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J.D. Lindsey, M. Scadeng, J.G. Crowston, R. Weinreb; Quantitative Measurement of Mouse Optic Nerve Projections to the Brain in vivo . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3516.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate measurement of optic nerve projections to the mouse brain in vivo by magnetic resonance imaging following intraocular injection of manganese. Methods: Anesthetized Swiss white mice received 1 µl intracameral injection of 125–500 mM MnCl2 into the right eye. After eighteen hours, the mice were anesthetized with isofluorane and T1–weighted, spin–echo 3–dimensional data sets were acquired of the eyes and brain using a horizontal bore 7–Tesla magnetic resonance imager. Image intensity measurements were collected in the lateral geniculate nucleus (LGN), superior colliculus (SC), and the V1 area of visual cortex (V1–Ctx). For a normalization reference, measurements were collected in the masseter muscle (MM). To determine background intensities, the LGN, SC, V1–Ctx and MM were measured in mice that had received 1 µl of intranasal manganese. Results: Tracer signal was readily detected in the optic nerve, optic chiasm, ventral optic tract, LGN, the superficial layers of the SC, and the visual cortex. Image intensity relative to background was increased by 55±7% and 21±7% in left and right LGN, respectively; increased by 61±12% and 22±10% in left and right SC, respectively; and increased by 31±2 and 22±2% in left and right V1–Ctx, respectively (mean±SD, n = 3). Differences between the image intensity in the left and right LGN, SC, and V1–Ctx were significant (t–test, P = 0.004, 0.009, and 0.005, respectively). In repeated imaging sessions, the tracer signal remained bright for several days and gradually faded over the two weeks after injection. Conclusions: These results indicate that injection of manganese into the mouse eye yields reproducible increases of image signal in the major retinorecipient brain nuclei, as well as in V1–Ctx. These results support use of this method to evaluate optic nerve projections to the mouse brain in vivo.
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