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Neocortical High Probability Release Sites are Formed by Distinct Ca 2+ Channel to Release Sensor Topographies During Development

46 Pages Posted: 19 Mar 2019 Sneak Peek Status: Published

See all articles by Grit Bornschein

Grit Bornschein

University of Leipzig - Carl-Ludwig-Institute for Physiology

Jens Eilers

University of Leipzig - Carl-Ludwig-Institute for Physiology

Hartmut Schmidt

University of Leipzig - Carl-Ludwig-Institute for Physiology

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Abstract

Coupling distances between Ca2+ channels and release sensors regulate the vesicular release probability (pr). Tight coupling is thought to provide a framework for high pr and loose coupling for high plasticity at low pr. At synapses investigated during development, coupling distances decreased, thereby, increasing pr and transfer fidelity. We found neocortical high-fidelity synapses to deviate from these rules. Paired recordings from pyramidal neurons with ‘slow’ and ‘fast’ Ca2+ chelators combined with experimentally constrained simulations suggest that coupling tightened significantly during development. However, fluctuation analysis revealed that neither pr (~0.63) nor the number of release sites (~8) changed concomitantly, although amplitude and time-course of presynaptic Ca2+ transients were not different between age groups. These results are explained by high-pr release sites with Ca2+ microdomains in young and nanodomains in mature synapses. Thus, developmental reorganization of the active zone left pr unaffected at a neocortical synapse, emphasizing developmental and functional synaptic diversity.

Keywords: Pyramidal neurons, neocortex, quantal parameters, Ca2+ imaging, Ca2+ channel subtypes, EGTA, BAPTA, numerical simulations, coupling, microdomain, nanodomain

Suggested Citation

Bornschein, Grit and Eilers, Jens and Schmidt, Hartmut, Neocortical High Probability Release Sites are Formed by Distinct Ca 2+ Channel to Release Sensor Topographies During Development (March 16, 2019). Available at SSRN: https://ssrn.com/abstract=3353704 or http://dx.doi.org/10.2139/ssrn.3353704
This is a paper under consideration at Cell Press and has not been peer-reviewed.

Grit Bornschein

University of Leipzig - Carl-Ludwig-Institute for Physiology ( email )

Marschnerstrasse 31
D-04109 Leipzig, 04109
Germany

Jens Eilers

University of Leipzig - Carl-Ludwig-Institute for Physiology

Marschnerstrasse 31
D-04109 Leipzig, 04109
Germany

Hartmut Schmidt (Contact Author)

University of Leipzig - Carl-Ludwig-Institute for Physiology ( email )

Marschnerstrasse 31
D-04109 Leipzig, 04109
Germany

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