We have been discussing about Consciousness in almost all the articles so far. By this time one must be aware that we are conscious; one does not need anything or anyone else to confirm it. Is it some kind of esoteric or mystical idea? We have seen the Philosophical, Psychological and Religious views but what does the medicine say? Let us look into what the neural science says. Already we had started to look at this with the article, ‘Insight’ about Dr. Jill Bolte Taylor, we will continue further in depth. Do not miss to watch the BBC video on consciousness in the ‘YouTube’ embedded at the end of this article.
Continuous Change; During our life 500,000 cells die each second, each minute 30 million cells die, and each day about 50 billion cells in our body die and are being replaced, resulting in a new body about each year.
Permanency: The only thing that is permanent during our life time is consciousness. Consciousness presents timely as well as everlasting experiences. Is there a start or an end to consciousness? Where does it start – just a brain activity or something else? There is no conclusive verdict. But still looking into the differing views will give you an insight.
One view point is that brain is the origin and centre of consciousness.
Biological Definition of consciousness is, ‘momentary creation of neural patterns which describe a relation between the organisms on the one hand, and an object or an event, on the other’. These composite neural patterns describe a state we call the ‘self’.
· Key mechanisms of consciousness are implemented in the midbrain and basal diencephalon.
· In case of brain death, neurological examination of the patient demonstrates no response to any stimulation, aside the reflexes mediated by the spinal cord. Brain death is the legal equivalent of death in many societies.
· Brain can perform complete cognitive and executive functions without being aware of them; the neuronal signatures distinguish the unconscious from the conscious process.
· Lesions (damages) in the subsystems (of the brain) prevent the conscious experience of the contents provided by the respective subsystem, consciousness per se is not jeopardised.
· It is only after the lesions (damages) affecting the global coordination of cortical functions that consciousness is abolished.
· Contents of the conscious experience are represented by distributed codes.
· Selection of responses for further processing appears to be through synchronisation rather than through enhancing the discharge frequency.
· Likewise suppression is not achieved by inhibiting responses but by de-synchronisation.
· …thus not the power of the local stimulus but their precise phase locking across a widely distributed cortical network was the earliest signature of the conscious processing…
· The local coordination of computations within specific cortical areas is achieved by fast ticking clocks such as beta and gamma oscillations, while global and sustained integration of local results is achieved at a slower pace by low frequency oscillations.
Clear sensory and complex perceptual processes during a period of apparent clinical death challenge the concept that consciousness is localized exclusively in the brain.
The description of near death experience of a patient,
“All of my life up till the present seemed to be placed before me in a kind of panoramic, three-dimensional review, and each event seemed to be accompanied by a consciousness of good or evil or with an insight into cause or effect.
Not only did I perceive everything from my own viewpoint, but I also knew the thoughts of everyone involved in the event, as if I had their thoughts within me.
This meant that I perceived not only what I had done or thought, but even in what way it had influenced others, as if I saw things with all-seeing eyes. And so even your thoughts are apparently not wiped out. And all the time during the review the importance of love was emphasised. Looking back, I cannot say how long this life review and life insight lasted, it may have been long, for every subject came up, but at the same time it seemed just a fraction of a second, because I perceived it all at the same moment. Time and distance seemed not to exist. I was in all places at the same time, and sometimes my attention was drawn to something, and then I would be present there.”
- (Near Death Experience, Consciousness, and the brain - Pim Van Lommel)
The brain contains about 100 billion neurons, 20 billion of which are located in the cortex. Each neuron has tens to hundreds of synapses. … Transportation of information along neurons occurs predominantly by means of their action potentials, and during cerebral activity the sum of all electromagnetic fields of billions of neurons continuously changes each nanosecond. Neither the number of neurons, nor the precise shape of the dendrites, nor the position of synapses, nor the firing of individual neurons seem to be crucial for information processing properties, but the derivative, the fleeting, highly ordered patterns of these changing electromagnetic fields generated along the dendritic trees of specialized neuronal networks…. This self-organization can be compared with a vortex in running water.
(Pim Van Lommel)
1. Consciousness -- What Is It? L. Dossey, B. Greyson, P.A. Sturrock, and J. B.Tucker
2. Near Death Experience, Consciousness, and the brain - Pim Van Lommel (http://www.pimvanlommel.nl/files/publicaties/Near-Death%20Experience_Consciousness%20and%20the%20Brain.pdf )
4. The Neurology of consciousness – Steven Laureys & Giulio Tononi
5. Visual Consciousness – Kevin O’ Regan & Alva Noe.