PD Dr. Thomas Künzel

Position:
Scientist, subgroup “Auditory Neurophysiology”

Started in:
Institute for Biology 2: January 2011; Department of Chemosensation: September 2018

Fields of Research:
Physiology of sound-processing in the auditory brainstem

Methods:
In-vivo electrophysiology, in-vitro electrophysiology, biophysical simulation of neuronal processing, neuroanatomy

Contact:
kuenzel@bio2.rwth-aachen.de
Phone: +49 (0)241 / 80-24854
ORCID: 0000-0003-0993-8524

Research projects:

Descending cholinergic connections in the auditory pathway
Synaptic connections converge on neurons of the anteroventral cochlear nucleus of the Mongolian gerbil (green: Calretinin; red: SV2).

Descending and lateral connections in sensory brain pathways likely play an important role during information processing in a complex, dynamic and unpredictable sensory world. Compared to the principle processing functions of sensory pathways, our knowledge about mechanisms and functions of descending projections in sensory processing is quite limited.
An example of such a system is the descending cholinergic connection into the auditory brainstem, which we examine in this project.
For this we use in vitro electrophysiology, computer simulations of neuronal processing, and neuroanatomical methods to analyze the cellular mechanisms and the anatomy of the cholinergic connections.
We also use in vivo electrophysiology (auditory brainstem responses, electrocochleography, loose-patch single-unit recordings) under sound stimulation to better understand the role of the cholinergic connections in hearing.

Synaptic physiology of time-coding neurons
Spherical bushy cells in the anteroventral cochlear nucleus of Mongolian gerbils, filled with biocytin during whole-cell recording in acute brain slices.

Auditory nerve axons carry sound information from the inner ear to the brain. They form very large axosomatic synapses, the so-called endbulbs of Held with certain neurons of the cochlear nucleus.
We examine the function and the development of these auditory giant synaptic terminals by using in vitro electrophysiology in acute brain slices of mice and Mongolian gerbils.

Modeling of input interactions in time-coding neurons
Auditory nerve fibers in the Mongolian gerbil revealed by immunocytochemical staining against the protein Calretinin.

Time-coding neurons in the anteroventral cochlear nucleus receive powerful excitatory axosomatic inputs via the endbulbs of Held of the auditory nerve. However, there are also small and weak auditory nerve contacts in the dendritic tree of these cells. The function and role in hearing of the small dendritic inputs is unknown and their interaction with the giant axosomatic input is not understood.
We therefore try to better understand this synaptic system with the aid of biophysical models and simulated experiments. For this, we mainly use NEURON [https://neuron.yale.edu/neuron/].

Physiological basis of adaptive processing in the inferior colliculus
Neuron in the core of the central nucleus of the inferior colliculus of the chicken, filled with biocytin during whole-cell recording in acute brain slices.

Inferior colliculus is an obligatory station of the auditory pathway. All auditory information must pass through this complex brain area. Information that was processed in parallel converges here and complex processing steps take place. These manifest for example in adaptive responses to repeated sound stimulation. However, the circuits and physiological properties of neurons in the inferior colliculus are surprisingly poorly understood.
We thus work on characterizing the biophysical and synaptic properties of neurons in various parts of the inferior colliculus of the chicken to better understand the “building blocks” of complex processing.

Publications:

External cooperations:

Current group members:

  • Charlene Gillet – PhD student
  • Hannah-Lena Tröger – Animal keeping

Former group members:

  • Jule Buchholz (BSc thesis)
  • Luisa Fensky (BSc thesis)
  • Peter Kaleta (BSc thesis)
  • Anna Hilverling (MSc thesis)
  • Richard Sinzig (MSc thesis)
  • David Goyer (PhD thesis)
  • Sebastian Malinowski (BSc thesis)
  • Hannah Griebel (MSc thesis)
  • Jana Wolf (BSc thesis)
  • Sven Kuspiel (BSc thesis)
  • Kerstin Doerenkamp (MSc thesis)
  • Maike Schaper (MSc thesis)
  • Elisabeth Koert (BSc thesis)
  • Severin Graff (BSc thesis)
  • Elena Müller-Limberger (animal keeping)

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