Thread

1. randomImmigrant · 1790804308 · focus · HN ↗

   For context, the debate in the field has been whether these are epiphenomena of the actual neuronal activity, or a meaningful driver of further activity.

   I don’t think these studies quite rest the case. As Buzsaki comments in the article, the action is in the cells to create these waves. Do the waves themselves get measured and impact what happens next? The issue at hand is: synaptic currents are stronger and we know neurons respond to them. The wave behavior is in the extracellular fluid as well, and that part we have evidence neurons don’t respond much to.

   That said, thing the article doesn’t talk about is astrocytes. Especially in the cortex, most synapses are tripartite. There’s an astrocytic end foot that sheathes the synapse and regulates how much of the bulk extracellular space has access to the synapse. And one astrocyte can touch thousands of synapses and in humans, hundreds of thousands. They also form a syncitium, through gap junctions/electrical synapses.

   Do astrocytes respond to the extracellular wave behavior, which potentially changes the extent and behavior of the syncitium, and thus impact the neurons they touch?

   That’s still an open question but that’s what I’d be interested to find out more about.

   1. HarHarVeryFunny · 1790858609 · focus · HN ↗

      Regardless of how these large scale coordinated dynamics arose, initially functional and selected for, or just epiphenomena (coupled oscillators?), it seems that they HAVE to have become functional (presumably longer range inter-region communication and sequencing) since timing does matter.

      If we assume that brain waves do have (have to have) some effect, then it seems most likely that the effect is either beneficial or detrimental compared to the alternative of uncorrelated brain activity, and therefore is being selected for or against, and as the production of millions of years of evolution, it seems the logical conclusion is that there is some functional benefit to it. The alternative is that the functional effect is merely benign, neither beneficial or detrimental, but this intuitively seems less likely.

      1. randomImmigrant · 1790866756 · focus · HN ↗

         I’m with you on finding it hard to think they’re just epiphenomena of coupled oscillators. And from the timing perspective and their spatial spread, I think it’s a solid hypothesis they actually contribute to the coupling.

         That actually happens in the narrow spatial scale of ephaptic coupling already, where neighboring neurons can sense one another firing and get primed to fire, which helps with synchronization.

         Where there’s still debate is in these larger waves, which sweep through very diverse architectures.

         And again, part of the answer may be to look at astrocytes, since they can actually tune their syncitium, and some at least can give out glutamate as a signal, and are electrically active: <a href="https:&#x2F;&#x2F;www.quantamagazine.org&#x2F;these-cells-spark-electricity-in-the-brain-theyre-not-neurons-20231018&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.quantamagazine.org&#x2F;these-cells-spark-electricity...

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