Year: 2016
Type: article
Abstract: UNLABELLED: Although feedback or centrifugal projections from higher processing centers of the brain to peripheral regions have long been known to play essential functional roles, the anatomical organization of these connections remains largely unknown. Using a virus-based retrograde labeling strategy and 3D whole-brain reconstruction methods, we mapped the spatial organization of centrifugal projections from two olfactory cortical areas, the anterior olfactory nucleus (AON) and the piriform cortex, to the granule cell layer of the main olfactory bulb in the mouse. Both regions are major recipients of information from the bulb and are the largest sources of feedback to the bulb, collectively constituting circuits essential for olfactory coding and olfactory behavior. We found that, although ipsilateral inputs from the AON were uniformly distributed, feedback from the contralateral AON had a strong ventral bias. In addition, we observed that centrifugally projecting neurons were spatially clustered in the piriform cortex, in contrast to the distributed feedforward axonal inputs that these cells receive from the principal neurons of the bulb. Therefore, information carried from the bulb to higher processing structures by anatomically stereotypic projections is likely relayed back to the bulb by organizationally distinct feedback projections that may reflect different coding strategies and therefore different functional roles. SIGNIFICANCE STATEMENT: Principles of anatomical organization, sometimes instantiated as "maps" in the mammalian brain, have provided key insights into the structure and function of circuits in sensory systems. Generally, these characterizations focus on projections from early sensory processing areas to higher processing structures despite considerable evidence that feedback or centrifugal projections often constitute major conduits of information flow. Our results identify structure in the organization of centrifugal feedback projections to the olfactory bulb that is fundamentally different from the organization of feedforward circuits. Our study suggests that understanding computations performed in the olfactory bulb, and more generally in the olfactory system, requires understanding interactions between feedforward and feedback "maps" both structurally and functionally.
Source: Journal of Neuroscience
Authors: K. Padmanabhan, F. Osakada, A. Tarabrina, E. Kizer, E. M. Callaway, F. H. Gage, T. J. Sejnowski
Language: English
Subfield: Sensory Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: hybrid
Funders: Howard Hughes Medical Institute, Pioneer Fund, Leona M. and Harry B. Helmsley Charitable Trust, Naito Foundation, Takeda Science Foundation, JPB Foundation, Uehara Memorial Foundation, National Alliance for Research on Schizophrenia and Depression, G. Harold and Leila Y. Mathers Foundation, Kanae Foundation for the Promotion of Medical Science, National Institutes of Health, Japan Society for the Promotion of Science, Office of Naval Research, National Institute of Mental Health
Awards: ENGRAFTING HUMAN NEURONS INTO ANIMAL MODELS TO STUDY SCHIZOPHRENIA, G138538273, Connectivity and Function of Inhibitory Cortical Neurons, Engrafting human neurons into animal models to study schizophrenia, G4524317848, in vivo imaging of transplanted human induced-Pluripotent Stem Cell (iPSC) derived neurons to model neurological and psychiatric disorders
OpenAlex ID: W2474800249