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White BR, Padawer-Curry JA, Cohen AS, Licht DJ, Yodh AG. Brain segmentation, spatial censoring, and averaging techniques for optical functional connectivity imaging in mice. BIOMEDICAL OPTICS EXPRESS 2019; 10:5952-5973. [PMID: 31799057 PMCID: PMC6865125 DOI: 10.1364/boe.10.005952] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 09/05/2019] [Accepted: 09/13/2019] [Indexed: 05/25/2023]
Abstract
Resting-state functional connectivity analysis using optical neuroimaging holds the potential to be a powerful bridge between mouse models of disease and clinical neurologic monitoring. However, analysis techniques specific to optical methods are rudimentary, and algorithms from magnetic resonance imaging are not always applicable to optics. We have developed visual processing tools to increase data quality, improve brain segmentation, and average across sessions with better field-of-view. We demonstrate improved performance using resting-state optical intrinsic signal from normal mice. The proposed methods increase the amount of usable data from neuroimaging studies, improve image fidelity, and should be translatable to human optical neuroimaging systems.
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Affiliation(s)
- Brian R. White
- Division of Pediatric Cardiology, Department of Pediatrics, The Children’s Hospital of Philadelphia. 3401 Civic Center Blvd., Pediatric Cardiology - 8NW, Philadelphia, PA 19104, USA
| | - Jonah A. Padawer-Curry
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of Philadelphia. 3501 Civic Center Blvd., Philadelphia, PA 19104, USA
| | - Akiva S. Cohen
- Department of Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia. 3615 Civic Center Blvd., Abramson Research Center, Room 816-H, Philadelphia, PA 19104, USA
| | - Daniel J. Licht
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of Philadelphia. 3501 Civic Center Blvd., Philadelphia, PA 19104, USA
| | - Arjun G. Yodh
- Department of Physics and Astronomy, University of Pennsylvania. 3231 Walnut St., Philadelphia, PA 19104, USA
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Bauer AQ, Kraft AW, Baxter GA, Wright PW, Reisman MD, Bice AR, Park JJ, Bruchas MR, Snyder AZ, Lee JM, Culver JP. Effective Connectivity Measured Using Optogenetically Evoked Hemodynamic Signals Exhibits Topography Distinct from Resting State Functional Connectivity in the Mouse. Cereb Cortex 2018; 28:370-386. [PMID: 29136125 PMCID: PMC6057523 DOI: 10.1093/cercor/bhx298] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Indexed: 02/07/2023] Open
Abstract
Brain connectomics has expanded from histological assessment of axonal projection connectivity (APC) to encompass resting state functional connectivity (RS-FC). RS-FC analyses are efficient for whole-brain mapping, but attempts to explain aspects of RS-FC (e.g., interhemispheric RS-FC) based on APC have been only partially successful. Neuroimaging with hemoglobin alone lacks specificity for determining how activity in a population of cells contributes to RS-FC. Wide-field mapping of optogenetically defined connectivity could provide insights into the brain's structure-function relationship. We combined optogenetics with optical intrinsic signal imaging to create an efficient, optogenetic effective connectivity (Opto-EC) mapping assay. We examined EC patterns of excitatory neurons in awake, Thy1-ChR2 transgenic mice. These Thy1-based EC (Thy1-EC) patterns were evaluated against RS-FC over the cortex. Compared to RS-FC, Thy1-EC exhibited increased spatial specificity, reduced interhemispheric connectivity in regions with strong RS-FC, and appreciable connection strength asymmetry. Comparing the topography of Thy1-EC and RS-FC patterns to maps of APC revealed that Thy1-EC more closely resembled APC than did RS-FC. The more general method of Opto-EC mapping with hemoglobin can be determined for 100 sites in single animals in under an hour, and is amenable to other neuroimaging modalities. Opto-EC mapping represents a powerful strategy for examining evolving connectivity-related circuit plasticity.
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Affiliation(s)
- Adam Q Bauer
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Andrew W Kraft
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Grant A Baxter
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Patrick W Wright
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Matthew D Reisman
- Department of Physics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Annie R Bice
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Jasmine J Park
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Michael R Bruchas
- Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Abraham Z Snyder
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Jin-Moo Lee
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Neurology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Joseph P Culver
- Department of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA.,Department of Physics, Washington University School of Medicine, Saint Louis, MO 63110, USA
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Wright PW, Brier LM, Bauer AQ, Baxter GA, Kraft AW, Reisman MD, Bice AR, Snyder AZ, Lee JM, Culver JP. Functional connectivity structure of cortical calcium dynamics in anesthetized and awake mice. PLoS One 2017; 12:e0185759. [PMID: 29049297 PMCID: PMC5648115 DOI: 10.1371/journal.pone.0185759] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 09/19/2017] [Indexed: 11/30/2022] Open
Abstract
The interplay between hemodynamic-based markers of cortical activity (e.g. fMRI and optical intrinsic signal imaging), which are an indirect and relatively slow report of neural activity, and underlying synaptic electrical and metabolic activity through neurovascular coupling is a topic of ongoing research and debate. As application of resting state functional connectivity measures is extended further into topics such as brain development, aging and disease, the importance of understanding the fundamental physiological basis for functional connectivity will grow. Here we extend functional connectivity analysis from hemodynamic- to calcium-based imaging. Transgenic mice (n = 7) expressing a fluorescent calcium indicator (GCaMP6) driven by the Thy1 promoter in glutamatergic neurons were imaged transcranially in both anesthetized (using ketamine/xylazine) and awake states. Sequential LED illumination (λ = 454, 523, 595, 640nm) enabled concurrent imaging of both GCaMP6 fluorescence emission (corrected for hemoglobin absorption) and hemodynamics. Functional connectivity network maps were constructed for infraslow (0.009–0.08Hz), intermediate (0.08–0.4Hz), and high (0.4–4.0Hz) frequency bands. At infraslow and intermediate frequencies, commonly used in BOLD fMRI and fcOIS studies of functional connectivity and implicated in neurovascular coupling mechanisms, GCaMP6 and HbO2 functional connectivity structures were in high agreement, both qualitatively and also quantitatively through a measure of spatial similarity. The spontaneous dynamics of both contrasts had the highest correlation when the GCaMP6 signal was delayed with a ~0.6–1.5s temporal offset. Within the higher-frequency delta band, sensitive to slow wave sleep oscillations in non-REM sleep and anesthesia, we evaluate the speed with which the connectivity analysis stabilized and found that the functional connectivity maps captured putative network structure within time window lengths as short as 30 seconds. Homotopic GCaMP6 functional connectivity maps at 0.4–4.0Hz in the anesthetized states show a striking correlated and anti-correlated structure along the anterior to posterior axis. This structure is potentially explained in part by observed propagation of delta-band activity from frontal somatomotor regions to visuoparietal areas. During awake imaging, this spatio-temporal quality is altered, and a more complex and detailed functional connectivity structure is observed. The combined calcium/hemoglobin imaging technique described here will enable the dissociation of changes in ionic and hemodynamic functional structure and neurovascular coupling and provide a framework for subsequent studies of neurological disease such as stroke.
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Affiliation(s)
- Patrick W. Wright
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Lindsey M. Brier
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Adam Q. Bauer
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Grant A. Baxter
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Andrew W. Kraft
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Matthew D. Reisman
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Physics, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Annie R. Bice
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Abraham Z. Snyder
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jin-Moo Lee
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department Neurology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Joseph P. Culver
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri, United States of America
- * E-mail:
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