about
Twitter / X = @vikram0285
Recording and perturbing neural/molecular activity as flies interact with different substrate options and make decisions (e.g., lay eggs) (Vijayan et. al. 2023).
I’m a postdoctoral researcher interested in the biological mechanisms that control the timing and outcome of individual behavioral decisions. My work ranges from exploring neural circuits in the brain to investigating subcellular processes within the body. I work with flies — a highly tractable model organism — with the goal of generating insight that also applies to other organisms.
My most recent publications explore the discrete decision to lay an individual egg with the aim of making headway into the neural mechanisms of cognitive decision making. I noticed that flies search from many seconds to minutes before depositing each egg, and I discovered that flies, remarkably, use a working memory of past egg-laying substrate options to assess the relative value of the current option (Vijayan et. al. 2022). I then developed a head-fixed preparation for recording neural activity (two-photon imaging and electrophysiology) as flies explore substrate options and lay eggs, and I discovered a neural activity signal in specific neurons that fluctuates up and down – over many seconds to minutes – as a fly searches for an egg-laying site. The fluctuations in this signal likely represent the moment-to-moment “considerations” of the fly. The overall propensity of this signal to rise is related to the relative value of the current option and when this signal hits a threshold level, an egg is deposited (Vijayan et. al. 2023, recorded talk). This rise-to-threshold signal helps extend those previously found in mammals by demonstrating that rising processes can causally initiate action and guide minute-timescale or self-paced deliberations between options (not just seconds-timescale or cued decisions). My work raises the possibility that a similar type of signal may exist in humans choosing a dish at a restaurant, for example.
Holistic and dynamic approach to understanding decisions (fly modified from Kim et. al. 2021).
What next? I plan to leverage the advances from my postdoc (both results and setups) to develop a comprehensive, molecular- to circuit-level understanding of the timing and outcome of decisions. While my published work focuses on how real-time signals in the brain guide decision-making behavior, my current/future work will expand to even newer territory by also incorporating real-time measurements in the body (e.g., hormone release) during behavior. This direction emerges from my most recent unpublished results (interactions between the brain and endocrine systems regulating the moments of action) and unpublished preparations (a new preparation to measure neural/molecular signals in the body during behavior). By interfacing the genetic tools and connectomes available in flies, with real-time measurements/perturbations in the brain and body during behavior, my lab will have access to the relevant variables to provide mechanistic explanations for individual behavioral decisions.
The brain (tiny white structure to left) in comparison to other internal organs (single fly, gray = dapi, cyan = phalloidin).
Specifically, my lab will be poised to make comprehensive insight into questions like: (1) Why exactly is an egg laid at time t and not t + T? That is, can we explain each of the up & down fluctuations in the rise-to-threshold signal to understand the mechanisms behind critical phenomena for decision making like internal representations of options, recurrent circuits, spontaneity, body needs, and social influences; (2) How do the brain and endocrine system interact to control the timing and outcome of decisions?; and (3) What are other decision-making signals and principles? Answering these basic questions in the fly may help us understand the principles of behavior generation in larger brained animals like ourselves. I’m currently working at The Rockefeller University in the Laboratory of Integrative Brain Function (Gaby Maimon). I am currently on the faculty job market, please contact me if you have any openings! Contact me at vikram.vijayan@gmail.com or on Twitter / X (@vikram0285).
