Steven Laureys: is anyone home inside a coma patient?

Last time, we saw how consciousness and top-down attention can be pulled apart. This time, we'll pull apart two parts of consciousness: awareness and wakefulness, following Steven Laureys, a neurologist who studies disorders of consciousness.

Awareness: content of the consciousness.

Wakefulness: level of consciousness.

Their study is arguably the most medically relevant part of the study of consciousness, since there are many people in coma-like states, who have a normal sleep-wake cycle, but seems to have no awareness. Figuring out if they are aware is important for figuring out how much personhood they still have.

Warning: contains one brain selfie.

Wakefulness is fairly uncontroversial. It's so physically measurable that most people don't consider it a part of consciousness at all, and I'd agree. However, it still functions as to be a hard limit on awareness, that is
$$\text{degree of wakefulness} \geq \text{degree of awareness} $$

One example of coma patients that are very aware and awake are locked-in syndrome people. The locked-in syndrome : what is it like to be conscious but paralyzed and voiceless? (2005):

The locked-in syndrome (pseudocoma) describes patients who are awake and conscious but can't move. Acute ventral pontine lesions are its most common cause.

I remember Damasio mentioning that dorsal pontine lesions would destroy consciousness, because it's the afferent channel. Without information from the body, consciousness cannot form. Ventral pontine lesions destroy the efferent channels. Consciousness can form and feel, but can't act.

People with such brainstem lesions often remain comatose for some days or weeks, needing artificial respiration and then gradually wake up, but remaining paralyzed and voiceless, superficially resembling patients in a vegetative state or akinetic mutism... Distressingly, recent studies reported that the diagnosis of LIS on average takes over 2.5 months. In some cases it took 4–6 years before aware and sensitive patients, locked in an immobile body, were recognized as being conscious.

Time for a creepypasta! How I got locked inside my own body for 10 years and went insane and hallucinated nightmares everyday until I die.

Healthy individuals and medical professionals sometimes assume that the quality of life of an LIS patient is so poor that it is not worth living. On the contrary, chronic LIS patients typically self-report meaningful quality of life and their demand for euthanasia is surprisingly infrequent.

Once again showing how good people are at meaning-making. Actually, this got me thinking. If even LIS patients, which are essentially brains-in-vats can have some meaning in life, surely brains-in-vats can have some too... Quick, grab a philosopher!

The neural correlate of (un)awareness: lessons from the vegetative state (2005):

We can plot two dimensions of consciousness:

‘Vegetative’ is not the same as minimally conscious, and vegetative people can still have some cerebral activities. Being vegetative seems to be due to parts of the brain not talking to each other:

... disconnections in long-range pathways have been identified in the vegetative state. Moreover, recovery is accompanied by a functional restoration of the network...

vegetative patients still show cerebral activation but this seems to be limited to subcortical and ‘low-level’ primary cortical areas, disconnected from the fronto-parietal network necessary for awareness.

They have some low-level response to pain, but seems to have no higher level response, and that probably means no awareness of pain.

Electrical shocks showed robust poststimulus activation in brainstem, thalamus and primary somatosensory cortex in each of 15 well-documented vegetative patients. Importantly, higher-order areas of the pain matrix were not activated. Moreover, the activated primary somatosensory cortex was isolated from the frontoparietal network, which is thought to be required for conscious perception.

The "pain matrix" means "a set of brain areas that consistently respond to painful stimuli". No idea why it's called "matrix", probably because "matrix" originally means "that which encloses or gives origin to something".

Also, this "frontoparietal network" is not necessary for basic consciousness, if we consider people with hydranencephaly that seems to have consciousness.