I’ve been meaning to make a blurb about this for awhile, but it keeps slipping my mind. This means this may be a bit rougher than I intend because I haven’t really thought about how to translate it yet and will probably need to come back and edit quite a bit for errors until I do.
Especially relevant to the recent discussions about how the ponto/cerebellar nuclei contribute state updates to cortical and limbic circuits should be the question… yeah but how?
If the dorsal and ventral pathways are “functional inversions” of each other, how is it even possible for the write to occur without some type of translation occurring?
To which I’d say, Good question! That’s using your noodle! Or more likely just grin like an idiot because it meant you were actually stepping through the path of information and seeing a non-obvious gap.
Within the big valence nuclei and scattered throughout the cerebral cortex there are indeed “switching” pathways which have the ability to transform a signal from one type to another. The valence nuclei have mechanisms which are able to directly perform the differential calculation and write directly to the stream. The most well known (I think?) example of this mechanism are the putamen/globes direct manipulation of the stream.
Less well known are a class of switches in cortical areas called chandelier cells, which work similarly on stored information. “Cognitive speed” as a whole (separate from “performance” which is a larger concept) appears to largely be a construct of this class of cells. More specifically, the speed at which new information can be integrated into global processing is likely entirely the result of this class of cells.
These cells allow the brainstem to write directly to the stream in a bottom up fashion, and are “fast” class interneurons. It also allows writes directly outside the normal valence weighting mechanism which can be both good and bad.
Under the model (this is fairly recent), all “hallucinations” or perception distortions initiate in the brainstem. And we can define persistent hallucinations as the brainstem “abusing” these fast write paths to overwrite the low level information our maps are built up from.
This is part of the reason why these distortions of perception are so pervasive and invisible for the individual experiencing them, they are built from the data pulled from exactly the same low level processing components the standard stream is built from. Our “experience” is dorsal/ventral weighting, but this happens before that.
I’d like to propose that a significant portion of the “big” flavors of “autism/schizophrenia” are actually a set of stable phenotypes which weight this low level write function more heavily than “normal”, all the way up to perhaps equal weight to the general stream itself.
edit: Cognitively, why do dorsals think in terms of “systems” instead of “objects” like ventrals do? Because dorsals are doing these direct olivo-pontine writes and bypassing a lot of the cerebellar processing which imposes that. Why can’t some people seem to “think for themselves”? Because the have a low ability to access these pathways to do direct writes, everything must be structured through the stream/cerebellum to be written.
I just realized that we could probably develop a test for this effect based on response to asynchronous information. Hrm.
Also, it’s probably more correct to say that “fast” thinkers are utilizing these circuits, while “slow” thinkers are doing full stream analysis. “Slow” thinking is generally more “thorough” because it’s working on the full stream, while “fast” thinking only on the data itself. Integration itself is separate, and an artifact of immune system performance.
edit 2: Also, yes, there’s still an astrocyte pulling the strings of these connections. Neurons in and of themselves are *transmitters* rather than processors. This answers more “how does an astrocyte ingest both dorsal and ventral information to make the differential in the first place?”
In my brain, the calcium wave is an artifact of the propagation wave, and the dynamics of the astrocytes flipping these circuits shapes the actual stored differential. This is pretty similar to the “electrical waves” we see in neurons.
edit 3: Huh… Maybe burying this a little bit but things that “feel” are ventral valenced. It’s the literal effect of ventral flavoring of the stream. I want to do some acid while doing cerebellar stimulation and see what happens…
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Experience shapes chandelier cell function and structure in the visual cortex
An adaptive behavioral control motif mediated by cortical axo-axonic inhibition
Synaptic boutons are smaller in chandelier cell cartridges in autism
Microglia regulate chandelier cell axo-axonic synaptogenesis – Really important for the consolidation after the write because it’s not always going to be a clean differential. This is likely one of the mechanical differences between “Schizophrenia” and “Dorsal Autism”.
Neuromodulatory control of inhibitory network arborization in the developing postnatal neocortex – Underlying developmental mechanic of dorsal dominant phenotypes as a whole.