Archive for the ‘Neurosciences’ Category

Reading forth A Universe of Consciousness (G. Tononi, G. Edelman), I go straitly in finding my hypothesis in a good book written by greater people than me! It is very amazing for me! xD

Beginning in the middle of the matter, I just come upon the notion of complexity.

The story before: neurons, synapses, biochemical signaling, excitability threshold, fibers, systems, stimulus, respondence of the brain and so on. Now, the problem is: what is that the brain being activated and we “feel”? No more than one of the biggest questions philosophers and scientists have not caught the answer to yet: what’s between brain and thoughts?

Now, the following is the architecture of my general idea.

What we can merely see is that something related of our thought really exists and it is our brain; well, please look over at this as a matter of fact, for the debate would be too long and articulated for this place to suffice. Onward, the brain is composed by neurons, glia and other strange, nasty and rack stuff; surely we can exclude that single neurons create consciousness, right? Well, so consciousness should emerge somewhere in between neurons and the whole brain.

If I am not wrong, between them we think about connections, fibers, fascicles, systems and bigger associations of all this. Soon the question “Do those things suffice for the consciousness?” arises. Some scientists’ answer “No” comes next. The last, but not least, point of view is that time has the royal scepter in all this, as I probably mentioned before, for the functions of the brain have to be integrated and synchronized in order to make out consciousness from other mind states.

This is not enough.

Neuron A can be turned on or off: it has two possible states, as neuron B does, and neuron C too, and so on. Moreover: neurons A, B, C … can be excitatory or inhibitory; namely they carry a message of “yes, go on!” or “stop here, don’t go further!” to other neurons and their signals. The only number of possible states the brain could find itself to be in ( “2 possible states” times “2 actions” times “the factorial of the number of neurons in the brain” times “the mean of the number of cells a single neuron could be linked to”) does not correspond to the integrity of consciousness. Tononi and Edelman put it into mathematical words defining a measure of the information a particular group of nervous cells carry over to the totality of a certain state of consciousness and proved that it is not the absence of coordination nor the total unison of the signals that give rise to our conscious experience. Neurons are strictly bound together with other near neurons, and less rigidly with distant ones. This type of bounding is achievable thanks to the phenomenon of reentry that let each neuron have a little feedback from the cells it is linked with, as a sort of read-confirmation in an email.

Complexity and time are the profile of the next step in the story. How do the neurons linked together by the reentry do their weird work in controlling the intricacy of conscious experience? T. and E. says that a particular state of the activated brain is not to be examined by an external viewer but we should ask ourselves what the brain itself comprehend of the situation by that particular state. The mathematical coefficient used here describes the informativeness of a certain state as its likelihood of being differentiated from the other possible states, and it is hypothesized that the brain recognizes the differences. There is not an organizer of the sensations that tells the brain what to do. It is a matter of differences: there are infinite possible states, each different from the others, and the differences are, in my opinion, strictly dominated by time.

“A C B” is as different from “A B C”  in this as “do mi sol” is different from “mi sol do” in music armony (anatomy). Moreover, “AAACCCBBB” (declared, e.g., that each letter expresses the information “for a second”) is also different from “AACCCCCBB” and “AaAcCcBbB” (in this case, B is different from b, like a Do is different from a higher Do in the scale) from “aAaCcCbBb”. In simple words, there are some types of difference sources: the sequence, the activation time, the path, the action type (excitation/inhibition) of neurons, and other ones I have not thought of yet. 🙂

fourth-dimension1In this prospective, even if it is hardly defined by philosophers, part of which regard it as a human arrangement and invention, time could largely be considered a “fourth dimension”, hence the human mind works on at least four different dimensions. I am not yet convinced that there are only four of them in the human thought, but I am too tired now to think about it! xD However, this could be a great point in the interpretation of the impossibility (or, at least, the difficulty) of a clear explanation of how the human mind works, only because the subject lives in four (or more) dimensions and we merely live in three!! In this context, I shall admit that language has a particular place, but it is not a matter of me yet!

Returning to our topic, all this can generate differencies in the shape of a thought. remember that all this is coordinates by reentry, and that results in a first attempt to a synchrony that is not a total synchrony (I said that a total synchrony is not compatible with consciousness; in fact, it is observed in REM sleep and epileptic states) but a more function-coordinated-like state.

All this is valid for both the external stimulus-dependent brain activity and the internal one (e.g. our private thoughts), clarifying some part of the living experience.

To be continued… 😉


Read Full Post »

BLINDSIGHT A patient whose visual lobes in the brain were destroyed was able to navigate an obstacle course and recognize fearful faces subconsciously.

The man, a doctor left blind by two successive strokes, refused to take part in the experiment. He could not see anything, he said, and had no interest in navigating an obstacle course — a cluttered hallway — for the benefit of science. Why bother?

When he finally tried it, though, something remarkable happened. He zigzagged down the hall, sidestepping a garbage can, a tripod, a stack of paper and several boxes as if he could see everything clearly. A researcher shadowed him in case he stumbled.

“You just had to see it to believe it,” said Beatrice de Gelder, a neuroscientist at Harvard and Tilburg University in the Netherlands, who with an international team of brain researchers reported on the patient on Monday in the journal Current Biology. A video is online at www.beatricedegelder.com/books.html.

