Hacker News Reader

Comment by ethanbond | Hacker News Reader

The split brain experiments very very clearly indicate that different parts of the brain can independently conduct behavior and gain knowledge independently of other parts.

How or if this generalizes to healthy brains is not super clear, but it does actually provide a good explanatory model for all sorts of self-contradictory behavior (like addiction): the brain has many semi-independent “interests” that are jockeying for overall control of the organism’s behavior. These interests can be fully contradictory to each other.

Correct, ultimately we do not know. But it’s actually a different question than your rephrasing.

View on HN

Given that functional localization varies widely from subject to subject per modern neuroimaging, how are split brain experiments more than crude attempts to confirm functional specialization (which is already confirmed without traumatically severing a corpus callosum) "hemispheric" or "lateral"?

Neuroimaging indicates high levels of redundancy and variance in spatiotemporal activation.

Studies of cortices and other tissues have already shown that much of the neural tissue of the brain is general purpose.

Why is executive functioning significantly but not exclusively in the tissue of the forebrain, the frontal lobes?

Because there’s a version of specialization that is, “different regions are specialized but they all seem to build consensus” and there’s a version that is “different regions are specialized and consensus does not seem to be necessary or potentially even usual or possible.”

These offer very different interpretations of cognition and behavior, and the split brain experiments point toward the latter.

Functional specialization > Major theories of the brain> Modularity or/and Distributive processing: https://en.wikipedia.org/wiki/Functional_specialization_(bra... :

> Modularity: [...] The difficulty with this theory is that in typical non-lesioned subjects, locations within the brain anatomy are similar but not completely identical. There is a strong defense for this inherent deficit in our ability to generalize when using functional localizing techniques (fMRI, PET etc.). To account for this problem, the coordinate-based Talairach and Tournoux stereotaxic system is widely used to compare subjects' results to a standard brain using an algorithm. Another solution using coordinates involves comparing brains using sulcal reference points. A slightly newer technique is to use functional landmarks, which combines sulcal and gyral landmarks (the groves and folds of the cortex) and then finding an area well known for its modularity such as the fusiform face area. This landmark area then serves to orient the researcher to the neighboring cortex. [7]

Is there a way to address the brain with space-filling curves around ~loci/landmarks? For brain2brain etc

FWIU, Markham's lab found that the brain is at max 11D in some places; But an electron wave model (in the time domain) may or must be sufficient according to psychoenergetics (Bearden)

> Distributive processing: [...] McIntosh's research suggests that human cognition involves interactions between the brain regions responsible for processes sensory information, such as vision, audition, and other mediating areas like the prefrontal cortex. McIntosh explains that modularity is mainly observed in sensory and motor systems, however, beyond these very receptors, modularity becomes "fuzzier" and you see the cross connections between systems increase.[33] He also illustrates that there is an overlapping of functional characteristics between the sensory and motor systems, where these regions are close to one another. These different neural interactions influence each other, where activity changes in one area influence other connected areas. With this, McIntosh suggest that if you only focus on activity in one area, you may miss the changes in other integrative areas.[33] Neural interactions can be measured using analysis of covariance in neuroimaging [...]

FWIU electrons are most appropriately modeled with Minkowski 4-space in the time-domain; (L^3)t

Neuroplasticity: https://en.wikipedia.org/wiki/Neuroplasticity :

> The adult brain is not entirely "hard-wired" with fixed neuronal circuits. There are many instances of cortical and subcortical rewiring of neuronal circuits in response to training as well as in response to injury.

> There is ample evidence [53] for the active, experience-dependent re-organization of the synaptic networks of the brain involving multiple inter-related structures including the cerebral cortex.[54] The specific details of how this process occurs at the molecular and ultrastructural levels are topics of active neuroscience research. The way experience can influence the synaptic organization of the brain is also the basis for a number of theories of brain function

"Representational drift: Emerging theories for continual learning and experimental future directions" (2022) https://www.sciencedirect.com/science/article/pii/S095943882... :

> Recent work has revealed that the neural activity patterns correlated with sensation, cognition, and action often are not stable and instead undergo large scale changes over days and weeks—a phenomenon called representational drift. Here, we highlight recent observations of drift, how drift is unlikely to be explained by experimental confounds, and how the brain can likely compensate for drift to allow stable computation. We propose that drift might have important roles in neural computation to allow continual learning, both for separating and relating memories that occur at distinct times. Finally, we present an outlook on future experimental directions that are needed to further characterize drift and to test emerging theories for drift's role in computation.

So, to run the same [fMRI, NIRS,] stimulus response activation observation/burn-in again weeks or months later with the same subjects is likely necessary given Representational drift.

"EM Wave Polarization Transductions" Lt. Col. T.E Bearden (1999) :

> Physical observation (via the transverse photon interaction) is the process given by applying the operator ∂/∂t to (L^3)t, yielding an L3 output.

You're ignoring several confounders and conflating several loosely related things that I'm not even sure what the point you're making is anymore.

To begin with, the split-brain experiments don't provide clear or strong evidence for anything given the small sample size, heterogeneity in procedure (i.e. was there complete comissurotomy or just callosotomy) and the elapsed time between neuropsychiatric evaluation and initial procedures which relies on the assumption that adaptation does not occur and neuroplasticity is not a thing. The split-brain experiments are notable because the lab experiments SUGGEST the lack of communication between two hemispheres and a split conscious however this is paradoxical with everyday experience of these patients, far from providing evidence for anything.

