June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Diffusion fMRI of mouse optic nerve with antidromic electrical stimulation
Author Affiliations & Notes
  • Tsen-Hsuan Lin
    Raiology, Washington University School of Medicine, St. Louis, Missouri, United States
  • William M Spees
    Raiology, Washington University School of Medicine, St. Louis, Missouri, United States
    The Hope Center for Neurological Disorders, Washington University School of Medicine, ST. Louis, Missouri, United States
  • Michael Wallendorf
    Biostatistics, Washington University School of Medicine, ST. Louis, Missouri, United States
  • Yen-Yu Ian Shih
    Neurology, The University of North Carolina in Chapel Hill, Chapel Hill, North Carolina, United States
  • Anne Cross
    Neurology, Washington University School of Medicine, ST. Louis, Missouri, United States
    The Hope Center for Neurological Disorders, Washington University School of Medicine, ST. Louis, Missouri, United States
  • Sheng-Kwei Song
    Raiology, Washington University School of Medicine, St. Louis, Missouri, United States
    The Hope Center for Neurological Disorders, Washington University School of Medicine, ST. Louis, Missouri, United States
  • Footnotes
    Commercial Relationships   Tsen-Hsuan Lin, National Multiple Sclerosis Society (E); William Spees, None; Michael Wallendorf, None; Yen-Yu Shih, None; Anne Cross, None; Sheng-Kwei Song, USA Patent Serial No. 61-345,367 (P)
  • Footnotes
    Support  NIH R01-NS047592, P01-NS059560, U01-EY025500, NMSS RG 5258-A-5 and RG-1507-05315
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 3099. doi:
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    • Get Citation

      Tsen-Hsuan Lin, William M Spees, Michael Wallendorf, Yen-Yu Ian Shih, Anne Cross, Sheng-Kwei Song; Diffusion fMRI of mouse optic nerve with antidromic electrical stimulation. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3099.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Previously, we successfully reported diffusion fMRI (dfMRI) to assess axonal activation (decreased ADC, apparent diffusion coefficient perpendicular to axon tracts) with visual stimulation in healthy and experimental autoimmune encephalomyelitis mouse optic nerves (ON). In this study, we antidromically stimulated ON using tungsten microelectrodes implanted at LGN during dfMRI. This technique allows direct interrogation of ON function without confounding factors from the retina.

Methods : A 35- or 50-µm diameter tungsten electrode was implanted at right LGN of C57BL/6 mice (n=15) stimulated with biphasic square-waves of 5 or 10 Hz, 10Vp-p, 50- and 100-ms pulse width. MRI scans of ON were performed on a 4.7-T small-animal MR scanner using a multiple-echo spin-echo imaging sequence with: TR=1.5 s, TE=34.4 ms, inter-echo delay=18.2 ms, in-plane resolution=78 × 78 µm2, and slice thickness=1.3 mm. A pair of diffusion-weighted image (DWI), perpendicular to ON, was acquired with b-value=0.1 and 1.4 ms/µm2, δ=5 ms, and Δ=18 ms. Acquisition time was 12.8 minute for each pair of DWI.

Results : Electrical stimulation of right LGN lead to left ON ADC decrease without affecting the right ON. We observed a 15% and 19% of ADC decrease with 10Hz stimulation using 35- and 50-µm diameter tungsten wires, respectively. A 19% and 24% ADC decrease was seen with 10 and 5 Hz stimulation using 50-µm electrode.

Conclusions : DfMRI with electrical stimulation in mouse ON bypassing the retina input provides a direct measure to assess axonal function.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Figure 1 Tungsten electrode was implanted at right LGN (red arrows). Left ON ADC decreased during electrical stimulation.

Figure 1 Tungsten electrode was implanted at right LGN (red arrows). Left ON ADC decreased during electrical stimulation.

 

Figure 2 Normalized (A) and raw ADC (B) with different stimulation parameters.
* indicates p < 0.05, comparing to its baseline

Figure 2 Normalized (A) and raw ADC (B) with different stimulation parameters.
* indicates p < 0.05, comparing to its baseline

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