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ref: Brown-2007.09 tags: motor force field learning vision date: 02-20-2009 00:28 gmt revision:1 [0] [head]

PMID-17855611 Motor Force Field Learning Influences Visual Processing of Target Motion

  • as you can see from the title - this is an interesting result.
  • learning to compensate for forces applied to the hand influenced how participants predicted target motion for interception.
  • subjects were trained on a robotic manipulandum that applied different force fields; they had to use the manipulandum to hit a accelerating target.
  • There were 3 force feilds: rightward, leftward, and null. Target accelerated left to right. Subjects with the rightward force field hit more targets than the null, and these more targets than the leftward force field. Hence motor knowledge of the environment (associated accelerations, as if there were wind or water current...) influenced how motion was perceived and acted upon.
    • perhaps there is a simple explanation for this (rather than their evolutionary information-sharing hypothesis): there exists a network that serves to convert visual-spatial coordinates into motor plans, and later muscle activations. The presence of a force field initially only affects the motor/muscle control parts of the ctx, but as training continues, the changes are propagated earlier into the system - to the visual system (or at least the visual-planning system). But this is a complicated system, and it's hard to predict how and where adaptation occurs.

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ref: notes-0 tags: spike patterns neural response LGN spike_timing Sejnowski vision date: 0-0-2006 0:0 revision:0 [head]

http://www.jneurosci.org/cgi/reprint/24/12/2989.pdf

  • quote: " when a cortical neuron is repeatedly injected with the same fluctuating current stimulus, the timing of the spikes is highly precise from trial to trial and the spike pattern appears to be unique"
    • though: I'd imagine that somebody has characterized the actual transfer function of this.
  • mais: we conclude that the prestimulus history of a neuron may influence the precise timing of the spikes in repsonse to a stimulus over a wide range of time scales.
  • in vivo, it is hard to find patterns because neurons may jump between paterns & there is a large ammount of neuronal noise in there too. or there may be neural "attractors".
  • they observed long-term (seconds) firing patterns in cat LGN (interesting)

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ref: notes-0 tags: praxis movement vision date: 0-0-2006 0:0 revision:0 [head]

  • praxis is the ability to plan and sequence unfamiliar actions.
  • things are only remembered when they produce motor output.
  • if you put an eye patch over one eye in a 2-year old human for two weeks, the child's vision in that eye will be permanently impared.
  • movement stimulates creativity.