XLANDC

My neurons work well enough (99% of the time), doing what I wanted from the beginning, yet I still see no complex correlations. Why ? Because theoretically is not possible to have such a random input and get order from there… I have tested multiple hypothesis, frequency , phase surface distribution, different leakage with distance, multiple models for inhibition… Nothing lead me to believe that they could work.. Synapses break because the input is too different from “receptor” to “receptor”.. So I have come to the conclusion that the input must be structured somehow … Meaning some receptor fields have to respond the same, regardless of the particular wavelength, brightness, direction, they receive… Maybe respond with an average response, min, max… does not matter, but it has to be the same.. Also is not possible to have large differences in latency among close receptors and then neurons.. The latency it’s a compounded variable that contains data about frequency, wavelength and direction. If the resulting latency is bigger than the time it take for a neuron to fire, that synapse has no contribution to the activation of that neuron so it should be removed.. But such large latency is the norm in my system.. This also has to stop..

But what kind of structure should I aim for ? Not sure at all…

I have my very first logic rule: If A > B then A =1 and B =1, if B>A then A=0 and B =1. I’m not sure what to make of it. More important I cannot find any reason for why A is bigger than B in the first place, what creates this initial asymmetry.. To reach that logic end, I need perfect timing and that has proven very difficult.. Even a cycle off and the whole network loses coherence. I’m not sure what to make of this particular problem .. Is our brain so precise ? It could be because in the end, the computation is done by the electrostatic potential which is the definition of precision… But I’m not convinced, if there are correction mechanisms, what are they ? So I need inhibition to hit at a very precise time in all layers in all cycles and it doesn’t. On the other hand why do I have this imprecision ? When adding all synapses I get a value that is not precisely the activation potential (AP), is slightly higher, when trying to redistribute that error on all synapses I fail to account for their precise contribution. Everything I tried, failed, so the system works 99.9% as expected, but that is not enough. I still get cascade failure where all neurons get stuck in a dying state.

Anyway, the progress is very very slow, so now I’m not sure any more that I’ll have some significant progress by the end of the year 🙁

I tried everything I could think of. Once in the neural net, I could not find a way to control frequency. I cannot add, subtract, average, min, max different frequencies. So I’m abandoning this thread for now. I’m still not 100% convinced, but maybe I will never be 100% convinced of anything. The neuron can work withing a broad range of frequencies, but cannot work with synapses running at different frequencies. Perhaps horizontal / amacrine / bipolar cells together work to eliminate completely the multiple frequencies generated by the receptor cells and average to a single frequency per frame… I thought they only minimize frequency difference among different regions but maybe they go all the way and eliminate it entirely. Could be possible.

So once again, I’ll consider only latency.

To summarize : I made no progress 🙁

In the demo below, some things are choreographed (as in they are not entirely what they seem to be):

• Colors are fake, they are converted to shades of gray, to get “true” color neurons specific for RGB are needed
• Background was removed due to some unspecific interference. It should have worked and works for the majority of patterns but not for all. I’m not sure where the error is coming from.
• While position seems 100% invariant, it is not. To get direction, I programmed receptive fields like areas. This results in a heterogeneous pixel output, so I drew the lines on the upper and left side of a receptive fields, but this is not seen in the displayed image. To get to true invariance an additional level of abstraction is needed .
• The image is a 70 x 70 pixel, but since each receptive field is a 7×7 area, what it seen nowappears as a 10×10 pixel image.

I’ve made progress with the LTP/D algorithm, seems perfect now. I ran into problems with the Inhibitory neuron.. I’m not sure what is supposed to accomplished. I ran into problems with the dynamic synaptic connection, so in this video I have full connect.

As predicted at the beginning of 2023, I did not make any significant progress in 2023 :(. It did not seem feasible but I was still hoping . So what did I do in 2023 ?

1. I found a feasible mechanism for learning, but since learning is not a single step process, would be better to rephrase and say that I only have a step of the process of learning, however I consider that to be a significant step. That would have been significant progress if I could test it properly. Identifying 2 inputs in a simplistic set up is not even proof enough that the theory works, yet I still think it does.
2. I now have a theory for what should LTP/D accomplish. I spent more then 3 months only on this, but I’m nowhere close to proving it as being good or bad. As far as I can tell, this is a must, because high frequency and multiple synapses are making the output unreliable.

So in terms of algorithms, that’s it… Does not seem much, the year has gone by very fast it seems. In terms of programming I made more progress, but programming it’s an empty shell. I moved to cython and dearpygui and also created an additional GUI interface to work with very few neurons, but in a more easy to understand way.

What’s the plan for 2024 ?

