Jordan Davies and Dr. Scott Steffensen, Neuroscience

Introduction

The goal in my proposal was to study the effects of light stimulation in human brains on the action of the neurotransmitter dopamine (DA) within the nucleus accumbens (NAc), in order to determine its efficacy as a non-invasive method for inducing long-term potentiation of dopamine neurons, restoring homeostasis, and its possible use in clinical treatment for addiction. It was dependent upon research that was being done on mice in Dr. Steffensen’s lab to determine the optimum frequency and wavelength of light stimulation to bring baseline dopamine levels back up to normal. Unfortunately, there haven’t been any conclusive results that merit moving the principles onto human testing. In order to avoid unethical and inappropriate testing, we had to shift our focus to a different, but similar project.

The new project worked off an observation called binocular rivalry. This occurs when two images are on a screen simultaneously, but one in red and one in green. When the subject wears glasses with one lens that is red and one that is green, they only perceive one image at a time. One eye, and the associated visual cortex, is seeing one of the pictures, and the other eye and associated visual cortex is seeing the other at the same time, but the perception they receive is of only one picture. The mind will then alternate between the two images at a rate of about 15-20 times per minute for healthy subjects. An interesting observation has been made with subjects who struggle with addiction, that they alternate between the two images at a much slower rate. This could possibly be due to the chronically low dopamine levels that influence dopamine’s role in the eyes to perceive certain colors.

If conclusive results can be found that show the significantly slower alternation rate in addicts is linked to the extent of their addiction, it could lead to a very inexpensive clinical tool to measure extent of addiction. It could, in essence, be considered a biomarker for addiction.

Materials/Methods

The data for this study was collected a few years ago in a project conducted by Joann Petrie and Scott Steffensen, but the data had yet to be analyzed. The subjects consisted of 30 male BYU students, 30 female BYU students, and 15 opiate addicts recruited by Joann Petrie from a community-based high intensity residential substance abuse and detoxification treatment program.

The binocular rivalry trial lasted 2 minutes, in which the subjects were instructed to press the number 1 on the keypad during one percept (e.g. when they saw the green image), and the number 2 on the keypad during the other percept (e.g. when they saw the red image). During the trial they were hooked up to an EEG device which recorded brain activity in the context of the image alternations. The brain activity and subject responses were recorded on Net Station. Net Station is also being used to clean up the data using baseline correction, ocular artifact removal, and filtering. The data will then be segmented using Net Station into the two separate precepts according to the subjects’ responses. After segmentation, MatLab is being used to provide spectral analysis in a topo plot of the brain. In short, this data is being analyzed to determine alternating brain function that may correspond with the percept alternations, along with observing alternation rate differences between normal and addict subjects.

Results

Analysis is ongoing, and there are no hard results yet. Initial analysis may indicate slower alternation rate for addicts, and differing brain activity between percepts.

Discussion

Although we couldn’t ethically continue with the proposed project, it is still a focus in the Steffensen lab and there is hope that the light stimulation trials in mice will yield conclusive enough evidence to warrant a project done on humans in the near future. In the mean time, the current project on binocular rivalry is ongoing in the data analysis, and at an initial look is providing encouraging findings. It has the potential to yield a biomarker for addiction that clinicians can use in treatment and diagnosis in the future