Thesis Defense Announcement
To:  The George Mason University Community

Candidate: Allison Bolton
Program: M.S. in Biology
Date:   Thursday December 10, 2015 
Time:   2:00 PM
Place:  George Mason University
Science & Tech (Prince William) Campus
            Occoquan Bldg. #312-G           
Title: "Improved Monitoring of Single Unit Activity in Neuronal Circuits by Localization of a Hybrid Optical Voltage Sensor to the Soma "

Thesis Director: Dr. Theodore Dumas
Committee Members: Dr. Donald Seto, Dr. Kylene Kehn-Hall
A copy of the thesis will be available in the Gateway Library.  All are invited to attend the defense.

Electrical activity of neurons traditionally has been measured using electrophysiological methods. In this manner, numerous important concepts regarding relationships between activity dynamics in neuronal circuits and cognitive abilities have been resolved. However, a technological ceiling has been reached in trying to apply electrophysiological recording to monitor large numbers of neurons simultaneously as an animal performs in a behavioral task, limiting further discoveries. Voltage- and calcium-sensitive dyes (VSDs) proved successful in increasing recording throughput, providing the impetus to develop genetically encoded probes. Genetically encoded voltage and calcium sensors allowed for cellular specificity and a few constructs displayed the temporal resolution to track action potentials in neural circuits, including the hybrid voltage sensor (hVoS) system. Limitations in the signal to noise ratio due to cell-wide expression led us to develop a novel hVoS sensor (termed Firefluo) where the fluorophore is fused to the amino terminus of the SK1 potassium channel, directing surface expression to the neuronal soma only. It is believed that Firefluo will greatly increase the signal to noise ratio for action potential dynamics in large neuronal populations by removing background noise from neuronal processes and more tightly coupling the fluorophore to action potentials due to is soma localization.