Plasticity of olfactory bulb inputs mediated by dendritic NMDA-spikes in rodent piriform cortex

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Abstract

The piriform cortex (PCx) is essential for learning of odor information. The current view postulates odor learning in the PCx is mainly due to plasticity in intracortical (IC) synapses, while odor information from the olfactory bulb carried via the lateral olfactory tract (LOT) is 'hardwired'. Here we revisit this notion by studying location and pathway dependent plasticity rules. We find that in contrast to the prevailing view, synaptic and optogenetically activated LOT synapses undergo strong and robust long-term potentiation (LTP) mediated by only few local NMDA-spikes delivered at theta frequency, while global spike timing dependent plasticity protocols (STDP) failed to induce LTP in these distal synapses. In contrast, IC synapses in apical and basal dendrites undergo plasticity with both NMDA-spikes and STDP protocols but to a smaller extent compared with LOT synapses. These results are consistent with a self-potentiating mechanism of odor information via NMDA-spikes which can form branch-specific memory traces of odors that can further associate with contextual IC information via STDP mechanisms to provide cognitive and emotional value to odors.

Data availability

The data generated or analysed during this study are included in the manuscript and Supporting files for Figure 1C-G, Figure 2B,D, Figure 3B,D, F-H, Figure 4 B,D, Figure 5B-D, Figure 6 C-D and Figure 7 B-F, are loaded.

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Author details

Amit Kumar

Department of Physiology, Technion-Israel Institute of Technology, Haifa, Israel

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-0674-3641
Edi Barkai

Department of Neurobiology, University of Haifa, Haifa, Israel

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-7325-4269
Jackie Schiller

Department of Physiology, Technion-Israel Institute of Technology, Haifa, Israel

For correspondence
jackie@technion.ac.il

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-9182-7166

Funding

Israel Science Foundation

Jackie Schiller

Prince Center for Neurodegenerative Diseases

Jackie Schiller

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

Katalin Toth, University of Ottawa, Canada

Ethics

Animal experimentation: All animal procedures were done in accordance with guidelines established by NIH on the care and use of animals in research and were confirmed by the Technion Institutional Animal Care and Use Committee (Permit number IL-012-01-18).

Version history

Received: May 14, 2021
Preprint posted: May 25, 2021 (view preprint)
Accepted: October 25, 2021
Accepted Manuscript published: October 26, 2021 (version 1)
Version of Record published: November 8, 2021 (version 2)

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.