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High-Density Multi-Electrode Array (MEA) Recordings

Niraj Gupta, December 2022

During the Fall 2022 quarter, I had the privilege of doing a 10-week rotation in the Cognitive Control lab directed by Dr. Xiaomo Chen as a first-year Biomedical Engineering Ph.D. student. 


My main project for the quarter was to set up the recording system for Neuropixels probes. (Neuropixels probes are high-density multi-electrode arrays that allow us to record from hundreds of neurons simultaneously across different brain regions.) The lab will use this recording system in future experiments to investigate the neural mechanisms of selective visual attention within brain regions such as the Medial Frontal Cortex in Rhesus Macaque monkeys.  This project was a great challenge and a lot of fun as it required attention to detail, troubleshooting skills, and gave me exposure to a new recording technique that is revolutionizing how we approach neuroscience. 


In addition, I learned how to utilize spike sorting algorithms such as Kilosort which is ideal for processing very large datasets generated by the Neuropixels probes and learned common data analysis techniques to characterize neuronal behavior such as the Peristimulus Time Histogram. 


During my rotation, I submitted an NSF fellowship application with Dr. Xiaomo Chen who provided excellent guidance on writing a research plan with a strong hypothesis and clear aims. The plan seeks to identify a causal role of the Medial Frontal Cortex in visual attention driven by internal goals and will be tested first by using Neuropixels probes to characterize the population dynamics and organization of neurons in this brain region, and secondly by observing the causal effect of microstimulations in the Medial Frontal Cortex on voluntary attention. 


Thank you to Dr. Xiaomo Chen and the rest of the team in the Cognitive Control lab for a great rotation experience!


Below you will see some PSTH plots for two example neurons from a Neuropixels probe dataset. Using the cue onset and the monkey’s saccade response as the events of interest, the firing rates for the first neuron suggest its involvement in planning the saccade whereas the firing rates for the second neuron suggest its involvement in both encoding visual information and saccade planning.

Prospective Trials.png
Prospective Trials.png
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