Computational Neuroscience Group, Department of Biophysics

We are interested in the possible neural substrates of the high fidelity information transmission in sensory pathways. In particular, we ask questions about the interaction between various active conductances and plastic synaptic transmission at single neuron level.

Some of our modeling studies were motivated by the auditory brainstem nucleus, lateral superior olive (LSO):

We examined the possible functional roles of two hyperpolarization-activated conductances in lateral superior olive (LSO) principal neurons. Inputs of these LSO neurons are transformed into an output, which provides a firing-rate code for a certain interaural sound intensity difference (IID) range. Recent experimental studies have found pharmacological evidence for the presence of both the h conductance as well as the inwardly rectifying outward KIR conductance in the LSO. We addressed the question of how these conductances influence the dynamic range (IID versus firing rate). We used computer simulations of both a point-neuron model and a two-compartmental model to investigate this issue, and to determine the role of these conductances in setting the dynamic range of these neurons. The width of the dynamic regime, the frequency-current (f-I) function, first-spike latency, subthreshold oscillations and the interplay between the two hyperpolarization activated conductances are discussed in detail. The in vivo non-monotonic IID-firing rate function in a subpopulation of LSO neurons is in good correspondence with our simulation predictions. Two-compartmental model simulation results suggest segregation of h and KIR conductances on differentcompartments, as this spatial configuration could explain certain experimental results.

Here are some of our related publications to this project:

• Szalisznyó K.: Role of Hyperpolarization-activated Conductances in the Lateral Superior Olive: A Modeling Study; Journal of Computational Neuroscience (2006), 20(2):137-52.
• Szalisznyó K, Zalányi L: Role of hyperpolarization-activated conductances in the auditory brainstem; Neurocomputing 58-60 (2004) 401-407

Other works considered the effects of short term synaptic plasticity in sensory afferent pathways.
Afferent pathway of the electrosensory system in the weakly electric fish was used as biological motivation in some of these works. Related publications:

• Szalisznyó K. Longtin A, Maler L: Effect of synaptic dynamics on sensory coding and steady-state filtering properties in the electric sense, (in press, Biosystems).
• Szalisznyó K, Longtin, A and Maler, L: Altered sensory filtering and coding properties by synaptic dynamics in the electric sense; Neurocomputing 69 (2006) 1070-1075.
• Szalisznyó K, Tóth J: Temporal order of synaptic filters: Implications for F->D or D->F processes (presented at the CNS-2006 meeting)
• Zalányi L, Bazsó F, Érdi P: The effect of synaptic depression on stochastic resonance;Neurocomputing 38-40 (2001) 459-465
• Bazsó F, Zalányi L, Csárdi G: Channel Noise in Hodgkin-Huxley Model Neurons. Physics Letters A, 311/1 (2003) 13-20

Currently László Zalányi and Krisztina Szalisznyó are working on these projects.