I need to clarify LTP/D.. IF I can do this, then I can do many more interesting things, even have significant progress.. Yup… I think this year is possible to have significant progress… But I will not do anything else till I have this done. I gave up on all the other possible approaches.. no more programming, no more network. Only a single neuron with different number of inputs and different frequencies..

there are cases where the pre-synaptic neuron, fires twice before the postsynaptic fires once…. There are at least 3 cases to be discussed but the main question is why should this be an acceptable behavior ? This leads to cases where the time between activation of pre and post synaptic neuron is relatively big… I believe LTP (long term potentiation) is meant to to deal with precisely this case.. Then we have the opposite … summation of thousands of synapses … this should be where LTD comes to help.. I’ve done all the simulations I can with current model and the preliminary conclusion is that the synapse is in fact undecided …. I could not find any scenario where the result is certain.. If input varies wildly all variables of a synapse (4 in total) change the synapse from “increased strength” to ” decreased strength ” and vice versa … I understood that a biological neuron cannot have in infinite number of synapses… but certainly a digital one, would not be bound by such non-sense limitations … Not true… with current variables, my model is limited to about 80 synapses per neuron … this number is somewhat arbitrary, but there is no theoretical option that this number could be infinity… The time summation is not an option either… if neuron cannot adjust (because the presynaptic fires too frequent) so we have one to one, pre and post -synaptic firing relation ship, that synapse breaks … which is observed both in biology and in my simulations… So I’m left with no good options… I need to find a balance and to limit accordingly the input values … but so far I failed … I was convinced that I could find a definite solution ..

Running actual images where the background is a thing put all my theories on ice.. I first realized that when I have many synapses for a neuron and few for another, it modifies the activation phase …d’ooohh… and I had to bring back my old nemesis, frequency. Frequency means now that a neuron can receive multiple pre-synaptic inputs before it fires once. I discarded this idea not only because it complicates matter, but I though this should not be the default mechanism, because would be a waste of energy.. Besides with thousands of synapses is not very likely for a neuron to wait for a secondary activation to do a time summation for activation. Anyway, I thought by bringing frequency back, the very bright neuron would win the inhibition battle.. Not likely, multiple synapses would still win. The consequence is that the background is selected instead of the foreground.. because it’s big 🙂 . How are CNNs dealing with this issue ? I’ll have to look into it. I have thought long and hard… I see no way around this, because in a way is the expected behavior given my algorithms… But, as with many other problems, I have a general solution.. I’m going to ignore it… I’ll chose a very low intensity background, I’ll avoid using both ON and OFF bipolar cells from the receptive fields and go with this. Sure I can’t have real images now, but maybe along the way I’ll find a solution or a solution would present itself..

I coded some parts of the retina circuitry, now I have receptive fields, but still no color vision. Receptive fields are not as selective as they could be, but should be enough for now. Images are transformed to gray because I found no easy way to add in RGB data.

I also did some simulations to understand CA1 region but I still see no point in that complex arrangement. I did find something useful, a way to reduce phase difference. My focus was to get as much phase difference as I could, but then I realized that I also need to reduce the phase difference, somehow. So after 4 layers, with current set up, I get the same phase.

Anyway I one again got stuck in dealing with frequency. Different frequencies start from the receptor, eventually break synapses and I found no way to have a single frequency at time t for all regions from the visual field.. Unless I impose a single unchanging frequency. As far as I can tell frequencies play an important role so there should be a way to let them in. It seems the amacrine cells correlate frequencies for the bipolar cells they modulate, but I could not find this to be true in literature. There is very little information regarding amacrine cells.

A way to receive data, a way to discriminate data, a way to store and retrieve, a criteria to select what should be stored for later retrial.

From all of the above steps as far as I can tell I only have the discrimination algorithms, which in fact depends on the received data and on the selection of what should be stored algorithms. So it’s incomplete or it lacks complete parametrizations.

I worked on data receiver, converting visual data (RGB pixel values) into data that can be accepted by the discrimination algorithm. For color discrimination just converting a number into a different number through some function is enough. But to detect lines of different inclinations, colors, dimensions.. that is not enough.. So I started implementing the “receptive fields” concepts from retina, with the ON and OFF behavior and center/surround. I have yet to find relevant details for implementation. So I guess is trial and error again. For example I have found no details of the size of the center vs surround. Small center, makes it hard for light to hit it, to hit only the center and not the surround, so ON centers are darker than expected and OFF center brighter… But this results in good discrimination for line inclination .. There are also contradictory information about horizontal cells .

I have looked at a way to store data, CA1 region from the hippocampal circuit seems interesting because of its configuration. But even the simplest simulation shows that a neuron cannot link back into itself… But maybe I’m missing something. Anyway that seemed like an interesting way to discriminate small similar patterns.

Data retrieval remains mysterious, it seems we retrieve data by recreating it in an altered version.

How to select data to be stored ? This is an area for which I have no idea… But for now this can be bypassed the easiest.. I tell the system when to store that data. The system stores automatically data that passes some abstract threshold, but there are trade offs with this approach, so in fact most of the data does not reach that threshold.

Anyway, “learning” remains open for debate.

My progress has been slow, there are things that I can do and I know how to do, but I lack motivation to do them because they don’t seem important. And then there is an infinite list of mostly poorly defined tasks.