Tuning Low-Voltage-Activated A-Current for Silent Gain Modulation

摘要

Modulation of stimulus-response gain and stability of spontaneous (un-stimulated) firing are both important for neural computation. However, biologically plausible mechanisms that allow these distinct functional capabilities to coexist in the same neuron are poorly defined. Low-threshold, inactivating (A-type) K~+ currents (I_A) are found in many biological neurons and are historically known for enabling low-frequency firing. By performing simulations using a conductance-based model neuron, here we show that biologically plausible shifts in I_A conductance and inactivation kinetics produce dissociated effects on gain and intrinsic firing. This enables I_A to regulate gain without major changes in intrinsic firing rate. Tuning I_A properties may thus represent a previously unsuspected single-current mechanism of silent gain control in neurons.