Aravinthan Samuel, Ph.D.

Associate Professor of Physics

Harvard University
Dept. of Physics
60 Oxford Street
Cambridge, MA 02138
Telephone: 617-384-9435
Fax: 617-495-0416
Email: adtsamuel@gmail.com
Lab Website: The Samuel Lab

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 responding to physical sensory inputs. These inputs (e.g., temperature, pressure, electric fields) 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.

References

• Linjiao Luo, Christopher V. Gabel, Heon-Ick Ha, Yun Zhang, and Aravinthan D.T. Samuel (2008), “Olfactory behavior of swimming C. elegans analyzed by measuring motile responses to temporal variations of odorants,” J. Neurophysiol. 99, 2617-2625.
• Christopher V. Gabel, Faustine Antonie, Chiou-Fen Chuang, Aravinthan D. T. Samuel, and Chieh Chang (2008), “Distinct cellular and molecular mechanisms mediate initial axon development and adult-stage axon regeneration in C. elegans”, Development 135, 1129-1136.
• Cynthia A. Chi, Damon A. Clark, Stella Lee, David Biron, Linjiao Luo, Christopher V. Gabel, Jeffrey Brown, Piali Sengupta, and Aravinthan D. T. Samuel (2007), "Temperature and food mediate long-term thermotactic behavioral plasticity by association-independent mechanisms in C. elegans" J. Exp. Biol. 210: 4053-4052.
• Christopher V. Gabel, Harrison Gabel, Dmitri Pavlichin, Albert Kao, Damon A. Clark, and Aravinthan D. T. Samuel (2007) "Neural Circuits Mediate Electrosensory Behavior in Caenorhabditis elegans" J. Neurosci. 27(28): 7586-7596.
• Damon A. Clark, Christopher V. Gabel, Harrison Gabel, and Aravinthan D. T. Samuel (2007) ``Temporal activity patterns in thermosensory neurons of freely moving C. elegans encode spatial thermal gradients'' J. Neurosci. 27(23): 6083-6090.

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