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A Worm's Mind In a Lego Body

Posted by timothy on from the with-very-few-exceptions-is-not-a-worm dept.

mikejuk writes The nematode worm Caenorhabditis elegans (C. elegans) is tiny and only has 302 neurons. These have been completely mapped, and one of the founders of the OpenWorm project, Timothy Busbice, has taken the connectome and implemented an object oriented neuron program. The neurons communicate by sending UDP packets across the network. The software works with sensors and effectors provided by a simple LEGO robot. The sensors are sampled every 100ms. For example, the sonar sensor on the robot is wired as the worm's nose. If anything comes within 20cm of the 'nose' then UDP packets are sent to the sensory neurons in the network. The motor neurons are wired up to the left and right motors of the robot. It is claimed that the robot behaved in ways that are similar to observed C. elegans. Stimulation of the nose stopped forward motion. Touching the anterior and posterior touch sensors made the robot move forward and back accordingly. Stimulating the food sensor made the robot move forward. The key point is that there was no programming or learning involved to create the behaviors. The connectome of the worm was mapped and implemented as a software system and the behaviors emerge. Is the robot a C. elegans in a different body or is it something quite new? Is it alive? These are questions for philosophers, but it does suggest that the ghost in the machine is just the machine. The important question is does it scale?

4 of 200 comments (clear)

  1. No programming? by tomhath · · Score: 5, Insightful

    The key point is that there was no programming or learning involved to create the behaviors.

    Yes, there was. The behaviors didn't just "emerge", they're coded into the robot.

    1. Re:No programming? by Kjella · · Score: 5, Insightful

      If you call copy-paste programming. They took an "executable", dumped it from the worm's brain, put it in a robot and found it acts like a worm. The behavior emerged through evolution and was encoded in the neurons by nature, not the researchers. If you could dump a human brain, put it in a robot and have it act like a human without ever "reverse engineering" it that would be most impressive.

      --
      Live today, because you never know what tomorrow brings
    2. Re:No programming? by teslar · · Score: 5, Insightful

      The behavior emerged through evolution and was encoded in the neurons by nature

      What has been implemented in this robot has nothing to do with biological neurons of C. elegans.

      The robot uses integrate-and-fire neurons. The "signal" sent from pre- to postsynaptic neuron is an integer equal to the number of connection between the neurons in the real worm. If the sum of input exceeds a threshold, the neuron "fires" (sidenote: right here's a bit of programming: how did the threshold values get chosen?).

      C. elegans neurons do not "fire" (they are not spiking neurons and lack Na+ channels) but use calcium-based analog signals.

      The body does matter too. C elegans has muscles on either side that it contracts alternately to move in a sinusoidal fashion. Not wheels. C elegans locomotion does not work like wheeled locomotion.

      So, yes, you are right, C elegans neurons encode behaviour appropriate for a C elegans body given the biology of the neurons available here. None of this, however, makes it into this robot. An abstraction of the connectome does (C elegans has both electrical and chemical synapses; that distinction seems to be lost here too) and that's it.

      It is kinda cool that the connectome does seem to naturally implement some basic response patterns; but given that muscles have been replaced by wheels, I'm not sure how meaningful that actually is.

    3. Re:No programming? by Tyr07 · · Score: 3, Insightful

      Actually they did just emerge.

      You see, these neurons were wired in the living worm to send signals to different parts of the body. A signal from its nose, in the real worm, would go to a neuron, which would fire other neurons, that caused it to stop moving. This happened by sending a signal to other neurons which then sent them down to parts of the body.

      What they did, was use UDP packets to be the 'signal', and then sent electrical currents down to the robotic corresponding parts as the original living worm did, which resulted in the same behavior.

      They didn't put a chip in where it goes if range 20cm stop. They mimicked the worm and said if range 20cm send signal to neuron C. Neuron C in the worm and robot goes if receive signal, send electrical pulse to wire C. Wire C causes it to stop motion.

      So behaviors emerged, were not "programmed" so to speak.