Inhibitory-excitatory synaptic timing determines a midbrain neuron’s best modulation frequency.

Evidence

The band-enhanced model (Fig. 1 , BE) was Nelson and Carney’s ( 2004 ) same-frequency inhibitory-excitatory (SFIE) model. The key mechanism in this model is a dynamic interaction between relatively short-duration excitatory and relatively long-duration, delayed inhibitory synaptic potentials. The durations of the excitatory and inhibitory potentials and the delay of the inhibition with respect to the excitation determine the model’s best modulation frequency (BMF). An extension of the SFIE model was used for the band-suppressed model (Fig. 1 , BS). This model receives the same ascending excitatory input as the band-enhanced model, but it is inhibited by the band-enhanced model (Carney et al. 2015 ; Kim et al. 2015b ). The BMF of the band-enhanced model determines the worst modulation frequency (WMF) for the band-suppressed model. Finally, the hybrid MTF model receives the same ascending excitatory input as the other model IC neurons, but is inhibited by both band-enhanced and band-suppressed cells (Fig. 1 , Hybr). The relation between the BMF and WMF of the inhibitory inputs determines the shape of the hybrid model cell’s MTF. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5478

Categorization

• DEFINE: Clarifies how the SFIE model and the three MTF types (band-enhanced, band-suppressed, hybrid) are mechanistically derived from excitatory/inhibitory synaptic timing.
• XREF: The competitive excitatory-vs-delayed-inhibitory timing explanation parallels neural feature-tuning logic seen in many lateral-inhibition circuits (e.g., visual cortex orientation selectivity).