Journal of Molecular Neuroscience

, Volume 53, Issue 4, pp 553–561 | Cite as

Study of the Spatial Correlation Between Neuronal Activity and BOLD fMRI Responses Evoked by Sensory and Channelrhodopsin-2 Stimulation in the Rat Somatosensory Cortex

  • Nan Li
  • Peter van Zijl
  • Nitish Thakor
  • Galit Pelled


In this work, we combined optogenetic tools with high-resolution blood oxygenation level-dependent functional MRI (BOLD fMRI), electrophysiology, and optical imaging of cerebral blood flow (CBF), to study the spatial correlation between the hemodynamic responses and neuronal activity. We first investigated the spatial and temporal characteristics of BOLD fMRI and the underlying neuronal responses evoked by sensory stimulations at different frequencies. The results demonstrated that under dexmedetomidine anesthesia, BOLD fMRI and neuronal activity in the rat primary somatosensory cortex (S1) have different frequency–dependency and distinct laminar activation profiles. We then found that localized activation of channelrhodopsin-2 (ChR2) expressed in neurons throughout the cortex induced neuronal responses that were confined to the light stimulation S1 region (<500 μm) with distinct laminar activation profile. However, the spatial extent of the hemodynamic responses measured by CBF and BOLD fMRI induced by both ChR2 and sensory stimulation was greater than 3 mm. These results suggest that due to the complex neurovascular coupling, it is challenging to determine specific characteristics of the underlying neuronal activity exclusively from the BOLD fMRI signals.


Hemodynamic fMRI Optical imaging Optogenetics Somatosensory cortex 



The authors would like to thank Dr. Karl Deisseroth for kindly providing the ChR2 plasmids, Drs. Assaf Gilad and Piotr Walczak for helping with virus preparation, and John Downey and Yang Han for assisting with the animal imaging. This work was supported by NIH/NINDS R01NS072171 (G.P.).


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Nan Li
    • 1
    • 2
  • Peter van Zijl
    • 1
    • 2
  • Nitish Thakor
    • 3
  • Galit Pelled
    • 1
    • 2
  1. 1.F. M. Kirby Center for Functional Brain ImagingKennedy Krieger InstituteBaltimoreUSA
  2. 2.The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR ResearchJohns Hopkins University School of MedicineBaltimoreUSA
  3. 3.The Department of Biomedical EngineeringJohns Hopkins University School of MedicineBaltimoreUSA

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