Blood oxygenation level-dependent (BOLD) functional MRI of visual stimulation in the rat retina at 11.7 T

Bryan H.De La Garza, Eric R. Muir, Guang Li, Yen Yu I. Shih, Timothy Q. Duong

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Although optically based imaging techniques provide valuable functional and physiological information of the retina, they are mostly limited to the probing of the retinal surface and require an unobstructed light path. MRI, in contrast, could offer physiological and functional data without depth limitation. Blood oxygenation level-dependent functional MRI (BOLD fMRI) of the thin rat retina is, however, challenging because of the need for high spatial resolution, and the potential presence of eye movement and susceptibility artifacts. This study reports a novel application of high-resolution (111×111×1000 μm3) BOLD fMRI of visual stimulation in the anesthetized rat retina at 11.7 T. A high-field MRI scanner was utilized to improve the signal-to-noise ratio, spatial resolution and BOLD sensitivity. Visual stimuli (8Hz diffuse achromatic light) robustly increased BOLD responses in the retina [5.0±0.8% from activated pixels and 3.1±1.1% from the whole-retina region of interest (mean±SD), n=12 trials on six rats, p<0.05 compared with baseline]. Some activated pixels were detected surrounding the pupil and ciliary muscle because of accommodation reflex to visual stimuli, and were reduced with atropine and phenylephrine eye drops. BOLD fMRI scans without visual stimulations showed no significantly activated pixels (whole-retina BOLD changes were 0.08±0.34%, n=6 trials on five rats, not statistically different from baseline, p>0.05). BOLD fMRI of visual stimulation has the potential to provide clinically relevant data to probe hemodynamic neurovascular coupling and dysfunction of the retina with depth resolution.

Original languageEnglish (US)
Pages (from-to)188-193
Number of pages6
JournalNMR in Biomedicine
Issue number2
StatePublished - Feb 2011
Externally publishedYes


  • Blood flow
  • Choroid
  • Dark and light adaptation
  • High magnetic field
  • High-resolution fMRI
  • Laminar specificity

ASJC Scopus subject areas

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Spectroscopy


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