[Eeglablist] Open online discussion: How Do Cable Theory and AMPA/GABA Balance Compare in Their Contributions to 1/f?

[Ching-Ming Lee]

Thank you all for these profound insights. I find the 'variable RC
circuit' perspective particularly compelling.
>From a biophysical standpoint, if we view the neuron as a dynamic
cable, the opening and closing of ion channels (gating) essentially
represent the real-time modulation of resistance (R) and capacitance
(C). In this framework, the E/I balance is not a competing theory, but
rather the functional driver that dictates these parameter shifts.
Our longitudinal n-of-1 data suggests that while the anatomical
structure sets the 'static' baseline of the cable, interventions like
rTMS trigger a dynamic state-shift in these RC properties. The most
intriguing finding is that this shift isn't infinite; when the
exponent reaches a certain threshold (~1.8 in our case), we observe a
non-linear 'Network Collapse' in global efficiency (via WPLI
analysis).
This implies that the 1/f exponent might be a 'System Health Index'
that tracks how close the neural cable is to its functional
boundaries. It’s a beautiful intersection where cable theory provides
the physical medium, while E/I dynamics provide the regulatory signal.
I would be curious to hear your thoughts on whether this 'Network
Collapse' could be interpreted as the point where the RC parameters
reach a state of functional saturation or over-inhibition.


Евгений Машеров via eeglablist <eeglablist at sccn.ucsd.edu> 於
2026年4月15日週三 下午10:42寫道：
>
> >Hi Ching-Ming, Yevgeny, and Cedric,
>
>  >Thank you for sharing your experience and results!
>
>  >*Structural Stability vs. Dynamic Change:* Since the subject's neuronal
>  morphology (cable theory properties) cannot change by 60% within 3 hours,
>  this massive shift provides strong evidence that *E/I balance
>  (GABA-mediated inhibition)* is the primary driver of 1/f *dynamics*,
>  even if cable theory sets the *baseline*.
>
>  >Cable theory describes that when a neuron receives synaptic inputs at
>  synapses that are located further from the soma, it generates more low-pass
>  filtered post-synaptic potential. See a nice illustration from Rall et al.
>  (1967)
>  https://urldefense.com/v3/__https://github.com/sccn/OneOverF/discussions/8__;!!Mih3wA!DHtN8b_WLfq9LU0kcatC6qilNfGVpUWCoDhdGUr5gz4qcT4adsUlFefUMcDmaZVmsSJ6ai6Kq6mOCrDe05dArQOcMds$
>
>  >Stephanie Jones' human neocortical neurosolver (HNN) has an explicit 2x2x2
>  models: cells at layer 2/3 and 5, distal and proximal inputs, and
>  excitatory (pyramidal neurons) and inhibitory (basket cells) neurons. Among
>  these parameters, 'distal input' is likely to be associated with 'more
>  low-pass filtered post-synaptic membrane potentials'.
>
>  >Ching-Ming, thus the question is 'Can TMS (or any other intervention)
>  change the balance between distal and proximal inputs?' This is much
>  trickier than thinking whether or not neural morphology can change by 60%
>  in 3 hours.
>
> > We can think of synaptic inputs to apical dendrite in superficial layers as
>  a typical case of 'distal input'. If TMS (or any other intervention such as
>  hyperventilation) can increase relative amount of 'distal input', that
>  would shift 1/f to 'steeper' = 'as if GABA_A-R is dominant at the
>  measurement site'.
>
> > What can increase inputs to apical dendrite? I published a paper last year
>  that extralemniscal thalamic (EXLEM) projection goes to the superficial
>  layers (about 25%; See 'type 2' in this illustration
>  https://urldefense.com/v3/__https://github.com/sccn/OneOverF/discussions/17__;!!Mih3wA!DHtN8b_WLfq9LU0kcatC6qilNfGVpUWCoDhdGUr5gz4qcT4adsUlFefUMcDmaZVmsSJ6ai6Kq6mOCrDe05dAARwz5uE$ ). EXLEM is the same as
>  'non-specific thalamus' mentioned by Grey Walter, Robert Galambos etc..
>  Recently, Giandomenico Iannetti has been leading the revival of EXLEM.
>
>
> It's possible that the presence of an effect from transcranial magnetic stimulation doesn't refute the cable theory's explanation of the dependence (although it is extremely interesting information). This is because the RC circuits formed by dendrites, which transform the pulse shape, differ in their properties from those used in radio engineering. Changing resistance or capacitance by applying voltage to a conventional radio engineering resistor or capacitor is impossible (at least until the capacitor breaks down or the resistor burns out) – however, varistors and varicapacitors are also used in radio engineering. Ion solutions, under the influence of the current flowing as a result of magnetic induction, change their concentration, which can change resistance. Channels in membranes can open or close, and the electrical double layer on the membranes can change (possibly related to the "non-specific benefit" of TMS). All of this can affect conductivity and capacitance, thereby generating a pulse shape different from that formed before transcranial magnetic stimulation.
>
>
> > Yevgeny, your reviewer will be angry and tell you you should never call a
>  study with n=167 preliminary. Thank you for sharing your results! It is
>  good to know that 1/f is not sensitive to hyperventilation.
>
>
> The number is quite large, but to view this as anything more than a preliminary experiment, all these observations must be considered and some discarded. Therefore, these are nothing more than experiments during the debugging of a program designed to analyze a more carefully selected sample. However, since some new information has been obtained, I offer it to your attention, but only as "food for thought," not as conclusive evidence.
> I plan to obtain results suitable for full publication, not just as a "personal communication," but to do this, I need to involve clinicians who can assess the suitability of each record for such analysis. I have neither the authority nor the expertise to analyze case histories. This requires time and effort to organize. First and foremost, I need to convince them of the usefulness of this work for them—"it's not so difficult to teach a bear to ride a bicycle than to convince a bear that it needs one." So, what I've submitted for your consideration, I'm not ready to send to a fully peer-reviewed journal until I've thoroughly checked it. If I say something stupid at work, it's my personal shame; if I publish something stupid in a fully-fledged journal, I'll disgrace my colleagues.
> And another picture, the distribution of the "alpha" by scalp (median for 167 patients)
>
> Eugen Masherov
>
> https://urldefense.com/v3/__https://ibb.co/cSVsWQBB__;!!Mih3wA!HSuCVd5XYQJMfnY5YTX3pu_k-u1q0EHR_OsYCO9ORIt1DjDy9jpQh-uwUymnqmkz2tLYcVW7RtRBynA8CsD1H5I11io$
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-- 
李景明