
Physics Department Faculty:
Aravinthan Samuel
Assistant Professor of PhysicsPhD 1999, Harvard University
Animals are intrinsically computational. We acquire sensory information about our environments, transform this information into neural representations and memories, and calculate and execute decisions based on recent and past experiences. Our own brains are staggeringly complex, with billions of neurons networked by trillions of synapses. But the basic "stuff" of our brains - molecular and cellular structures and interactions - is shared with our simplest animal relatives. Thus simple and well-chosen model organisms can be accessible vantage points with perspective over general biological principles. We study brain and behavior in the roundworm C. elegans. The worm only has 302 neurons, but is capable of a variety of behaviors that display a range of computational powers. We focus specifically on navigational behaviors to physical sensory inputs. Physical sensory inputs can be delivered to the behaving worm both reliably and quantifiably. Navigation itself can be reduced to a quantified pattern as an alternating sequence of forward movements, turns, and reversals. From the systematic analysis of outward motile behavior we can infer the inner workings of neural algorithms. Applying recent advances in microscopy and optics, we are also able to manipulate and monitor the workings of these neural circuits in the intact animal. In this way, we strive to link brain and behavior in the simple but fascinating creature.

- Samuel Chung, Damon Clark, Christopher Gabel, Eric Mazur, Aravinthan Samuel, "The role of the AFD neuron in C. elegans thermotaxis analyzed using femtosecond laser ablation," BMC Neuroscience 7:30 (2006).
- Damon Clark, David Biron, Piali Sengupta, Aravinthan Samuel, "The AFD sensory neurons encode multiple functions underlying thermotactic behavior in Caenorhabditis elegans," J Neurosci. 26:7444-7451 (2006).
- David Biron, Mayumi Shibuya, Christopher Gabel, Sara Wasserman, Damon Clark, Adam Brown, Piali Sengupta, Aravinthan Samuel, "A diacylglycerol kinase modulates long-term thermotactic behavioral plasticity in C. elegans," Nat Neurosci 9:1499-1505 (2006).
- Linjiao Luo, Damon Clark, David Biron, L. Mahadevan, Aravinthan Samuel, "Sensorimotor control during isothermal tracking in C. elegans," J Exp Biol 209:4652-4662 (2006).
- Damon Clark, Christopher Gabel, Timothy Lee, Aravinthan Samuel, "Short-term adaptation and temporal processing in the cryophilic response of C. elegans" J Neurophysiol, in press.









