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4D Functional Imaging in Freely Moving Animals

4D Functional Imaging in Freely Moving Animals. Randall L. Barbour SUNY Downstate Medical Center. OSA Biomedical Optics Meeting Fort Lauderdale, FL, March 20, 2005. Higher. Minimal. Lower. Maximal. Levels of Analysis in Biological Investigation. Cell Free Preparation. Cell Culture.

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4D Functional Imaging in Freely Moving Animals

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  1. 4D Functional Imaging in Freely Moving Animals Randall L. Barbour SUNY Downstate Medical Center OSA Biomedical Optics Meeting Fort Lauderdale, FL, March 20, 2005

  2. Higher Minimal Lower Maximal Levels of Analysis in Biological Investigation Cell Free Preparation Cell Culture Organotypic Culture Degree of Control Phenomenological Complexity Perfused Organ Anesthetized Animal Restrained Animal Freely Moving Animal R.L. Barbour

  3. Why Freely Moving Animals? • Only preparation capable of expressing the full behavioral repertoire of a species. • Aggression • Mating • Fear • Perceptual • Locomotor • Manipulative • Current imaging tools require investigation on restrained/anesthetized animals. • PET/SPECT • MR-fMRI • MEG R.L. Barbour

  4. Why Optical Methods? • Inexpensive, compact instrumentation • High intrinsic sensitivity • Deep tissue penetration • Fast data collection • Easily overlaid on other sensing technologies • Opportunity for dynamic studies R.L. Barbour

  5. Objectives of current study 1. Determine feasibility of continuous functional imaging in freely moving animals while simultaneously recording behavioral, neural and hemodynamic responses. 2. Identify the temporal and spatial dependence of the vascular response as gated to EEG (theta) rhythms. R.L. Barbour

  6. Photo of 9s x 32d imager FRONT Detector channels Timing BACK Power supplies Laser controllers Optical switch Source fiber terminal Lasers / optics R.L. Barbour

  7. Computer w/ frame grabber Laptop computer Figure 12. Schematic of Optical Imaging-EEG-Behavior Monitoring System. DYNOT compact system synchronization Video cam Electro- physiology recording system Optical tether Computer Electrical tether Environmental chamber Head stage w/ Tracking LED Arena w/ animal Schematic of System Setup R.L. Barbour

  8. Optical Fibers 1.8 mm dia. Male part Tracking LED’s Female part Connecting Clips Electrode leads Dual mode optical-EEG measuring head Optical array: 4 source x 16 detector Dual wavelength: 760, 830 nm Framing rate: 17 Hz EEG: 12, 0.1mm diameter electrodes R.L. Barbour

  9. Male Part Optical fiber extension element EEG Electrodes Grounding wires Female Part Dual mode optical-EEG measuring head R.L. Barbour

  10. Olfactory bulbs Right Cortical Hemisphere Receiving Fiber Cerebellum EEG Electrodes Left Cortical Hemisphere Hippocampus Rat Brain Anatomy with Optical-EEG Overlay Transmitting/receiving Fiber R.L. Barbour

  11. Rat with attached helmet and tether R.L. Barbour

  12. Movie of freely moving rat with attached tether R.L. Barbour

  13. Large Irregular Activity Amplitude Time Theta Amplitude Time Hippocampal EEG Rhythms R.L. Barbour

  14. Optical Image Time Series EEG Time Series Time Non-Theta Theta Non-Theta Theta Data Analysis-Integration R.L. Barbour

  15. FEM Mesh for Rat Brain Model S-D Geometry (3D View) FEM Mesh (3D View) 7-compartment model of rat head anatomy obtained from CT scan. 2488 FEM nodes. From Bluestone et al. 2004. R.L. Barbour

  16. Approach • Capture simultaneous: EEG, behavior and dual wavelength tomographic time-series. • Compute volumetric images • Determine temporal/spatial dependence of Hb on EEG/behavior states. R.L. Barbour

  17. RESULTS • Time dependence of spatially integrated findings. • Spatial dependence of temporally integrated findings. R.L. Barbour

  18. Exp. 1: EEG-Gated Hb Spatial Mean Time Series Hboxy Hbdeoxy Hbtot HbO2 Sat Red – Non-Theta Green – Theta (animal moving) R.L. Barbour

  19. Exp 1: Time Averaged-Whole Brain EEG-Gated Hemoglobin Response R.L. Barbour

  20. P-value HbOxy HbDeoxy HbTotal HbSat Stationarity of EEG-Gated Hb Response .. …… R.L. Barbour

  21. Figure 8. Hb response as a function of removal of fraction of initial period. Time Lag of Hb Response R.L. Barbour

  22. Spatially Integrated findings of vascular response to theta rhythm • Increased Hboxy • Decreased Hbdeoxy • Increase Hbtot • Increased HbO2Sat • i.e., BOLD effect R.L. Barbour

  23. EEG-Gated Hb Response Rat 1 Session 1 (Sec 1 - 4) B A Rat 1 Session 2 (Sec 1 - 4) HbOxy HbDeoxy HbTot HbSat Rat 2 Session 2 (Sec 1 - 4) Rat 2 Session 1 (Sec 1 - 4) C D HbOxy HbDeoxy HbTot HbSat R.L. Barbour

  24. Time Dependence of Gated Response Four Sessions Combined (Sec 1 - 4) Four sessions combined (0-1 sec) HbOxy HbDeoxy HbTot HbSat R.L. Barbour

  25. Spatial dependence • Spatial response is reproducible across trials. • Positive, negative and mixed BOLD effects are mainly spatially distinct. R.L. Barbour

  26. Autoregulatory dependent hemoglobin states R.L. Barbour

  27. Spatial Mean Time Series for Autoregulatory State 4 (Balanced) Pixel No Hboxy+ Hbdeoxy+ Hbtot+ R.L. Barbour

  28. Spatial Mean Time Series for Autoregulatory State 5 (Uncompensated oxygen excess) Pixel No Hboxy+ Hbdeoxy- Hbtot+ R.L. Barbour

  29. Spatial Mean Time Series for Autoregulatory State 6 (Compensated oxygen excess) Pixel No Hboxy+ Hbdeoxy- Hbtot- R.L. Barbour

  30. Spatial dependence of autoregulatory response 4 5 Nose 6 3 1 2 R.L. Barbour

  31. Temporal Averaged Gated Maps of Hb States R.L. Barbour

  32. P-values for Theta vs. Non-theta for Autoregulatory dependent hemoglobin states R.L. Barbour

  33. Time-integrated Hb states: Theta 4 5 3 6 Composite 1 2 R.L. Barbour

  34. Time-integrated Hb states: Non-Theta 4 5 3 6 Composite 1 2 R.L. Barbour

  35. Conclusions • Real-time recording of hemodynamic, EEG and behavorial responses is technically feasible in freely moving animals. • Hemodynamic response to theta rhythms are reproducible and spatially distinct. • Method provides for assessment of temporal-spatial dynamics of autoregulatory response to neural activation. R.L. Barbour

  36. Future Considerations • Imaging under defined behavioral paradigms to ascertain localizability of EEG dependent hemodynamic responses. • Influence of pharmacoactive agents on measured responses. • Technological improvements: >S-D pairs, wavelengths, etc. • Development of human compatible system. R.L. Barbour

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