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Comprehensive connectivity of the mouse main olfactory bulb: analysis and online digital atlas.

Hintiryan H, Gou L, Zingg B, Yamashita S, Lyden HM, Song MY, Grewal AK, Zhang X, Toga AW, Dong HW - Front Neuroanat (2012)

Bottom Line: To facilitate use of the data, raw images are made publicly accessible through our online interactive visualization tool, the iConnectome, where users can view and annotate the high-resolution, multi-fluorescent connectivity data (www.MouseConnectome.org).Additional MOB injections and injections of the accessory olfactory bulb (AOB), anterior olfactory nucleus (AON), and other olfactory cortical areas gradually will be made available.Analysis of connections from different regions of the MOB revealed a novel, topographically arranged MOB projection roadmap, demonstrated disparate MOB connectivity with anterior versus posterior piriform cortical area (PIR), and exposed some novel aspects of well-established cortical olfactory projections.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neuro Imaging, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, CA, USA.

ABSTRACT
We introduce the first open resource for mouse olfactory connectivity data produced as part of the Mouse Connectome Project (MCP) at UCLA. The MCP aims to assemble a whole-brain connectivity atlas for the C57Bl/6J mouse using a double coinjection tracing method. Each coinjection consists of one anterograde and one retrograde tracer, which affords the advantage of simultaneously identifying efferent and afferent pathways and directly identifying reciprocal connectivity of injection sites. The systematic application of double coinjections potentially reveals interaction stations between injections and allows for the study of connectivity at the network level. To facilitate use of the data, raw images are made publicly accessible through our online interactive visualization tool, the iConnectome, where users can view and annotate the high-resolution, multi-fluorescent connectivity data (www.MouseConnectome.org). Systematic double coinjections were made into different regions of the main olfactory bulb (MOB) and data from 18 MOB cases (~72 pathways; 36 efferent/36 afferent) currently are available to view in iConnectome within their corresponding atlas level and their own bright-field cytoarchitectural background. Additional MOB injections and injections of the accessory olfactory bulb (AOB), anterior olfactory nucleus (AON), and other olfactory cortical areas gradually will be made available. Analysis of connections from different regions of the MOB revealed a novel, topographically arranged MOB projection roadmap, demonstrated disparate MOB connectivity with anterior versus posterior piriform cortical area (PIR), and exposed some novel aspects of well-established cortical olfactory projections.

No MeSH data available.


Related in: MedlinePlus

Stratification of MOBgr and differential connectivity patterns of PIRa and PIRp with MOB. Injections in deep MOBgr (A) retrogradely label neurons in both MA and PIRp (B), while injections in MOBmi (C) label only MA neurons and not PIRp (D). PHAL injections into PIRp (E) label axons only in deep MOBgr (F), a pattern that is preserved in posterior sections (G,H). Note the distance from CTb labeled mitral cells and PHAL labeled fibers in G,H indicated by a red bar. PIRa projects to MOBmi and more superficial MOBgr (I,J), which is also apparent in posterior MOBgr (K,L). Note the distance between FG labeled mitral cells and PHAL labeled fibers. (M–P) are magnified images from (J) showing PHAL-labeled terminal boutons from PIRa contacting FG-labeled mitral cells. White arrows indicate magnified cells in top right corner of image. Scale bar 200 μm (A–D,F–L); 500 μm (E); 20 μm (M–P). Case numbers SW101215-05A (A,B), SW110607-05A (C,D); SW110403-01A (E–H), SW110616-04A (I–L). Abbreviations: MA, magnocellular nucleus; PIRp, posterior piriform area; PIRa, anterior piriform area; aco, anterior commissure olfactory limb; MOBmi, MOB mitral cell layer; gr, granule layer of MOB; AONe, external anterior olfactory nucleus.
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Figure 7: Stratification of MOBgr and differential connectivity patterns of PIRa and PIRp with MOB. Injections in deep MOBgr (A) retrogradely label neurons in both MA and PIRp (B), while injections in MOBmi (C) label only MA neurons and not PIRp (D). PHAL injections into PIRp (E) label axons only in deep MOBgr (F), a pattern that is preserved in posterior sections (G,H). Note the distance from CTb labeled mitral cells and PHAL labeled fibers in G,H indicated by a red bar. PIRa projects to MOBmi and more superficial MOBgr (I,J), which is also apparent in posterior MOBgr (K,L). Note the distance between FG labeled mitral cells and PHAL labeled fibers. (M–P) are magnified images from (J) showing PHAL-labeled terminal boutons from PIRa contacting FG-labeled mitral cells. White arrows indicate magnified cells in top right corner of image. Scale bar 200 μm (A–D,F–L); 500 μm (E); 20 μm (M–P). Case numbers SW101215-05A (A,B), SW110607-05A (C,D); SW110403-01A (E–H), SW110616-04A (I–L). Abbreviations: MA, magnocellular nucleus; PIRp, posterior piriform area; PIRa, anterior piriform area; aco, anterior commissure olfactory limb; MOBmi, MOB mitral cell layer; gr, granule layer of MOB; AONe, external anterior olfactory nucleus.

