailed multi-compartment models of a specific type of inhibitory interneuron, the oriens lacunosum moleculare (OLM) cell. The OLM cell is a well-studied cell type in CA1 hippocampus that is important in gating sensory and contextual information. We create -like states for these cellular models by including levels of synaptic bombardment that would occur . Using visualization tools and analyses we assess the ion channel current contribution profile across the different somatic and dendritic compartments of the models. We identify changes in dendritic excitability, ion channel current contributions and co-activation patterns between and -like states. Primarily, we find that the relative timing between ion channel currents are mostly invariant between states, but exhibit changes in magnitudes and decreased propagation across dendritic compartments. We also find enhanced dendritic hyperpolarization-activated cyclic nucleotide-gated channel (h-channel) activation during -like states, which suggests that dendritically located h-channels are functionally important in altering signal propagation in the behaving animal. Overall, we have demonstrated, using computational modelling, the dynamical changes that can occur to ion channel mechanisms governing neuronal spiking. Simultaneous access to dendritic compartments during simulated states shows that the magnitudes of some ion channel current contributions are differentially altered during -like states relative to .