[Noisebridge-discuss] Technical question: Directionally sensitive photosensors

[Mike Schachter]

I suppose the basic idea is to create a chain of integrate-and-fire neurons.

Referring to the attached diagram, each neuron gets input from it's own
photosensor, and from the neuron to the left of it. You will also have to
make it so that the signal from the photosensor to neuron *decreases* as
you move right on the chain.

The general idea is that movement to the right makes each neuron spike,
which sends a spike to the neighboring neuron. If the inputs are timed
right (which is probably the most tricky part), each successive neuron will
spike more and send more input to it's neighbors. The last neuron, the
readout neuron, will spike the most. You can look at the spike rate of the
last neuron, and if it's high enough, then you declare movement to the
right. The number of spikes of the last neuron could even be related to the
velocity of the movement.

Movement to the left shouldn't elicit a single spike from the readout
neuron.

Another option might be to build a Reichardt correlator:

http://people.csail.mit.edu/rondror/Ronfiles/Research/reichardt.htm

mike



On Mon, Jun 10, 2013 at 11:46 PM, Christoph Maier <
cm.hardware.software.elsewhere at gmail.com> wrote:

> On Mon, Jun 10, 2013 at 5:49 PM, Mike Schachter
> <mschachter at eigenminds.com> wrote:
> > Oh ok! Well I'd be happy to help Chris with code to do
> directional-selection
> > given data from an array of photo-sensitive inputs if that would be
> useful.
> >
> >  mike
> >
> >
> >
> > On Mon, Jun 10, 2013 at 5:20 PM, Norman <pryankster at gmail.com> wrote:
> >>
> >> Mike, that is exactly how a phased array works.
> >>
> >> Norman
> >>
> >>
> >> On 6/10/2013 5:07 PM, Mike Schachter wrote:
> >>
> >> Can you just get an array of non-directional photosensors and do the
> >> direction-selectivity computationally on an arduino or something?
> >>
> >>  mike
>
> Great!
> Just tell me how to put code into this kind of computer ...
> http://pony.noisebridge.net/~cmaier/neuromorphic/BIL2011/html/img10.html
>
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