Feedback processing is a key determinant of the decision-making process. During feedback processing, the outcomes of subjects’ responses are evaluated based on the outcome’s value and subjects’ expectations. These processes inform subjects’ future choices as they learn how to maximize reward and minimize punishment. Abnormalities in feedback processing are present in several psychiatric disorders, including obsessive-compulsive disorder (OCD), major depressive disorder (MDD), and substance abuse disorder (SUD).

The orbitofrontal cortex (OFC) is claimed as an important brain region in feedback processing across species. Studies in primates and rodents have mainly analyzed activities of individual neurons (single unit activity)/neuronal populations. One of the challenges in recording single unit activities is the cost of device and uncertainty of the yield and longevity of recording. In my master’s project, I have developed a single unit collection device that enables affordable collection of single unit activity in rat OFC and anterior cingulate cortex for an average of 12 weeks with a range from 5 to 24 weeks. Each device costs less than $100 U.S. dollars, and the technique can be easily applied to other superficial and deep brain regions.

Using our single unit probe design, we have collected single unit activities in OFC when rats performed a go/wait task. We have found that the activity OFC neurons were modulated during the period of reward/punishment evaluation and response preparation. Our findings are consistent with previous literature. We are in the progress of analyzing single unit activity with LFP activity through techniques such as spike-field coherence.