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Proceedings Paper

Mapping cell-specific functional connections in the mouse brain using ChR2-evoked hemodynamics (Conference Presentation)
Author(s): Adam Q. Bauer; Andrew Kraft; Grant A. Baxter; Michael Bruchas; Jin-Moo Lee; Joseph P. Culver

Paper Abstract

Functional magnetic resonance imaging (fMRI) has transformed our understanding of the brain’s functional organization. However, mapping subunits of a functional network using hemoglobin alone presents several disadvantages. Evoked and spontaneous hemodynamic fluctuations reflect ensemble activity from several populations of neurons making it difficult to discern excitatory vs inhibitory network activity. Still, blood-based methods of brain mapping remain powerful because hemoglobin provides endogenous contrast in all mammalian brains. To add greater specificity to hemoglobin assays, we integrated optical intrinsic signal(OIS) imaging with optogenetic stimulation to create an Opto-OIS mapping tool that combines the cell-specificity of optogenetics with label-free, hemoglobin imaging. Before mapping, titrated photostimuli determined which stimulus parameters elicited linear hemodynamic responses in the cortex. Optimized stimuli were then scanned over the left hemisphere to create a set of optogenetically-defined effective connectivity (Opto-EC) maps. For many sites investigated, Opto-EC maps exhibited higher spatial specificity than those determined using spontaneous hemodynamic fluctuations. For example, resting-state functional connectivity (RS-FC) patterns exhibited widespread ipsilateral connectivity while Opto-EC maps contained distinct short- and long-range constellations of ipsilateral connectivity. Further, RS-FC maps were usually symmetric about midline while Opto-EC maps displayed more heterogeneous contralateral homotopic connectivity. Both Opto-EC and RS-FC patterns were compared to mouse connectivity data from the Allen Institute. Unlike RS-FC maps, Thy1-based maps collected in awake, behaving mice closely recapitulated the connectivity structure derived using ex vivo anatomical tracer methods. Opto-OIS mapping could be a powerful tool for understanding cellular and molecular contributions to network dynamics and processing in the mouse brain.

Paper Details

Date Published: 19 April 2017
PDF: 1 pages
Proc. SPIE 10051, Neural Imaging and Sensing, 100510Y (19 April 2017); doi: 10.1117/12.2253100
Show Author Affiliations
Adam Q. Bauer, Washington Univ. School of Medicine in St. Louis (United States)
Andrew Kraft, Washington Univ. School of Medicine in St. Louis (United States)
Grant A. Baxter, Washington Univ. School of Medicine (United States)
Michael Bruchas, Washington Univ. School of Medicine (United States)
Jin-Moo Lee, Washington Univ. School of Medicine (United States)
Joseph P. Culver, Washington Univ. School of Medicine in St. Louis (United States)

Published in SPIE Proceedings Vol. 10051:
Neural Imaging and Sensing
Qingming Luo; Jun Ding, Editor(s)

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