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Front. Neuroanat. | doi: 10.3389/fnana.2018.00012

Topographic organization of hippocampal inputs to the anterior olfactory nucleus

  • 1Department of Cell and Systems Biology, University of Toronto, Canada
  • 2Department of Psychology, University of Toronto, Canada

Top-down processes conveying contextual information play a major role in shaping odour representations within the olfactory system, yet the underlying mechanisms are poorly understood. The hippocampus (HPC) is a major source of olfactory top-down modulation, providing direct excitatory inputs to the anterior olfactory nucleus (AON). However, HPC-AON projections remain uncharacterized. In an effort to understand how hippocampal inputs are distributed within the AON, we systematically outlined their organization using anterograde and retrograde tracing methods. We found that AON-projecting hippocampal pyramidal neurons are located mostly in the ventral two-thirds of the HPC and are organized topographically such that cells with a ventral to intermediate hippocampal point of origin terminate, respectively, at the medial to lateral AON. Our neuroanatomical findings suggest a potential role for the hippocampus in the early processing and contextualization of odours which merits further investigation.

Keywords: AON, tracing, topography, Hippocampus, Olfaction, anterograde, retrograde, CA1

Received: 22 May 2017; Accepted: 07 Feb 2018.

Edited by:

Ricardo Insausti, Universidad de Castilla-La Mancha, Spain

Reviewed by:

Joachim H. Lübke, Forschungszentrum Jülich, Germany
Aldis P. Weible, University of Oregon, United States  

Copyright: © 2018 Aqrabawi and Kim. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Jun Chul Kim, University of Toronto, Department of Psychology, 100 St. George Street, Toronto, M5S 3G3, Ontario, Canada, kim@psych.utoronto.ca