We suggest that the techniques of transcranial electrical stimulation need to be keept into account, along with the amplitude and frequency of the applied waveforms (Reato), and also their scaling slope.
http://arturotozzi.webnode.it/products/trranscranial-stimulation-a-proposal-concerning-the-parameters-of-the-waveform-to-use/
I've read your argumentation. You say: it's not only amplitude and phase, let's use the 'fractal waveform'. Few remarks.
What you call fractal waveform is indeed not a waveform at all. Fractality means that you only imply a certain relation on scaling of power spectrum. It completely disregards the phase. So forget about the harmonic decomposition as it will give you nothing more. Secondly, it could be interesting to move towards models, which exhibit such a scaling: refer e.g. to http://www.scholarpedia.org/article/1/f_noise or https://www.researchgate.net/publication/243220418_1__f_Noise_decomposition_in_random_telegraph_signals_using_the_wavelet_transform
which is interesting as in EEG you also have a summation of many superimposed signals (btw, as far as I rememeber geography of Italy, Palermo is not so far from Napoli ;-) ).
Finally, from the technical point of view, note, that in the 1/f^alpha noise the majority of spectral power is transmitted in lowest frequencies. And the stimulation you apply is most probably much much shorter than the region of scaling of the frequency. So anyway you will cover only a small part of scaling and OK, you may apply some kind of a stochastic process instead of a pure sine.
Cheers
Teodor
http://www.scholarpedia.org/article/1/f_noise
Article Noise decomposition in random telegraph signals using the wa...
Dear Thodor, thanks for your skillful explanation.
I have some remarks. We know that all the frequencies, from alpha to gamma, exhibits a power law spectrum (see the papers by He and Raichle).
An example of my idea: if you apply an external gamma wave to the posterior zone, you entrain the visual cortex. My idea is to apply the gamma wave with two different amplitudes, chosen on two different power slopes. The important thing is that the two waves are along the path of two fractal slopes. If my idea is right, the visual sensation will change from an amplitude to another, given the same gamma frequency.The three problems of the many superimposed signals, of the different frequencies of the waves (alpha, gamma, beta and so on) and of the different phases of the waves are not important, because the posterior cortex will be entrained by our external superimposed gamma.
I think the waveform is defined by the amplitude pattern, the variations of amplitude in time. Stimulation with redundant patterns (as in the case of neural synchrony in theta, alpha, beta, gamma, etc) do not convey information, but can modulate the kind of brain function. As Walter Freeman puts it, these redundant patterns are carrier waves that select which brain system and related function will be activated, but the information content (that he calls "meaning") is given by amplitude modulation.
Dear Arturo. Yes. Transcranial stimulation is effective for the condition assessment of the entire pattern of stimuli. Frequency, amplitude, pulse shape, the slope, the fractal nature of stimulus or aperiodic, duration of stimulus and the whole complex ... Much of this issue has not yet been studied. I am sure that many regularities in the activities of the healthy and diseased brain will be open. If we consider and summarize the above.
The role of my "fractal" external currents is no to give a message to the cortex, rather to activate, modulate and entrain the message already contained in each cortical area. The change in fractal slope in currents, according to my idea, could activate the cortex in a different way, so that the sensation (or each other function o the brain) becomes different when the power-law of the external input is modified.
I too think that the spikes, other than containing the message, synchronize and fasten the brain activity, but it is a matter of dispute...
Concerning the role of the spikes in the neural code, my ideas are expressed here (to whom it may concern!):
https://www.researchgate.net/publication/271204634_THE_NEURAL_CODE_NOT_JUST_SPIKES%21_httparturotozzi.webnode.itproductsthe-neural-code-not-just-spikes-
Preprint THE NEURAL CODE: NOT JUST SPIKES! http://arturotozzi.webnode...
My last paper on J Theoretical Biology: HOW TO TURN AN OSCILLATION IN A PINK ONE
https://www.researchgate.net/publication/275587530_HOW_TO_TURN_AN_OSCILLATION_IN_A_PINK_ONE
Article How to turn an oscillation in a pink one
Actually I'm working with tDCS, another form or electrical stimulation as you know. I know a good paper that maybe could help you to answer your question. This paper suggests that we must see the stimulation in terms of total energy, total charge and charge density, more than time, current, frequency, etc. (the author describes it as secondary variables). The main goal is to control the electrical field into the brain.
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