Cellular dynamics involved in sound localization

The early stages of binaural processing involve components that appear to be well-designed for precise temporal processing. Neurons that perform coincidence detection for low frequency inputs respond best to rapidly changing inputs. They fire in a phasic manner not tonically and they phase-lock with high vector strength (VS) up to 2 KHz or so. Several features at the biophysical level have been identified, to more or less extent, in the avian nucleus laminaris (NL) and the mammalian medial superior olive (MSO) that distinguish these neurons. They have fast ionic currents and brief time constants; they receive bilateral inputs on segregated bipolar dendrites and the excitatory synaptic currents are generally fast; they have a low-threshold potassium current that renders them phasic. This talk will review some of these features and describe recent modeling and experimental studies that provide additional insights into the nonlinear mechanisms by which enhancement to temporal processing can occur.