Project Details
Projekt
Learning-related topographic network activity patterns of auditory corticofugal neurons
Applicant
Professor Dr. Jan Jasper Hirtz
Subject Area
Experimental and Theoretical Network Neuroscience
Cognitive, Systems and Behavioural Neurobiology
Cognitive, Systems and Behavioural Neurobiology
Term
since 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 520140856
Auditory corticofugal projections arise from deep layers of the auditory cortex (AC) and modulate the activity of upstream midbrain and brainstem targets. Past studies as well as our own preliminary data indicate that layer 5 (L5) corticocollicular (CC) neurons feature low sound selectivity and a high degree of local tuning heterogeneity, suggesting weak tonotopic organization compared to other L5 neuron types. However, these data were obtained under passive listening conditions, and thus do not take in account that context-specific activity patterns might feature a far more ordered structure, demonstrating the adaptation of AC networks. We plan to address this question using a combination of operant conditioning and two-photon Ca2+ imaging. Mice will be trained to distinguish between two pure tones, using water reward for motivation, while the activity of L5 CC neurons will be monitored simultaneously over several days. We expect learning-related adaptation of network activity expressed by decorrelation towards target and foil sounds. Furthermore, the initially weak tonotopic organization is hypothesized to sharpen, demonstrating that L5 CC neurons process frequency-related information in a topographic manner in case it is context-relevant. For comparison, we will perform the same experiment for intratelencephalic (IT) L5 AC neurons, which, according to our data, should feature a more tonotopic order even under passive listening conditions. While learning-related changes will most likely be present as well, we expect them to be less pronounced, demonstrating a comparatively high degree of plasticity of CC neurons, enabling them to strongly adapt to behaviorally relevant tasks. Most experiment will be performed in the primary AC subfield, but in addition we will repeat them for CC neurons in the secondary field as well. Interestingly, here CC neurons might according to our data actually display a more ordered topography than IT neurons in the passive listening condition. We thus expect network activity modulation to differ between AC subfields, which would provide new insight into their specific roles in auditory-related learning. Lastly, we will optogenetically disrupt the synaptic transmission of CC neurons onto neurons in the inferior colliculus. This experiment will test whether the topographic network activity modulations as well as learning itself depend on the cortico-subcortical loop. The data obtained in the proposed project would add to the understanding of the function of auditory corticofugal neurons in learning and help to further decipher the topographic arrangement of the AC across all layers and subfields.
DFG Programme
Priority Programmes
