Researchers have come a step closer to gaining complete control over a mind, even if that mind is smaller than a grain of sand. A team at Harvard University has built a computerized system to manipulate worms—making them start and stop, giving them the sensation of being touched, and even prompting them to lay eggs—­by stimulating their neurons individually with laser light, all while the worms are swimming freely in a petri dish. The technology may help neuroscientists for the first time gain a complete understanding of the workings of an animal’s nervous system.

The worm in question, Caenorhabditis elegans, is one of the most extensively studied organisms in biology: investigators have completely mapped and classified its cells, including its 302 neurons and the 5,000 or so connections among them. But science still does not know exactly “how neurons work together in a network,” says Andrew Leifer, a graduate student in biophysics at Harvard. For example, how does the worm coordinate its 100 or so muscles to relax and contract in a wave pattern as it swims?

To find out, Leifer and his collaborators genetically engineered the one-millimeter-long nematode worm to make particular cells in its body sensitive to light, a technique developed in recent years called optogenetics. Because the worm’s body is transparent, sharply focused lasers, pointed with an accuracy of 30 microns, could turn on or suppress individual neurons with no need for electrodes or other invasive methods. Leifer placed a microscope on a custom-built stage to track the worm as it swam around in a d­ish. He also wrote software that analyzed the microscope’s images to locate the target neurons, then pointed and fired the lasers accordingly. The journal Nature Methods published the results on its Web site (Scientific American is part of Nature Publishing Group).

Other teams have used optogenetics to control individual neurons on immobilized worms. But to understand the organism’s physiology, Leifer says, it is necessary to manipulate it as it swims freely. He and his co-workers were able to show, for example, that during swimming, motor signals move down the body through muscle cells themselves as well as through nerve connections.

Leifer thinks the technique could someday help scientists create complete simulations of the organism’s behavior. “We hope to be able to make a computational model of the entire nervous system,” he says. In a way, that would be like “uploading a mind,” though a rudimentary one.

This article was originally published with the title The Smallest Mind.

4 Comments

1. 1. jtdwyer 10:24 AM 3/17/11

   I think this worm's computational model of its own simple behavior hardly constitutes a contemplative mind and its retained memories. Personally, I have no use for a worm's perspective on the universe, uploaded to some PDA.
   
   Of course, these researchers may have a more ambitious long term objective in mind. Anyone who attempts such nonsense should first upload their own 'mind' and then restore...

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2. 2. scientific earthling 12:07 AM 3/18/11

   A good protein source for future generations as food runs out. All nematodes should be considered of course.
   
   Remember trying to grow round worms that would clump together when disturbed, in my backyard for my tropical fish - not much success. They might make nice hamburgers.

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3. 3. indeseo 05:42 PM 3/21/11

   intelligent comments would be so much more interesting to find here -
   and even tho' this magazine is for the 'amateur', it doesn't seem the place for such accomplished snarkasm - it seems insincere, and it is out of place - try "the comedy club" for those remarks - you might win free drinks!
   Or- donate your own small mind to the scientists for experimentation, and consider your sacrifice to finally be something worthwhile that you have done
   
   "-the contemplative mind-"? as opposed to the contemptual mind?

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4. 4. hoamingin 07:10 AM 3/24/11

   I can see that this is relevant to humans. After all, even the simplest nervous systems and brains have to use the same mechanism, to store a record of a set of conditions which, when recognised, produces an automatic response.
   
   From the time of early multi celled organisms this mechanism had to operate for two functions: one internal signals to coordinate actions of all parts of the body, and the other sensing external conditions to produce appropriate interactions with those conditions.
   
   The large brain gave humans the capacity to store a larger number of scenarios to give finely nuanced responses to a wide range of activities in a hunter gatherer lifestyle. Apart from capacity, the main difference is that, instead of acquiring behaviours as inherited instincts, humans acquire them by learning.
   
   So study of these worms can give us insights into the operation of the brain, but the question I have is whether there is too much focus on the internal coordination function and too little on how worm brains process interactions with external conditions.

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