Ophthalmology and Pyschology
Project: In Vivo Imaging of Axonal Transport in the Visual Pathway Using Manganese-Enhanced Magnetic Resonance Imaging
Axons are the information highways that connect the 100 billion neurons and form the 100 trillion synapses in the human brain. These brain connections are lost as part of normal aging. The potential causes of such age-dependent loss include impaired axonal transport at the optic nerve head, mitochondrial dysfunction, atherosclerosis, and biomechanical damage. Compatible with this age-related vulnerability, anterior ischemic optic neuropathy, the most common acute optic nerve damage in patients older than 50 years old, and glaucoma, the most common chronic optic neuropathy in the world, predominantly occur in older adults. In this project, we will develop manganese-enhanced magnetic resonance imaging (MRI) as a tool to study axonal transport in the central nervous system in vivo. The paramagnetic dye manganese chloride is injected intravitreally, taken up into the retinal ganglion cells, and transported anterogradely down the optic nerve axons to the superior colliculus (SC) and the lateral geniculate nucleus (LGN) in an activity-dependent manner. This technique will allow characterization of the functional and anatomical properties of the visual pathway in the normal murine visual pathway and following experimental anterior ischemic optic neuropathy (AION). We will also correlate MRI data with changes seen using in vivo retinal imaging techniques including confocal laser scanning ophthalmoscopy and spectral-domain optical coherence tomography.