9.18b Consciousness, Coma and Related States

Physician's Notebooks 9 -- http://physiciansnotebook.blogspot.com - See Homepage


18b. Consciousness, Coma and Related States -Update (12 Septr 2021) The following headings in order as they appear in text may be used to locate by search & find or scroll down.

States of Consciousness - Alertness

Timing of States of Consciousness

Coma States & The Glasgow Coma Scale

Terminal Coma, Vegetative State or Brain Death
Consciousness is

End Note: What is non consciousness (Death)?

  States of Consciousness - Alertness: 
  The level of consciousness may be considered an analog state of alertness with the downward continuum of lowered consciousness: stupor, delirium and fugue states; pre-sleep and sleep; coma and brain death.

Timing of States of Consciousness: When we sleep, the stages are from lightest to deepest sleep and, even when awake, our state of alertness is a daily rhythm controlled by the suprachiasmatic center - a group of time-telling neurons in the hypothalamus that are clocked to a c.24-hour cycle. The cycle developed genetically for survival. (This is the natural state; each of us as modern humans consciously can adjust to rhythms of night work and artificial light but understanding the natural rhythm helps us control problems of sleep, alertness and consciousness.)
  
   One's aim in life, in my opinion, should primarily be to keep the highest state of consciousness, so long as it is not unhappy or painful, for the longest time, not sleeping when no need, and keeping maximally alert. 
   Sleep is part of consciousness: we think and experience in sleep during dreaming and we can remember. Most importantly, we can always be awakened from sleep either by external or internal stimuli. And sleep has its own descending stages of alertness, just like non sleep.

Coma States & the Glasgow Coma Scale:  Pathological continued decreases of consciousness are coma states. The Glasgow Coma Scale (GCS) is an attempt to put numbers on the level of consciousness. Think of EVM 456 (Eyes 4, Verbal 5, Movement 6) scores. 

In a patient in coma, the physician tests eyes, speech and body movement as follows:

Are (or Do) his eyes open? (Score 4) Or are the eyes closed? (Score 3 if he opens them on your spoken request, 2 if he opens them only with a painful poke or pinch, and 1 with no eye opening under any stimuli.)

Does he speak normally and know where and who he is and what the month and year? (Score 5) Or are his words confused or is he disoriented? (Score 4)  Or does he say words but meanings unintelligible? (Score 3) Or make unintelligible sounds only? (Score 2) Or is he mute? (Score 1)  

Does he move body normally? (Score 6) If not, give him a light pinch. Does he respond protectively by movements? (Score 5) Or only withdraw from pinch? (Score 4) Or assume flexed arms at elbow and wrist with legs extended (Decorticate; score 3)? Or go rigid with total body extension of arms, legs and spine, and an arched back (Decerebrate; score 2)? Or is he totally without motor response? (Score 1)

Add up the EVM sub-scores and the sum is the GCS. Deepest coma is GCS-3. A normal awake consciousness (but not necessarily highest alertness) is 15. A patient in coma: no verbal response, eyes closed would score GCS 3 to 9. A GCS 10 to 14 is lowered consciousness either stupor (a state of intense dullness) or delirium (uncontrolled excitement).

A dropping GCS with time tells the seriousness of a coma. A steady drop in the GCS number over 24 hrs or more after head injury means a poor prognosis and after 48 hrs, a GCS that has dropped to 3 means near brain death.

Terminal Coma; Vegetative (persistent—-3 weeks), (permanent—-4 mos/Brain Death) is a state that the individual's family and friends should be prepared to face. The clear-cut case is the oldster who suffers stroke from hemorrhage, cerebral artery blood clot or brain tumor; or else younger persons with serious head injury; and also where cardiac arrest after surgery, drug overdose or near sudden death or liver or kidney failure leads to brain anoxia (no or low oxygen) and coma. A good rule is: 48 hours of coma below GCS 10, a near flat electroencephalogram, and not a child or a case of hypothermia or a barbiturate OD (All of which may recover despite positive test for brain death) should be considered essentially dead - no chance for recovery. In practice, this advice is for the responsible one in consultation with a treating physician and a neurologist. The legal definition of death remains extremely strict - no heartbeat - but there is more recently a status of "brain death" - a flat EEG brainwave in the presence of other factors but with a beating heart - used where organ transplant is being considered; however, that is not a practical availability to most folks.

Consciousness is being able to see, feel, hear and otherwise know you personally exist. It is obviously private: only you the person can report what it feels like to be you. Its most succinct, definition is Descartes's Cogito ergo sum (I think; therefore, I exist). Some practical questions will be dealt with here: 

1) Consciousness and State of Alertness: You cannot retain a practical consciousness if you are just so unalert that you go into coma or fall asleep. So it depends on structures and mechanisms in the brain that produce a state of at least minimal alertness. The part of the brain required is the ascending reticular activating system (ARAS), which is a group of neurons in brainstem whose input comes from all the sensory nerves in the periphery and whose output is excitatory to the cerebral cortex through the thalamus mainly using the neurotransmitter norepinephrine. If the ARAS is disabled or disconnected, the person loses consciousness. 

