4 ms·

Tried skimming the page but couldn't find the answer: do we know if the neural connection impedance is perfectly matched? It looks quite organic in shape, with

Tried skimming the page but couldn't find the answer: do we know if the neural connection impedance is perfectly matched? It looks quite organic in shape, with teardrop connections and so on, but curious how nature did that job?

phreeza 2y ago
It is not always perfectly matched, because the mismatches can actually have a "computational" purpose, but e.g. the typical branching pattern of dendrites is pretty close to being matched . There is a chapter on this in the Dayan and Abbot textbook.
- brunohaid 2y ago
  <3 awesome - this one https://boulderschool.yale.edu/sites/default/files/files/DayanAbbott.pdf https://boulderschool.yale.edu/sites/default/files/files/Day... ?
  - phreeza 2y ago
    Yes exactly. Chapter 6.3, though it is actually less detailed than I remembered.
    - brunohaid 2y ago
      Much appreciated! Maybe the impedance added some colorful garnish to your memory... :-)
      - mattkrause 2y ago
        If this is your thing, you might also want to check out Christof Koch's Biophysics of Computation. Cable theory is introduced in one of the first few chapters.
mannykannot 2y ago
That's an interesting question. One follow-up question I would have is whether impedance matching is a relevant concept here, given that the model has no inductance (I'm guessing that's because the flow of charge is in the form of ions moving radially through the membrane. If neurons were more like transmission lines, would we be susceptible to interference from distant lightning?) I also skimmed the page and saw that equation 20 is not a wave equation (as the article says, it is a diffusion equation.) Again, I am not sufficiently knowledgeable to say whether that renders the question of impedance matching moot. Update: I see from the sibling thread and its excellent reference that the refractory period, where the sodium and potassium ions are being pumped back to their starting positions, suppresses reflection.
- brunohaid 2y ago
  Sibling thread?
  - mannykannot 2y ago
    Sorry if that's not clear - I was referring to phreeza's reply to your question and the link you had posted below it, which is as far as the discussion had gone at that time. The refractory period, and its role in suppressing reflections, is mentioned in the reference you provided a link to.
    - brunohaid 2y ago
      Got it - haven't read it yet but, also thanks to your pointer, very much looking forward to!
    - deleted 2y ago
      [deleted]

phreeza 2y ago

It is not always perfectly matched, because the mismatches can actually have a "computational" purpose, but e.g. the typical branching pattern of dendrites is pretty close to being matched . There is a chapter on this in the Dayan and Abbot textbook.

brunohaid 2y ago
<3 awesome - this one https://boulderschool.yale.edu/sites/default/files/files/DayanAbbott.pdf https://boulderschool.yale.edu/sites/default/files/files/Day... ?
- phreeza 2y ago
  Yes exactly. Chapter 6.3, though it is actually less detailed than I remembered.
  - brunohaid 2y ago
    Much appreciated! Maybe the impedance added some colorful garnish to your memory... :-)
    - mattkrause 2y ago
      If this is your thing, you might also want to check out Christof Koch's Biophysics of Computation. Cable theory is introduced in one of the first few chapters.

mannykannot 2y ago

That's an interesting question. One follow-up question I would have is whether impedance matching is a relevant concept here, given that the model has no inductance (I'm guessing that's because the flow of charge is in the form of ions moving radially through the membrane. If neurons were more like transmission lines, would we be susceptible to interference from distant lightning?) I also skimmed the page and saw that equation 20 is not a wave equation (as the article says, it is a diffusion equation.) Again, I am not sufficiently knowledgeable to say whether that renders the question of impedance matching moot. Update: I see from the sibling thread and its excellent reference that the refractory period, where the sodium and potassium ions are being pumped back to their starting positions, suppresses reflection.

brunohaid 2y ago
Sibling thread?
- mannykannot 2y ago
  Sorry if that's not clear - I was referring to phreeza's reply to your question and the link you had posted below it, which is as far as the discussion had gone at that time. The refractory period, and its role in suppressing reflections, is mentioned in the reference you provided a link to.
  - brunohaid 2y ago
    Got it - haven't read it yet but, also thanks to your pointer, very much looking forward to!
  - deleted 2y ago
    [deleted]