Sign Inversion in a Large Auditory Brainstem Synapse

Auditory information processing in the brainstem relies on a high temporal precision of the underlying physiological processes. For example, natural sounds contain sharp transients, which are generally associated with a broad frequency spectrum that generates strong responses over wide range of auditory frequency channels (spectral splatter) potentially masking other important spectral information.

A particular feature of the ventral nucleus of the lateral lemniscus (VNLL) is to produce temporally precise inhibition locked to sound transients with little temporal variance for all sound intensities. Precise VNLL inhibition is thought remove spectral splatter in downstream processing centers.

Using in-vitro physiology and computational circuit modelling, our paper shows that particularly short-term synaptic depression at the large excitatory VNLL terminal underlies such sound intensity-invariant onset inhibition that is crucial for filtering out unwanted activity. 

Figure Legend:
Simulated excitatory synaptic currents at a population of VNLL neurons with varying center frequency (CF) in response to a sentence of spoken language. Top: Model variant without short-term synaptic plasticity (STP). Bottom: Model variant with STP. STP fleshes out transients over a broad range of CFs. 

Original publication:
Linda Fischer, Florian Jenzen, Michael Rebhan, Christian Leibold, and Felix Felmy (2022): Synaptic Mechanisms Underlying Temporally Precise Information Processing in the VNLL, an Auditory Brainstem Nucleus. 
In: Journal of Neuroscience 42(34), 6536-6550. 

Read more: https://www.jneurosci.org/content/42/34/6536