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Gap-free neural circuits
Dec 8, 2012, 11:38a - Science

As I mentioned in a previous post, Tots and I are teaching a class on neural circuits this January during IAP at MIT. IAP is a time where anyone can teach anything they want - I think it's a cool testing ground for classes, and we didn't have anything like it that I remember at Stanford.

I'm excited about teaching this class because I see a significant void in the neuroscience classes taught at MIT, and perhaps in neuroscience research in general. Science has gotten very good at molecular and electrical manipulations over the past 50 years, and we're also very good at observing macroscopic phenomena like exhibitions of memory and behavior. Linking the two in a coherent way is what's missing. We can easily tell you that a mutation in a gene called CREB causes a significant learning and memory defect in mice, but it's much more difficult to tell you how CREB does this. We might be able to tell you that CREB acts in neurons, or even in a specific type of pyramidal neuron in a specific place in the brain, the hippocampus. We probably can even tell you that CREB functions as a transcription factor to "turn on" a bunch of other genes which are important for keeping a memory. But how exactly these gene products connect with the specific act of remembering remains cryptic, and I suspect it will stay that way for a very long time, because there are so many neurons in the mouse's hippocampus, and its functional inputs and outputs are unknown.

How can we understand what a neural circuit does if we don't even know the form of its input? It's like programming a function to do something without knowing the data structure you're going to be getting - it's a futile effort.

There is a huge gap between our understanding of biochemical molecular function and the phenomena that these molecules function in. It's incredibly difficult to bridge this gap in mammals, because there are billions of neurons and their physical accessibility (buried beneath inches of other neurons) and identification is extremely difficult. Simpler organisms, like microscopic worms, fruit flies, and other invertebrates, have fewer neurons that are more accessible: for example, the microscopic worm C. elegans is transparent, and under a microscopic you can see every cell, and every cell and neuron has a unique name.

In invertebrates, there's a chance for "gap-free" circuit analysis: we can bridge the gap between the molecular function of a gene and its function in determining a behavior. Several papers discuss these "gap-free" circuits, and we're going to cover them in our class.

There are virtually no classes on "gap-free" circuits at MIT, so we're taking a stab at one. I've never taught a class before, so we'll see how it goes.

Tots and I finished making the class website yesterday, so take a look! We've sorted out the syllabus, so the details and the readings are there. I'm excited about this...

Read comments (1) - Comment

neha - Dec 8, 2012, 11:38a
this is awesome nikhil. i might stop by the first class!

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