Sensitivity to extracellular potassium underlies type-intrinsic differences in retinal ganglion cell excitability

• DOI: 10.3389/fncel.2022.966425
• Publication Date: 2022-08-05T22:08:55Z
• Authors: Andrew M. Boal; Nolan R. McGrady; Michael L. Risner; David J. Calkins
• Keywords: Hyperpolarization

Neuronal type-specific physiologic heterogeneity can be driven by both extrinsic and intrinsic mechanisms. In retinal ganglion cells (RGCs), which carry visual information from the retina to central targets, evidence suggests properties shaping action potential (AP) generation significantly impact responses of RGCs stimuli. Here, we explored how differences in excitability further distinguish two RCG types with distinct presynaptic circuits, alpha ON-sustained (αON-S) OFF-sustained (αOFF-S) cells. We found that αOFF-S are more excitable modest depolarizing currents than αON-S but plateaued earlier as depolarization increased (i.e., block). addition block sensitivity, cell also produced AP shapes increasing stimulation. width variability magnitude, correlated onset block, while remained stable. then tested if observed were due sensitivity extracellular potassium. sensitive potassium concentration, shifted RGC under baseline conditions. Finally, investigated influence axon initial segment (AIS) dimensions on spiking. relationship between AIS length evoked spike rate varied not only type, strength stimulation, suggesting structure alone cannot fully explain excitability. Thus, contributes excitability, a key factor encode information.