Mehnoush Faghani: Characterization and modeling of extracellular field potentials generated by inhibitory synaptic currents in the nucleus laminaris of barn owl

BCCN Berlin / Technische Universität Berlin

Abstract

 

The nucleus laminaris (NL) is the first binaural nucleus in the auditory brain stem circuit of barn owls. This nucleus is responsible for interaural time differences computation to localize the sound source azimuth. In this processing, inhibition plays a key role in gain control and regulating the detecting neurons’ working range regardless of the acoustic signal intensity. However, it is still unknown how much inhibitory current is involved in this circuit, and what kind of dynamics these currents exhibit. I hypothesize that in NL the extracellular field potentials have contributions from GABAergic and glycinergic synaptic currents. Here I thus study the effect of inhibitory currents on the creation of extracellular field potentials in the NL of barn owls in vivo. I analyze experimentally recorded extracellular potentials generated by these two types of inhibition, separately and together. I model the inhibitory currents by using short-term depression, as well as short-term plasticity including both facilitation and depression. I quantify the goodness of the fit obtained by the different models by using Akaike’s information theoretic criterion (AIC) and its corresponding weight. The quantification of the results shows that both GABAergic and glycinergic currents make a significant contribution to the field potential. Furthermore, the short-term plasticity model including both depression and facilitation is the best model to quantify the majority of extracellular field potentials generated by inhibitory synaptic currents. The data also suggest that the simultaneous contribution of GABAergic and glycinergic synaptic currents to the extracellular field potentials is sublinear with respect to the separate contributions of these currents.

 

Additional Information

Master Thesis Defense

 

Organized by

Prof. Dr. Richard Kempter   & Dr. Paula Kuokkanen   / Lisa Velenosi