Regensburg 2019 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 15: Focus session: Collective Dynamics in Neural Networks
BP 15.2: Vortrag
Mittwoch, 3. April 2019, 10:00–10:15, H11
Precise Synaptic Balance in a Homolog of Olfactory Cortex — Peter Rupprecht1,2 and •Rainer Friedrich1,2 — 1Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland — 2University of Basel, Basel, Switzerland
In the classical balanced state, uncorrelated excitatory and inhibitory inputs result in irregular spiking that is inefficient for specific computations. More recently, theoretical studies have shown that correlating excitatory and inhibitory inputs on a short timescale (tight balance) and in a multi-dimensional coding space (detailed balance) can neutralize these drawbacks of balanced networks.
We used whole-cell voltage-clamp recordings in the intact zebrafish brain to directly analyze synaptic inputs to neurons in a distributed olfactory memory network. We found that large excitatory and inhibitory recurrent inputs establish a transient balanced state during odor stimulation. Using 20 Hz upstream oscillations as a reference clock to align excitatory and inhibitory inputs in time, we found a tight balance, with inhibition tracking excitation by a 3 ms delay. Finally, by studying the odor-specificity of excitatory and inhibitory inputs, we found inhibition and excitation to be co-tuned, as a signature of a detailed, high-dimensional balance in stimulus space. This precise synaptic balance implies specific and non-random connectivity among neurons, despite the absence of an obvious topography in olfactory cortex. We propose that this network is the substrate for a pattern classification process that is fast, as in classical balanced networks, but also stable in many coding directions.