Sean Mackesey

Reveal Contact Info

PhD Student


Sommer Lab

Current Research

Episodic memory functions optimally when it provides information most relevant to the present context. One type of information likely to be relevant is any that was previously stored within the same context. Human episodic memory reflects this principle across varying timescales– we remember childhood moments when we return to our childhood homes, and we remember that unusually bold squirrel we passed on our walk to work on Tuesday when we pass the same spot on Thursday. The brain region likely central to this function is the hippocampus, which is implicated in both navigation and memory. Damage to the hippocampus causes severe impairment of episodic memory, and individual hippocampal neurons code the location of animals as they navigate an environment. My research is focused on exploring the connection between memory and navigation by exploring codes embedded in hippocampal field potentials. The advent of high-density recording arrays has led to the increasing availability of high-dimensional field potential datasets in hippocampus. I apply unsupervised learning and other statistical techniques to these datasets in order to reveal information about stimulus and behavior encoded in the field potential signal. Recently, I have also begun to branch out by applying similar methods in calcium imaging datasets from zebrafish. I also take an interest in neuroinformatics and was involved in the early development of the Neurodata Without Borders Neurophysiology format.


I hail from a den of lobbyists, defense contractors, and bureaucrats: the wooded suburbs of Northern Virginia. After a pleasant suburban childhood, I spent my undergraduate career (Northwestern U) reading random books and doing a chemistry major. I was never very passionate about chemistry: my greatest achievement was taking a sulfuric-acid-induced trip to the chemical shower. Sometime during my post-college years as an ESL teacher in Poland and South Korea, I became fascinated with one implication of the materialist theory of mind — if all of our experiences have physical correlates in the brain, then there must be an experience-space in some sense “isomorphic” to the space of possible brain architectures… Who knew that our place in mind-space is just like our place in the physical space! A tiny island in a vast ocean of possibility. Unfortunately, the currently available means to take vacations from our little corner of mind-space are limited to meditation, drugs, sleep deprivation, and head trauma. I decided to pursue computational neuroscience because it seemed like the best way to contribute to the development of alternatives. After a stint learning programming and helping build a knowledge base out of 100 years of hippocampus literature (, out of the Ascoli Lab at George Mason University), I ended up at the Redwood Center. These days I study hippocampal neural codes in Fritz Sommer’s lab and read political theory in my spare time.