"Many people would pooh-pooh the notion of insects having brains that are in any way comparable to those of primates," Strausfeld adds. "But one has to think of the principles underlying how you put a brain together, and those principles are likely to be universal."
The findings are controversial. "The evidence that I've seen so far has not convinced me," says Gilles Laurent, a neuroscientist at Caltech. But some researchers are considering possibilities that would shock most lay observers. "We have literally no idea at what level of brain complexity consciousness stops," says Christof Koch, another Caltech neuroscientist. "Most people say, 'For heaven's sake, a bug isn't conscious.' But how do we know? We're not sure anymore. I don't kill bugs needlessly anymore."
Heinrich Reichert of the University of Basel in Switzerland has become more and more interested in "the relatedness of all brains."
"Attention," says van Swinderen, "is a whole-brain phenomenon. A thing is not purely visual, not purely olfactory. It's a binding together of different parts that for us signify one thing. Why couldn't the fly's mechanism [of attention] be directed to a succession of its memories?" he asks. "That, to me, is just a short hop, skip, and a jump away from what might be consciousness." The difference between the memories of a fly and a human might be a matter of degree. The human can store a lot more memories and can therefore maintain a more sophisticated personal narrative of his past and present. But van Swinderen believes "it could be exactly the same mechanism in a fly and a human." Although there is still no evidence to decide either way, the result could be consciousness.
"Probably what consciousness requires," says Koch of Caltech, "is a sufficiently complicated system with massive feedback. Insects have that. If you look at the mushroom bodies, they're massively parallel and have feedback."
Chemical clues confirm that at least some fundamental brain processes are the same in humans and insects. Van Swinderen and Rozi Andretic, a neuroscientist at NSI, have found that mutant flies producing too little of the neurotransmitter dopamine have impaired salience responses. Feeding the mutant flies methamphetamine—a chemical related to drugs used to treat attention-deficit/hyperactivity disorder—relieves the dopamine shortage and normalizes the flies' attention. But give meth to a normal fly and it cannot attend as well. "Similar mechanisms are present in vertebrates and flies," Andretic told me.
When you consider that neurons themselves are strikingly similar across the animal kingdom, it all begins to make sense. "You have the same basic building blocks for vertebrates and invertebrates," says Strausfeld, "and there are certain ways you can put these building blocks together [into brains]." So when it came to building a brain center like the hippocampus that can recognize places, there might have been only one way to wire those quirky neurons together to do the job—and evolution arrived at that same solution multiple times independently, just as the genetic instructions for wings evolved multiple times in distinct lineages.
Monday, April 19, 2010
Research on Insect Consciousness
An old blog post on the blog "Intelligent Life is All Around Us" drew my attention to a fascinating Discover Magazine article, "Consciousness in a Cockroach." I've included some quotations from that piece below. I wonder: What are the best ways to support further research like this?