Assessment of neural activity in awake and behaving animals is notoriously complex, and often challenging for undergraduate students to implement in their research. In the last two years, a new technology has emerged that has dramatically simplified the assessment of neural activity in awake behaving animals, called Fiber Photometry, making it potentially useful in an undergraduate experiential learning setting. In brief, Fiber Photometry works by making neurons emit light when they are active. By implanting a miniscule fiber-optic cable above the affected neurons, we can then measure the activity of that region by measuring its luminance. Brighter periods of time indicate periods of greater neural activity. Given the newness of this method to the field, the purpose of this project was to develop and validate fiber photometry to quantify neural activity here at Miami. Our first attempt to pilot this method involved the injection of a designer virus that caused neurons to express the protein dLight, which responds to the neurotransmitter dopamine (DA). After recovery, light emission was tested after electrical stimulation and natural reward; however, no light emission was found. In our second attempt, we switched to a different virus, which caused expression of GCaMP6f, a designer protein that responds to calcium, an indicator of general neural activity. However, again, no light emission was found. Our third attempt also used GCaMP6f, but tried a different brain region; however, this was also unsuccessful. Analysis of the tissue from this attempt suggested that viral-induced cell damage may have occurred. Therefore, in our 4th attempt, we reduced the virus concentration to reduce cell damage; however, this also resulted in no measurable light emission. Future attempts will further reduce viral concentration and inject larger volumes of virus to affect larger portions of the tissue. Once successful, these methods will be available to all Miami researchers, including students, and will position Miami to be at the forefront of neuroscience research.
Authors: Cayla Bodner, Griffin Betz
Faculty Advisor: Matthew S. McMurray, Psychology
Graduate Student Advisor: Danielle Tapp, Psychology
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