@paulhanke,
Please note that over the next 3 or so weeks, my posting will be sporadic; I apologize for that, and ask for your understanding.
paulhanke;90081 wrote:... however, my point is that in split brain patients the conclusion that both hemispheres are conscious can be attributed to their symmetry of dynamical organization - not to some notion of "'brain' is conscious" ... add to that the hypothesis that if you instead severed a brain into a top hemisphere and a bottom hemisphere you would not end up with a split brain patient but rather a vegetable, and it would appear that the "dynamical organization" perspective is more consistent with things than is the "'brain' is conscious" perspective ... that is, in a "dynamical organization" perspective, it should make a difference how you cut things up, whereas in a "'brain' in conscious" perspective, it should not, yes? ...
It seems to me that a little further inspection would best be done, and taken into consideration here. Firstly, we do not usually have the idea of horizontal or coronal (vertical right to left plane of cut) hemispheric divisions. The neocortex is often called the cerebral hemisphere, and since it is heavily divided by nature at the sagittal fissure which goes down to the callosal sulcus from the rostral, to the cerebellar hemisphere, the colliculi (inferior/superior), llateral geniculate, and the pinal gland area of the midbrain at the dorsal (or caudal), it is seen as two hemispheres. Then, in the case of full or partial cutting of the several commissures, none of the ventricles
(1) are being cut into
(although there is some CSF in the subarachnoid space between the arachnoid membrane and pia matter which have to be cut through after removing the skull cut), and none of the major blood veins are severed, and the severage of the those axons do not evidence causing any neuron degeneration. Therefore, what has happened is that simply the pryrmidal neurons in layers two and three of the two cerebral hemispheres cannot 'talk' to each other; it is not a matter of actually severing the brain.
If we were to sever the brain across a coronal plane, say making a complete cut from the occipital lobe, across the top of cerebellum, into the midbrain/brainstem area, the optic nerve (II), and out from the orbital gyri area, we would, as you have pointed out, have not just a vegetable, but a dead person. Even if we were to make a complete severage from the CC down the entire length of midbrain and brainstem, we'd have a dead person.
While there is more symmetry of the two cerebral hemispheres, there is asymmetry as well. While the modules will be in both hemispheres, their volume or builds will sometimes be different. The point of both cortical sheets being seen as dynamic systems on their own, or, when layers II and III have normal communication abilities, a single dynamic system, in no way distracts from their being seen as being conscious, but is very much part and parcel with it. It is not a matter of symmetry which makes conscious because the hypothalamus has a state of conscious (not consciousness) just as V5 (MT) of striate area does, but there is much less symmetry in their essential builds. It is a matter of being a certain dynamic system, and that is as building to a state of conscious operation, so there is no contrast, actually.
Therefore, paulhanke, let me reassure you (just in case) that there is nothing wrong with the accuracy, nor the advantage of usage, of the descriptive phrase, '
brain is conscious.' I think it is very much tied up with the same thing as the '
brain is a dynamic system,' and so see no problem with using either expression.
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paulhanke;90084 wrote:... but I think I remember seeing somewhere a report of a split brain patient that spoke from his LH but wrote from his RH - and if you posed an abstract question to one and then the other hemisphere ("What do you want to be when you grow up?") you could end up with different answers ...
I wonder if that had been from here . . . ?
KaseiJin;89977 wrote:2. There are cases of more language distribution than usual into RH, and one interesting one in particular, one V.J. who generates spoken language exclusively from LH (Broca's and Wernicke's areas), but who generates written language exclusively from RH.
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Just kind of playing around here; and maybe at the same time encourage those good reading habits. . . hee, hee, hee. . .
1. The ventricles suppy the brain with cerebraspinal fluid (CSF) and helps with neuromodulator and hormone signaling, among other things.
