Constructing a Chronic Neural Ensemble Recording System

Undergraduate #162
Discipline: Biological Sciences
Subcategory: Social Sciences/Psychology/Economics

Christian E. Ayon Garcia - University of Wisconsin Whitewater
Co-Author(s): Thomas Geiser, University of Wisconsin Whitewater, Wisconsin, Whitewater; Rachel Lensing, University of Wisconsin Whitewater, Wisconsin, Whitewater; Ryan Honeck, University of Wisconsin Whitewater, Wisconsin, Whitewater

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The extended amygdala is a basal forebrain macrostructure that has been suggested to mediate appetitive behavior, such as reproduction, reward learning and drug addiction, along with aversive states such as aggression, fear, anxiety and stress. Many studies have investigated the extended amygdala on circuital and molecular levels through various methods, but there haven’t been studies using an electrophysiological system. The goal of this project is to record the extended amygdala activity while the rats respond to stimuli in a semi-natural environment. We hypothesize that the extended amygdala has a role in processing and determining whether a stimulus in the environment should be acted upon to promote survival or whether the animal should avoid the stimulus all together. In order to record the neural activity, the hardware and software components of the system must be fabricated or purchased. Our custom designed electrode, which will be implanted into the brain, is made up of eight, 42μm in diameter, tungsten wires. These wires are micro-soldered to connector pins that will mate with a commercial head stage amplifier and digitizer. The recorded neural data will then travel up a cable to a data acquisition board, which allows communication to and from the data acquisition interface on the computer. The interface is able to send triggering signals that will synchronize the recordings with a stimulus, along with adjustments of sampling rates and desired number of recording channels. The data is then transferred to software that deconstructs a seemingly arbitrary waveform, into separate neurons by guidelines, such as fire rates, amplitudes, and the use of spike sorting. These guidelines help determine neuronal type and behavioral outputs in response to stimuli. The data analysis software will also create peristimulus time histograms and will link video recordings of the rats with the data recordings. To allow free movement of the rats, maximum movement range, and full rotation, we constructed an environment topped with an X-Y stage.

Not Submitted

Funder Acknowledgement(s): Research Apprenticeship Program, Summer Undergraduate Research Fellowship, Faculty Initiative for Research/Scholarly/Creative excellent, Ganser Biology Research Award

Faculty Advisor: Dr. Meg Waraczynski, waraczym@uww.edu

Role: Since I joined the the neuro team for Constructing a Chronic Neural Ensemble Recording System freshman year, my main focus was to develop an electrode with the lowest impedance possible, which would allow us to record the most accurate data. I began by practicing and developing my micro soldering techniques and over time I gradually continued improving my micro soldering. My next task was to complete the first prototype of the electrode. At this point we haven't had it fully functional but will continue to develop this first electrode.