Consciousness: Egnor on dualism: another example II (General)

by David Turell , Sunday, August 26, 2018, 20:11 (2279 days ago) @ David Turell

Quotes from the Sci. am. article on looking at degrees of consciousness:

"in clinical practice we need unambiguous criteria. In that setting, everyone needs to know what we mean by an “unconscious” patient. Consciousness is not “all or nothing.” We can be more or less awake, more or less conscious. Consciousness is often underestimated; much more is going on in the brains of newborns, animals and coma patients than we think.

" is it possible to study something as complex as consciousness?

" For example, without brain scanners we would know much, much less than we now do. We study the damaged brains of people who have at least partially lost consciousness. We examine what happens during deep sleep, when people temporarily lose consciousness. We’ve also been working with Buddhist monks because we know that meditation can trigger alterations in the brain; connections that are important in the networks involved in consciousness show changes in activity. Hypnosis and anesthesia can also teach us a great deal about consciousness.

"What processes in the brain create consciousness?

"Two different networks seem to play a role: the external, or sensory, network and the internal self-consciousness network. The former is important for the perception of all sensory stimuli. To hear, we need not only ears and the auditory cortex but also this external network, which probably exists in each hemisphere of the brain—in the outermost layer of the prefrontal cortex as well as farther back, in the parietal-temporal lobes. Our internal consciousness network, on the other hand, has to do with our imagination—that is, our internal voice. This network is located deep within the cingulate cortex and in the precuneus. For us to be conscious of our thoughts, this network must exchange information with the thalamus.

***

"How do we know whether a coma patient who has awakened is conscious?

"For that we use the Glasgow Coma Scale. The physician says, “Squeeze my hand.” Or we observe whether the patient responds to sounds or touch. If patients do not respond, the condition used to be called “vegetative”; they appear to be unconscious. If a patient responds but is unable to communicate, we categorize the consciousness as “minimal.” Such patients may, for example, follow a person with their eyes or answer simple questions. If we pinch their hand, they will move it away. But these signs of consciousness are not always evident, nor do we see them in every patient. A patient who awakens from a coma may also develop a so-called locked-in syndrome,being completely conscious but paralyzed and unable to communicate, except through eye blinks.

***

"How can minimal consciousness be distinguished from locked-in syndrome?

"Minimally conscious patients can barely move and are not completely aware of their surroundings. In other words, their motor and mental abilities are limited. Locked-in patients can’t move either, but they are completely conscious. They have suffered a particular type of injury to the brain stem. Their cerebral cortex is intact but is disconnected from their body. All they can move is their eyes. This is why diagnosis is so difficult. Just because patients cannot move does not mean they are unconscious.

***

"How can a person who cannot move manage to communicate?

"To communicate with a minimally conscious patient for the first time, we placed him in a scanner. Of course, the scanner cannot tell us directly whether someone is saying yes or no. But there are a couple of tricks. For example, we can tell the patient, “If you want to say yes, imagine that you are playing tennis. If you intend to say no, make a mental trip from your front door to your bedroom.” “Yes” answers activate the motor cortex; “ no” answers engage the hippocampus, which plays a role in spatial memory. Because these two regions of the brain are located far apart from each other, it is pretty easy to tell the difference between yes and no. From that point on, we can ask the patient pertinent questions.

"What other potential techniques do you have in the pipeline?

"In the future, it may be possible to read brain signals using scalp electrodes and a brain-computer interface. This would make communication much quicker and less costly than with a brain scanner. We have also found that it is possible to examine a person’s pupils: we ask patients to multiply 23 by 17 if they intend to say yes. This difficult problem causes the patients to concentrate, and their pupils will dilate slightly as a result. If we direct a camera at their eyes and a computer analyzes the signals, we can determine quite quickly whether the intended answer is positive or negative.

"Can consciousness be stimulated?

"Yes, by transcranial direct-current stimulation. Using scalp electrodes, we can stimulate particular regions of the brain. By careful placement, we can select the region responsible for speech, which is connected with consciousness. If I stimulate this region of the brain, the patient may hear and understand what I say. In some cases, a patient has been able to communicate transiently for the first time after a 20-minute stimulation—by, for example, making a simple movement in response to a question. Other patients have been able to follow a person with their eyes. (my bold)

Comment: Note he uses electricity to stimulate thought. And his scans and electrodes view thought/consciousness as electrical.