Ignoring that for a moment, how do the split-brain experiments support 'the brain has many semi-independent “interests” that are jockeying for overall control of the organism’s behavior'?

How is addiction self-contradictory exactly and what does this have to do with split-brain?

If your point is that different parts of the brain (e.g. the reward system and the executive function regions) have different roles this isn't really debatable, obviously different parts of the brain are all doing their individual jobs and the most widely accepted theory is that these are integrated in some unknown mechanism by a single consciousness which remains in control.

Your original statement of: does the brain know what the brain is doing. The answer so far does not seem to be "yes."

Suggests you're arguing that the brain has many different consciouses that are in a constant battle, i.e. there is not a unified consciousness in control of behavior.

To take your addiction example, the brain is very much aware of what it is doing and addiction is not self-contradictory because short term rewards are being valued above long-term ones and health of the organism. The reward system model provides an excellent neurobiological explanation for addiction.

This is not directly evidenced by either addiction or the split brain experiments and is at best a hypothetical model hence why it's a theory and my original response to your statement.

I'm not "ignoring" them at all. I'm saying that they point to interesting questions that are not answered.

> The split-brain experiments are notable because the lab experiments SUGGEST the lack of communication between two hemispheres and a split conscious however this is paradoxical with everyday experience of these patients, far from providing evidence for anything.

It is not "paradoxical" but yes it does conflict with some reported experience. However, even healthy individuals often report being "of two minds" or struggling to "make up their [singular] mind." Why are these utterances to be dismissed while the also-subjectively-reported sensation of unitary experience is taken as fact?

> Suggests you're arguing that the brain has many different consciouses that are in a constant battle, i.e. there is not a unified consciousness in control of behavior.

I wouldn't characterize my position as "many different consciousnesses," but rather that consciousness is dispersed across (at least) the brain. In some scenarios (such as a corpus callosotomy) and perhaps in more everyday scenarios - perhaps all day every day - that dispersed activity can fall out of internal "synchronization." Anyway, you provided the exact same interpretation in the previously quoted section: "the lab experiments SUGGEST the lack of communication and a split consciousness."

You just go one step further of prioritizing the subjectively reported sensation of unitary consciousness over also-subjectively-reported sensation of non-unitary consciousness. That's your prior taking hold, not mine, and not actual evidence.

You yourself admit we do not know the mechanism (if any exists) by which the activity in various parts of the brain are integrated. We do not know if this process actually even occurs!

Regarding addiction, it is very, very commonly reported that addicts will go into "autopilot" like states while satisfying their addictions and only "emerge" when they have to face consequences of their behaviors. Again, subjectively reported, but so is the experience of unitary consciousness! If we cannot trust one then we shouldn't take it as granted that we can trust the other.

I get the sense you think you're arguing against some firmly held belief or a model I'm proposing as fact: you're not! We're both saying "we don't know much about how this works." And no, neurochemical mechanisms are not complete answers to how brain activity ladders up to conscious experience, similar to how a molecular model of combustion cannot explain much about urban traffic patterns.

I'm arguing against the strength of your statements based on methodologically unsound experiments that do not "very very clearly indicate" anything beyond pose a few questions for which there are several different hypothetical answers. All of which have zero evidence behind them.

Similarly, the initial comment of 'does the brain know what the brain is doing. The answer so far does not seem to be "yes."' is misleadingly suggesting there is a shred of evidence supporting that the answer is 'no' or that the answer is 'not yes'. There are no answers so far, just questions.

If anything, there are more unified consciousness hypotheses than otherwise, although if you refer back to my original reply I did not make this assertion: 'I think the correct statement is "so far the answer is we don't know"'

> It is not "paradoxical" but yes it does conflict with some reported experience.

Rather than belabour the experiment results and implications here is a great peer-reviewed article by experts in the field: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7305066/

> Regarding addiction, it is very, very commonly reported that addicts will go into "autopilot" like states while satisfying their addictions and only "emerge" when they have to face consequences of their behaviors. Again, subjectively reported, but so is the experience of unitary consciousness! If we cannot trust one then we shouldn't take it as granted that we can trust the other.

The dopamine reward system understanding (which by the way is probably the most well-validated and widely believed model in neurobiology) provides a rational explanation for addiction.

You haven't explained what is self-contradictory, that a few case reports exist of patients claiming they went in and out of consciousness? That's not a contradiction.

The split brain experiments clearly indicate exactly what I said they clearly indicate. To refresh: "that different parts of the brain can independently conduct behavior and gain knowledge independently of other parts".

From your own linked article: "In short, callosotomy leads to a broad breakdown of functional integration ranging from perception to attention."

If the dopamine reward system is the full answer, then what explains drug addicts anguishing about their addiction while simultaneously actively seeking out their next hit? What part of the brain is producing the anguish if the whole behavior is conclusively described by the dopamine reward system?

Breakdown of functional integration =/= different parts of the brain can independently conduct behavior and gain knowledge.

Still not sure what the contradiction is, is it regret now? Cause that isn’t contradictory.

It’s pretty simple, drugs feel really good when you take them so a single consciousness prioritizes that feeling over long term interests. When one is not taking them and facing the consequences of those decisions they feel bad. To make the bad feelings go away one takes more drugs and the cycle repeats.

Reply on news.ycombinator.com