Mentions: Injections made into the MOBgr revealed unique connections of the MOB with the anterior and posterior PIR. FG injections encompassed within the dorsal deep MOBgr (Figure 7A) result in back-labeled neurons both in the posterior PIR (PIRp) and magnocellular nucleus (MA; Figure 7B). FG injections in the MOBmi that encroach slightly onto the superficial granular layer (Figure 7C) label neurons only in the MA, not the PIRp (Figure 7D). This suggests that the MA projects to both MOBgr and MOBmi, but that the PIRp projects only to the deep MOBgr. Corroborating this connection, PHAL/CTb injections in the PIRp (Figure 7E) result in labeled terminals solely in the deep MOBgr (Figure 7F), a pattern that is preserved in posterior MOBgr regions (Figures 7G,H). PIRp CTb injections confirm that cells in the entire MOBmi project back to the PIRp (Figures 7F–H). Together, the data suggest a connection chain from the MOBmi→PIRp→deep MOBgr. PHAL injections in the anterior PIR (PIRa) specifically innervate the superficial MOBgr layers and the MOBmi (Figures 7I,J,M–P). This pattern also is preserved in more posterior regions of the MOB (Figures 7K,L) and suggests a neural chain from MOBmi→PIRa→MOBmi/superficial MOBgr. Combined, these results demonstrate that (a) the MOBgr can be stratified into superficial and deep layers and (b) the PIRa and PIRp show differential connectivity patterns to the MOB, namely that the PIRa projects to the superficial MOBgr and MOBmi, while PIRp projects to deep MOBgr and avoids the MOBmi (Figure 8). This distinct connectivity of the PIRa and PIRp possibly has important implications for their roles in MOB activation (see “Discussion”).


Comprehensive connectivity of the mouse main olfactory bulb: analysis and online digital atlas.

Hintiryan H, Gou L, Zingg B, Yamashita S, Lyden HM, Song MY, Grewal AK, Zhang X, Toga AW, Dong HW - Front Neuroanat (2012)

