We are working on the theory that memories are stored in the pattern of connections between brain cells. To store memories in this manner, the brain must convert information into activity patterns, modify connections, and stably retain these modifications. Our research covers each of these topics.
First, we use optical imaging to monitor activity in the hippocampus, which receives many kinds of sensory input and is implicated in memory. We analyze the patterns of activity, to better understand coding and representation.
Second, the brain sets up connections between cells depending on input. To work out if two cells are connected, we test if signals from the first cell can affect activity in the second. Building on advances in microscopy, we can monitor single-cell activity using chemical sensors whose light emission changes when a cell is active. Thus, in a section of brain, the brightly lit-up cells represent the ones which have received input. By systematically stimulating different inputs, we can build up small but precise connection diagrams. We anticipate that as these connection diagrams scale up, we will begin to see traces of memory storage in the connection patterns. Details on this resource can be found at the URL: http://www.ncbs.res.in/node/346#MS
Third, the connections need to be stable to store information for a long time. This is very hard to do, because each connection, or synapse, is so small that a relatively small number of individual molecules must do all the work and withstand thermal noise, turnover, and chemical insults. We probe events at these tiny scales using both experiments and computer models. In the computer models we analyze how tiny molecular circuits in each synapse can do computations and can store information reliably. This turns out to be closely coupled to many other cellular processes: the electrical signals in brain cells, physical reshaping of synapses, and synthesis of new proteins. We are developing powerful software tools to model how these events are orchestrated. This software MOOSE <http://moose.ncbs.res.in>, runs from windows laptops to giant Unix-based supercomputers. Details on this resource can be found at the URL: http://www.ncbs.res.in/node/346#SS
Overall, our work falls into the domains of systems biology and computational neuroscience, with a lively mix of experiments and computer modeling. Our lab includes people from physics, chemistry, mathematics, biology, computer science and other branches of engineering.