That's fascinating. I've fooled around with coupled oscillators, using 555 timers, and seen how little coupling is needed to get synchronization. And that you can synchronize at 2:1 or other ratios, although not as easily as 1:1.
The new idea here is that you can have coupled oscillators running at very different frequencies, and only the ones that are close in frequency will couple. So it's sort of like frequency-division multiplexing, or radio. In a radio receiver, there's only one time-varying voltage coming in, but in that one number is the entire spectrum. So this offers the possibility of connecting some large number of elements without a large number of interconnects.
It takes a lot of cycles to do anything with phase locked systems. Maybe. There are efficient modulation strategies.
It's a new way to think about analog computing. Not clear if it's better.
If biological brains were doing this, researchers should be seeing far more high-frequency activity than is actually observed. There's speculation that something in biological neurons ought to be going fast, because brains seem to get more done than ought to be possible with such slow signals. So far, nobody has found that.
EEG measurements, even at the single neuron level, seem to be below 30 Hz.
There was an article on HN a few weeks ago with speculation that something optical was going on. But it was just speculation.
There are a lot of high frequency electrical patterns in the brain. Individual neurons have a max frequency of less than 200hz (most less than 100hz), but volleys of neural populations can phase lock to much higher frequencies. The hair cells in the ear phase lock to sounds up to 8000hz— this is followed by phase locking in the auditory nerve and further has been followed all the way to cortical synchronization. In humans only measured up to 1200hz in cortex with EEG, but this seems to be a measurement challenge. High frequency neuroscience has a big measurement challenge, actually. Very expensive.
If you are interested in topics like coupled oscillators, synchrony and entrainment, I cowrote a paper that you may enjoy. We cite the OP (2020).
In the retina I believe it is chemicals that selectively resonate to different optical wavelengths. Those then trigger the action potential. (Actually, it’s in reverse, iir— darkness is maximal firing rate and light inhibits the rate of firing). I’ll look it up later and post back.
Note that in the ear, the basilar membrane also affects sound perception, based on selective resonance effects, ensuring that a specific band of hair cells are most likely to phase lock to the sounds. There is both space encoding (ie where on the basilar membrane) and time encoding (phase locking to the signal).
I can confirm that all of this checks out except for the chemical "resonance" in the cones in the retina. It is fascinatingly complex how the molecules are tuned to selectively absorb energy in particular bands of the visible spectrum. Whether one would call this resonance or not will hinge on the definition (fwiw, the definition of resonance in physics can be exceedingly broad).
yeah, if memory serves, the 2:1 coupling is how the parametron mentioned in the article works; given a reference frequency signal such as 6 gigahertz and some oscillators that can oscillate around 3 gigahertz, you have two possible frequency-locked phases that can serve as 1 and 0. one of the half-frequency oscillators serves as a phase reference for the 1 level and everything else is measured relative to it
hmm, now i see that the article explains this, but i guess i'll leave this here as a simplified summary in case that it's useful to somebody
The new idea here is that you can have coupled oscillators running at very different frequencies, and only the ones that are close in frequency will couple. So it's sort of like frequency-division multiplexing, or radio. In a radio receiver, there's only one time-varying voltage coming in, but in that one number is the entire spectrum. So this offers the possibility of connecting some large number of elements without a large number of interconnects.
It takes a lot of cycles to do anything with phase locked systems. Maybe. There are efficient modulation strategies.
It's a new way to think about analog computing. Not clear if it's better.
If biological brains were doing this, researchers should be seeing far more high-frequency activity than is actually observed. There's speculation that something in biological neurons ought to be going fast, because brains seem to get more done than ought to be possible with such slow signals. So far, nobody has found that. EEG measurements, even at the single neuron level, seem to be below 30 Hz. There was an article on HN a few weeks ago with speculation that something optical was going on. But it was just speculation.