The study, which included extensive brain imaging, is the most dramatic demonstration to date of so-called blindsight, the native ability to sense things using the brain’s primitive, subcortical — and entirely subconscious — visual system.

Scientists have previously reported cases of blindsight in people with partial damage to their visual lobes. The new report is the first to show it in a person whose visual lobes — one in each hemisphere, under the skull at the back of the head — were completely destroyed. The finding suggests that people with similar injuries may be able to recover some crude visual sense with practice.

“It’s a very rigorously done report and the first demonstration of this in someone with apparent total absence of a striate cortex, the visual processing region,” said Dr. Richard Held, an emeritus professor of cognitive and brain science at the Massachusetts Institute of Technology, who with Ernst Pöppel and Douglas Frost wrote the first published account of blindsight in a person, in 1973.

The man in the new study, an African living in Switzerland at the time, suffered the two strokes in his 50s, weeks apart, and was profoundly blind by any of the usual measures. Unlike people suffering from eye injuries, or congenital blindness in which the visual system develops abnormally, his brain was otherwise healthy, as were his eyes, so he had the necessary tools to process subconscious vision. What he lacked were the circuits that cobble together a clear, conscious picture.

The research team took brain scans and magnetic resonance images to see the damage, finding no evidence of visual activity in the cortex. They also found no evidence that the patient was navigating by echolocation, the way that bats do. Both the patient, T. N., and the researcher shadowing him walked the course in silence.

The man himself was as dumbfounded as anyone that he was able to navigate the obstacle course.

“The more educated people are,” Dr. de Gelder said, “in my experience, the less likely they are to believe they have these resources that they are not aware of to avoid obstacles. And this was a very educated person.”

Scientists have long known that the brain digests what comes through the eyes using two sets of circuits. Cells in the retina project not only to the visual cortex — the destroyed regions in this man — but also to subcortical areas, which in T. N. were intact. These include the superior colliculus, which is crucial in eye movements and may have other sensory functions; and, probably, circuits running through the amygdala, which registers emotion.

In an earlier experiment, one of the authors of the new paper, Dr. Alan Pegna of Geneva University Hospitals, found that the same African doctor had emotional blindsight. When presented with images of fearful faces, he cringed subconsciously in the same way that almost everyone does, even though he could not consciously see the faces. The subcortical, primitive visual system apparently registers not only solid objects but also strong social signals.

Dr. Held, the M.I.T. neuroscientist, said that in lower mammals these midbrain systems appeared to play a much larger role in perception. In a study of rats published in the journal Science last Friday, researchers demonstrated that cells deep in the brain were in fact specialized to register certain qualities of the environment.

They include place cells, which fire when an animal passes a certain landmark, and head-direction cells, which track which way the face is pointing. But the new study also found strong evidence of what the scientists, from the Norwegian University of Science and Technology in Trondheim, called “border cells,” which fire when an animal is close to a wall or boundary of some kind.

All of these types of neurons, which exist in some form in humans, may too have assisted T. N. in his navigation of the obstacle course.

In time, and with practice, people with brain injuries may learn to lean more heavily on such subconscious or semiconscious systems, and perhaps even begin to construct some conscious vision from them.

“It’s not clear how sharp it would be,” Dr. Held said. “Probably a vague, low-resolution spatial sense. But it might allow them to move around more independently.”


Published: December 22, 2008

Read Full Post »

My neuro-cognitive project is getting richer and richer any moment I have the time to think about it.
in recent times, I have tried to get some professors’ views about the main outlines I underlined for my potential theory. I was able to draw attention to and specify some of the points I wrote somewhere above here.
Unfortunately, as time goes by I cannot find any occasion until the end of the winter exams session to think of it, so I fear I would need some concentration and relax in order to make it clearer and picture it to the consideration of my tiny public.
The only thing I might tell you by now is that its possible name would assume the concept of aura as the key-role aspect of that theory, from the point of view that thoughts are represented by the idea of the aura of electric signaling pathways neurons create as we think.
More aspects of this rubbish of mine will be published, as I just said, as soon as relax would permit. 😉


Read Full Post »

The first part of my cognitive sciences studies had me learn a huge
amount of information and theories about the structures of mental
functions. What my mind was curious about is the role of complexity of
networks neurons create each other, in particular considering:

  • the specific function of every single cell
  • the pathways bio-electric signals run;
  • the intricate neuronal stimulation-inhibition process through time;
  • the idea of thinking being the result of the synchrony of mental activity.

I can not find any study about it through the web. There is the
possibility that this is a well-known theory I am about to study the
soonest tomorrow, but I am doubtful this approach has ever been thought

My central idea is simple. Linking the basic concepts of
neuronal structure (anatomy), activity (physiology) with more
philosophical ideas about mind, it is obvious that something in between
the chain of processes from the molecules to the high cognitive
processes is missing. I, from my low and uncultured position, think
time has the key role in all this chain.

For I have not enough
time to explain my ideas the best way, I postpone a more exhaustive
explanation to a proper occasion, hoping you would be interested again!

Read Full Post »