Optogenetic investigation of cortical inhibitory interneurons
In order to approach mechanisms underlying adaptive auditory coding in mammals, we need to be able to manipulate larger populations of neurons in intact animals. Optogenetics provide a toolbox to precisely manipulate well-defined populations of neurons in awake-behaving animals. Currently, we are focusing on the functional role of different classes of inhibitory neurons in rodent primary auditory cortex (ACx). We established an experimental set-up for awake, freely moving mice where we can record from populations of single units in ACx while manipulating different classes of inhibitory cells optogentically.
In order to better understand how the manipulation of inhibitory networks changes cortical dynamics we are developing computational models in collaboration with Maneesh Sahani and Jennifer Linden at UCL London.
Development of an optogenetic auditory mid-brain implant
Optogenetics offer a completely new way of delivering information directly to the brain. This is specifically interesting for neural prostheses. Patients with auditory nerve damage need auditory implants at more central stations in order to restore their hearing. We explore new optic fibre types and stimulation strategies for auditory mid-brain implants. This work is done in collaboration with the biophotonics group of Alexander Heisterkamp and the neuroprostheses laboratory of Andrej Kral at the MH Hannover.
Behavioral assessment of altered inhibition in the auditory cortex
In order fully understand the role of altered inhibition in sensory processing and for adaptive control of the auditory system we need to be able to observe auditory processing at the perceptual level. We have developed a behavioral paradigm that enables us to test mice in a perceptual task while we are performing neural recordings and optogenetic manipulations at the same time.
Age-related changes of central auditory processing stages
Age-related hearing loss can partly be attributed to peripheral degeneration, but some perceptual deficits have been linked to changes of more central processing stages. Specifically, altered inhibition in the auditory cortex has been proposed to cause age-related auditory processing disorders. However, whether theses changes are a direct consequence of altered peripheral input or develop independently is currently not known. We are characterizing two lines of mice that differ only in the mutation at a single locus, causing one of the lines to develop age-related hearing loss. We measure auditory brainstem responses in young and aged animals and perform histology to quantify changes in inhibitory cell populations. We also test these animals in behavioural tasks.