Stratification of MOBgr and differential connectivity patterns of PIRa and PIRp with MOB. Injections in deep MOBgr (A) retrogradely label neurons in both MA and PIRp (B), while injections in MOBmi (C) label only MA neurons and not PIRp (D). PHAL injections into PIRp (E) label axons only in deep MOBgr (F), a pattern that is preserved in posterior sections (G,H). Note the distance from CTb labeled mitral cells and PHAL labeled fibers in G,H indicated by a red bar. PIRa projects to MOBmi and more superficial MOBgr (I,J), which is also apparent in posterior MOBgr (K,L). Note the distance between FG labeled mitral cells and PHAL labeled fibers. (M–P) are magnified images from (J) showing PHAL-labeled terminal boutons from PIRa contacting FG-labeled mitral cells. White arrows indicate magnified cells in top right corner of image. Scale bar 200 μm (A–D,F–L); 500 μm (E); 20 μm (M–P). Case numbers SW101215-05A (A,B), SW110607-05A (C,D); SW110403-01A (E–H), SW110616-04A (I–L). Abbreviations: MA, magnocellular nucleus; PIRp, posterior piriform area; PIRa, anterior piriform area; aco, anterior commissure olfactory limb; MOBmi, MOB mitral cell layer; gr, granule layer of MOB; AONe, external anterior olfactory nucleus.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 7: Stratification of MOBgr and differential connectivity patterns of PIRa and PIRp with MOB. Injections in deep MOBgr (A) retrogradely label neurons in both MA and PIRp (B), while injections in MOBmi (C) label only MA neurons and not PIRp (D). PHAL injections into PIRp (E) label axons only in deep MOBgr (F), a pattern that is preserved in posterior sections (G,H). Note the distance from CTb labeled mitral cells and PHAL labeled fibers in G,H indicated by a red bar. PIRa projects to MOBmi and more superficial MOBgr (I,J), which is also apparent in posterior MOBgr (K,L). Note the distance between FG labeled mitral cells and PHAL labeled fibers. (M–P) are magnified images from (J) showing PHAL-labeled terminal boutons from PIRa contacting FG-labeled mitral cells. White arrows indicate magnified cells in top right corner of image. Scale bar 200 μm (A–D,F–L); 500 μm (E); 20 μm (M–P). Case numbers SW101215-05A (A,B), SW110607-05A (C,D); SW110403-01A (E–H), SW110616-04A (I–L). Abbreviations: MA, magnocellular nucleus; PIRp, posterior piriform area; PIRa, anterior piriform area; aco, anterior commissure olfactory limb; MOBmi, MOB mitral cell layer; gr, granule layer of MOB; AONe, external anterior olfactory nucleus.
Mentions: Injections made into the MOBgr revealed unique connections of the MOB with the anterior and posterior PIR. FG injections encompassed within the dorsal deep MOBgr (Figure 7A) result in back-labeled neurons both in the posterior PIR (PIRp) and magnocellular nucleus (MA; Figure 7B). FG injections in the MOBmi that encroach slightly onto the superficial granular layer (Figure 7C) label neurons only in the MA, not the PIRp (Figure 7D). This suggests that the MA projects to both MOBgr and MOBmi, but that the PIRp projects only to the deep MOBgr. Corroborating this connection, PHAL/CTb injections in the PIRp (Figure 7E) result in labeled terminals solely in the deep MOBgr (Figure 7F), a pattern that is preserved in posterior MOBgr regions (Figures 7G,H). PIRp CTb injections confirm that cells in the entire MOBmi project back to the PIRp (Figures 7F–H). Together, the data suggest a connection chain from the MOBmi→PIRp→deep MOBgr. PHAL injections in the anterior PIR (PIRa) specifically innervate the superficial MOBgr layers and the MOBmi (Figures 7I,J,M–P). This pattern also is preserved in more posterior regions of the MOB (Figures 7K,L) and suggests a neural chain from MOBmi→PIRa→MOBmi/superficial MOBgr. Combined, these results demonstrate that (a) the MOBgr can be stratified into superficial and deep layers and (b) the PIRa and PIRp show differential connectivity patterns to the MOB, namely that the PIRa projects to the superficial MOBgr and MOBmi, while PIRp projects to deep MOBgr and avoids the MOBmi (Figure 8). This distinct connectivity of the PIRa and PIRp possibly has important implications for their roles in MOB activation (see “Discussion”).

Bottom Line: To facilitate use of the data, raw images are made publicly accessible through our online interactive visualization tool, the iConnectome, where users can view and annotate the high-resolution, multi-fluorescent connectivity data (www.MouseConnectome.org).Additional MOB injections and injections of the accessory olfactory bulb (AOB), anterior olfactory nucleus (AON), and other olfactory cortical areas gradually will be made available.Analysis of connections from different regions of the MOB revealed a novel, topographically arranged MOB projection roadmap, demonstrated disparate MOB connectivity with anterior versus posterior piriform cortical area (PIR), and exposed some novel aspects of well-established cortical olfactory projections.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neuro Imaging, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, CA, USA.

ABSTRACT
We introduce the first open resource for mouse olfactory connectivity data produced as part of the Mouse Connectome Project (MCP) at UCLA. The MCP aims to assemble a whole-brain connectivity atlas for the C57Bl/6J mouse using a double coinjection tracing method. Each coinjection consists of one anterograde and one retrograde tracer, which affords the advantage of simultaneously identifying efferent and afferent pathways and directly identifying reciprocal connectivity of injection sites. The systematic application of double coinjections potentially reveals interaction stations between injections and allows for the study of connectivity at the network level. To facilitate use of the data, raw images are made publicly accessible through our online interactive visualization tool, the iConnectome, where users can view and annotate the high-resolution, multi-fluorescent connectivity data (www.MouseConnectome.org). Systematic double coinjections were made into different regions of the main olfactory bulb (MOB) and data from 18 MOB cases (~72 pathways; 36 efferent/36 afferent) currently are available to view in iConnectome within their corresponding atlas level and their own bright-field cytoarchitectural background. Additional MOB injections and injections of the accessory olfactory bulb (AOB), anterior olfactory nucleus (AON), and other olfactory cortical areas gradually will be made available. Analysis of connections from different regions of the MOB revealed a novel, topographically arranged MOB projection roadmap, demonstrated disparate MOB connectivity with anterior versus posterior piriform cortical area (PIR), and exposed some novel aspects of well-established cortical olfactory projections.

No MeSH data available.


Related in: MedlinePlus