2) All the scientific data suggest that each consciousness is a unique, unrepeatable entity. If you think about that, it follows that your first aim in life should be prolonging your alert consciousness by following good advices like in Physician's Notebooks to keep a healthy brain and healthy body so that your unique consciousness functions maximally for longest duration intact and lasts over time from birth to death as long as its DNA possibility and environmental reactions allow your body to last. (This assumes that your consciousness, overall, produces more pleasure & happiness than pain & unhappiness.) 

3) Consciousness requires language capability; in Descarte's definition, Cogito ergo sum, the cogito, thinking, requires a language to think in. Try thinking without language and what you get is the guessed-at, lower-animal process called zombie reaction, i.e., a very limited  bottom-up, immediate knee-jerk-like reaction to the environment in terms of danger, pain, etc. 

4) Consciousness requires the subcortical thalamus as central switchboard for cerebral cortex to be connected with the ARAS and with the periphery through the spinal cord and cranial nerves and also for many pleasure-pain relationships that are key to conscious activities. Even when the neuron groups that constitute all these brain structures remain intact, if the fibers get disconnected from one another, as in certain types of strokes and as in Alzheimer's and other forms of dementia, consciousness will be lost permanently.

5) Consciousness does not require a cerebellum, which manages coordination and timing (Proven by consciousness being retained without a cerebellum), or a corpus callosum (CC) connecting the 2 sides of the brain. (The CC are commonly cut in surgery for epilepsy with no loss of consciousness.)

 What is the mechanism of consciousness? Essentially, all the sensory experiences from the periphery (each body's environment) and also from the internal milieu of the body must be brought up to the thalamus and then parceled to appropriate parts of the cerebral cortex to be realized as a mindful experience. And, most importantly, the memory parts of the brain - working memory in prefrontal cortex, declarative memory in hippocampus temporal cortex and long term memory storage in other parts of medial temporal lobes, must be connected so that one can get a feeling of past, present, and even imagined future experiences of one's self's existence. And all this must be in the presence of a functioning ARAS that keeps us alert. 

 Human consciousness raises the consideration of consciousness in animals less higher up on the evolutionary line. Do apes, monkeys, dogs or cats have consciousness, that is, qualitatively, similar to a human's? Observation of higher mammals like dogs, cats and apes suggests a consciousness on the verge of human.

Is it possible to construct a machine that is capable of consciousness? The point here is that, presently, consciousness is an entity fashioned out of eons (ages) of organic evolution. An individual consciousness, You, for example, has a limited, c. 100-year lastingness, depending on the organic tissue of the CNS and the body that contains it. If a functional model could be constructed out of plastic/metal that not only could last thousands of years but could have parts replaced modularly, consciousness theoretically might become if not immortal, practically so. What I visualize is a machine that would be a template on which to copy an individual human consciousness before that individual's tissues reach a late state of deterioration. In that way a consciousness might be transferred from a 100-year-use body to a many-thousands-year-use machine. But to be "a consciousness", the transferred entity would have to be the unique original individual consciousness having its basic memories, its training, its pleasures and pains, and, its ability to get more educated and intelligent. It is very hard to envision that construction in our significant future. It remains science fiction. 

Consciousness is not created at birth. A newborn that lives one day is not experiencing consciousness; it has no memory or other clue to its existence. It takes at least 2 or 3 years of living and brain development before a full state of consciousness may be said to exist. But it ends abruptly with death so it must depend on the sentient physical body ( Religion-believers may differ wth this assertion but every bit of evidence over the term of human existence tells the educated person that the assertion is a fact.

 I stop the discussion here.  There is nothing in the science of the brain and digital electronics that says a consciousness template could not be constructed although, obviously, its doing would be a massive, long term project.  But it might be one of a few fitting aims for the science civilization  I envision. 

End Note:  What is non consciousness (as after Death)? We individuals who are human consciousnesses have through history struggled with the question of what happens to our own consciousness at our death and thereafter. Thrusting aside the religious hereafter with its heaven and hell or reincarnations, we are left with what each one of us has experienced in our own total, temporary loss of consciousness. (Note, not sleep or even coma because even in those states, a partial consciousness functions in dreams or hallucinations which contains memories of who the individual consciousness is.) As I think of my experiences in my 88-year life, the true experience of non-consciousness has happened when I was "put to sleep" before anesthesia for surgery by the anesthetist injecting conesciousness-losing intravenous medication. In a recent experience, I was able to glance at a clock on the wall just before I was "put to sleep" by the anesthetist. And with that plan in mind, as soon as I regained my consciousness in the recovery room I glanced at the clock on its wall. And I noted that although between 7 to 8 hours had passed with me completely having lost my consciousness, it was like no time at all had passed. The best I can describe: it was a consciousness-connected blank-out in my life timeline. Like one instant I was saying "Goodbye" jokingly to the anesthetist leaning over my arm about to inject - and the next instant I was in, seemingly, exactly the same instant opening my eyes to first awakening in the recovery room. The clock on the wall showed me that a little more than 7 hours of Earth time had passed; but to me the time passed was experienced as a nullity - a blank-out  a deletion with the time ends seamlessly put back together - of my time and space. And the only thing that connected my consciousness before and after the blank-out was my remembrance of my consciousness on awakening. (And the memory that said, Look at the clock, when I awakened.)

The non consciousness that follows death, thus, must be a personal, permanent blank-out, a blank-out one never wakes to.   End Of Chapter. To read next click 9.19 Epilepsy and Seizures and the EEG