The influence of descending cholinergic connections on information processing in the initial stages of the central auditory pathway
Final Report Abstract
Neuromodulation changes neuronal information processing dependent on attention, behavior or salience of inputs and was best described for cortical circuits. However, also sensory pathways in the brainstem, usually understood to be highly specialized but functionally rigid, are subject to descending and recurring modulatory connections and the mechanism and implications of these top-down circuits are not well understood. This project aimed to understand the mechanisms behind cholinergic modulatory inputs to a type of neuron in the auditory brainstem which is highly specialized to encode the temporal information of narrow-band sound stimuli. Two different approaches were used. First the responses of this neuron type to stimulus conditions that do not activate the modulatory connection were compared to responses to stimuli that included the activation of modulatory connections. These recordings were performed in anesthetized mongolian gerbils. Our results suggest that, although the neurons now had a slightly higher response thresholds, the responses close to threshold were now more precise. In a second approach we created a computer model of the neuron type that included a realistic representation of the dendritic tree, where small, secondary inputs are located. In the model we could explore how the powerful excitation from the auditory nerve, that impinges on this neuron type, can interact with the small extra inputs. We show that the increased excitation improves the sound processing of these neurons in the model. These theoretical findings could potentially be useful to understand the experimental results of the project as well.
Publications
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Modulatory influences on time-coding neurons in the ventral cochlear nucleus. Hearing Research, 384, 107824.
Kuenzel, Thomas
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Muscarinic modulation of M and h currents in gerbil spherical bushy cells. PLOS ONE, 15(1), e0226954.
Gillet, Charlène; Kurth, Stefanie & Kuenzel, Thomas
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Small dendritic synapses enhance temporal coding in a model of cochlear nucleus bushy cells. Journal of Neurophysiology, 125(3), 915-937.
Koert, Elisabeth & Kuenzel, Thomas
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Release your inhibitions: how synaptic dynamics shape efferent activity in the auditory system. The Journal of Physiology, 600(11), 2543-2544.
Kuenzel, Thomas
