Genes And The Brain

Seth - Well I think there are rally two exciting things to think about. The first is this: how do all of those genes that are in all of our DNA (that's about 20 000 of them), how do they make our fantastically complicated brain? And just because we now have the whole of the human genome sequence, we can now start to answer that question. We really don't know at the moment. The other thing that really baffles a lot of people is what genes do in behaviour? People like to think that there's a gene for this and a gene for that, but what we're now finding is that there isn't really any such thing. It turns out that there's actually a whole set of genes, and what we can now say is 'what do all those genes have in common?' This makes us look at the different parts of the brain that might underlie these sorts of behaviours. That's one of the most interesting things now.

Chris - What experiments have you done to try and track down some of the genes that are involved in this?

Seth - Well the members in my group have been trying to find out the molecular basis of learning and memory. One of the amazing things that we've discovered is that a heck of a lot of the genes that are important for learning and childhood learning disabilities all make proteins that are part of a single machine. In the same way that you think of a motor car being made up of wheels and all sorts of bits and pieces, all different sorts of genes are all built together into this thing which is like a molecular automobile in your brain which allows you to learn.

Chris - Have you found any genes that are particularly interesting?

Seth - Oh gosh, lots of them! It's really a very exciting thing at the moment, and we're discovering lots more genes. As part of a big programme we have called the Genes to Cognition Programme at the Sanger Institute, we're systematically studying these genes. With clinical colleagues we're examining humans, and with other experiments in mice we understand the basic mechanisms. One gene we studies recently is very important in learning in boys with a form of a very specific learning disability. It turns out that mice with the same gene mutation also have the same learning disability.

Chris - It's interesting that a very different animal has exactly the same deficiency as a human. Presumably animals can teach us a lot about how our own brain works because of exactly this kind of work.

Seth - Yes indeed. There's a lot we can learn by studying animals. But let me bring up something that we've been looking at lately, which is the evolution of behaviour and where does it all come from. I can tell you that one of the new approaches to this is to say that as we've found all these genes important to learning in a mouse and in a human, we can look at when they first evolved. It turns out that some of the genes that are involved in human learning actually evolved before humans evolved themselves. They arose when they were single celled animals. Single celled animals then evolved to become these multi-cellular worms and then flies and other things. And as evolution progressed, we actually developed some new genes that evolved with learning. So some learning genes are very very ancient, while some a very recent.

Chris - It's also interesting to note that everyone in this room shares 60% of their genes with a banana, which Steve Jones was kind enough to tell me when I interviewed him a while back.