[ml] [Noisebridge-discuss] Technical question: Directionally sensitive photosensors

[John Hurliman]

It sounds like you are implementing some form of the Rall cable equation (
http://www.scholarpedia.org/article/Rall_model) to model signal decay? I
don't have any code off-hand, but both of the neuroscience Coursera classes
I'm taking right now (https://class.coursera.org/bluebrain-001 and
https://class.coursera.org/compneuro-001) covered this. Particularly, the
video "Dendritic computation" (
https://class.coursera.org/bluebrain-001/lecture/115). I'm not sure if the
videos are accessible unless you enroll in the class though.

You might try posting to the openworm-discuss mailing list, since many of
the devs there have been experimenting with a variety of neuron simulators
and might be able to point you to some working code.



On Tue, Jun 11, 2013 at 9:34 AM, Mike Schachter
<mschachter at eigenminds.com>wrote:

> Also cc'ing this discussion to the neuro and ML lists, there are might be
> people there that could help with the problem.
>
>  mike
>
>
>
> On Tue, Jun 11, 2013 at 9:25 AM, Mike Schachter <mschachter at eigenminds.com
> > wrote:
>
>> 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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