pawan sinha is so is yacht professor in neuroscience at m.i. tinchts where he leads the lab. he has done amazing work in india as a part of a project for children who suffered injury or disease to the eye. in answering these questions, once again my cohost, my guide, my professor is dr. eric kandel. he is as you know from our program a noted brain sign test. he's a noble laureate. he's affiliated with columbia, the howard hughes ion substitute has written a remarkable book about the search for memory and he is for this program a great friend. so i am pleased to have his wisdom and his direction guiding us as we try to learn more in this multipart series about the brain. welcome again. >> thank you charlie, always a pleasure to be here. >> charlie: we look at the introduction in our first episode. tonight you've chosen visual perception. why do we start there. >> we chose this together, charlie. we chose it because we understand the visual system better than any other system of the brain and because it is a model for how the brain wor. if we understand how vision works in the