Dr. Pim van Lommel, M.D.: Continuity of Consciousness - Neurophysiology in a Normal Functioning Brain
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6. NEUROPHYSIOLOGY IN A NORMAL FUNCTIONING BRAIN
For decades, extensive research has been done to localize consciousness and memories inside the brain, so far without success. In connection with the unproven assumption that consciousness and memories are produced and stored inside the brain, we should ask ourselves how a non-material activity such as concentrated attention or thinking can correspond to an observable (material) reaction in the form of measurable electrical, magnetic, and chemical activity at a certain place in the brain,23-25 even an increase in cerebral blood flow is observed during such a non-material activity as thinking.26 Neurophysiological studies have shown these aforesaid activities through EEG, magnetoencephalography (MEG), magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning. Specific areas of the brain have been shown to become metabolically active in response to a thought or feeling. However, those studies, although providing evidence for the role of neuronal networks as an intermediary for the manifestation of thoughts, do not necessary imply that those cells also produce the thoughts. Direct evidence of how neurons or neuronal networks could possibly produce the subjective essence of the mind and thoughts is currently lacking. It is also not well understood how to explain that in a sensory experiment, the subject stated that he was aware (conscious) of the sensation a few thousands of a second following the stimulation, whereas neuronal adequacy in the subject’s brain wasn’t achieved until a full 500 msec following the sensation. This experiment has led to the so-called delay-and-antedating hypothesis,27 and it is a challenge to our current neurophysiological theories, as well as phenomena like anticipatory activation, or presentiment,28 with changes on MRI up to 3 seconds preceding emotional stimuli. 29
The brain contains about 100 billion neurons, 20 billion of which are situated in the cerebral cortex. Several thousand neurons die each day, and there is a continuous renewal of the proteins and lipids constituting cellular membranes on a time-span basis ranging from several days to a few weeks.30 During life the cerebral cortex continuously adaptively modifies its neuronal network, including changing the number and location of synapses. All neurons show an electrical potential across their cell membranes, and each neuron has tens to hundreds of synapses that influence other neurons. Transportation of information along neurons occurs predominantly by means of action potentials, differences in membrane potential caused by synaptic depolarization and hyperpolarization. The sum total of changes along neurons causes transient electric fields and therefore also transient magnetic fields along the synchronously activated dendrites. During cerebral activity, these electrical and magnetic patterns of the 100 billion neurons change 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 4-dimensional (space and time) patterns of the electromagnetic fields generated along the dendritic trees of specialized neuronal networks. These patterns should be thought of as the final product of chaotic, dynamically governed self-organization.31
The influence of external localized magnetic and electric fields on these constant changing electromagnetic fields during normal functioning of the brain should now be mentioned. Neurophysiological research is being performed using transcranial magnetic stimulation (TMS),32 in the course of which localized magnetic fields are produced. TMS can excite or inhibit different parts of the brain, depending of the amount of energy given, allowing functional mapping of cortical regions and creation of transient functional lesions. It allows assessing the function in focal brain regions on a millisecond scale, and it can study the contribution of cortical networks to specific cognitive functions. TMS can interfere with visual and motion perception, by interrupting cortical processing for 80-100 milliseconds. Intracortical inhibition and facilitation obtained during paired-pulse studies with TMS reflect the activity of interneurons in the cortex. Also TMS can alter the functioning of the brain beyond the time of stimulation, but it does not appear to leave any lasting effect.32
Interrupting the electrical fields of local neuronal networks in parts of the cortex also disturbs the normal functioning of the brain. By localized electrical stimulation of the temporal and parietal lobe during surgery for epilepsy the neurosurgeon and Nobel prize winner Wilder Penfield could sometimes induce flashes of recollection of the past (never a complete life review), experiences of light, sound or music, and rarely a kind of out-of-body experience (OBE).33,34 These experiences did not produce any life-attitude transformation.
The effect of the external magnetic or electrical stimulation depends on the intensity and duration of energy given. There may be no clinical effect; sometimes an effect occurs when only a small amount of energy is given. But during stimulation with higher energy, inhibition of local cortical functions occurs by extinction of their electrical and magnetic fields (personal communication Dr. Olaf Blanke, neurologist, Laboratory for Presurgical Epilepsy Evaluation and Functional Brain Mapping Laboratory, Department of Neurology, University Hospital of Geneva, Switzerland). Blanke recently described a patient with induced OBE by inhibition of cortical activity caused by more intense external electrical stimulation of neuronal networks in the gyrus angularis in a patient with epilepsy.35
We have to conclude that localized artificial stimulation with real photons (electrical or magnetic energy) disturbs and inhibits the constantly changing electromagnetic fields of our neuronal networks, thereby influencing and inhibiting the normal functions of our brain. Could consciousness and memories be the product or the result of these constantly changing fields of photons? Could these photons be the elementary carriers of consciousness?31
Some researchers try to create artificial intelligence by computer technology, hoping to simulate programs evoking consciousness. But Roger Penrose, a quantum physicist, argues that “Algorithmic computations cannot simulate mathematical reasoning. The brain, as a closed system capable of internal and consistent computations, is insufficient to elicit human consciousness.”36 Penrose offers a quantum mechanical hypothesis to explain the relation between consciousness and the brain. And Simon Berkovitch, a professor in Computer Science of the George Washington University, has calculated that the brain has an absolutely inadequate capacity to produce and store all the informational processes of all our memories with associative thoughts. We would need 1024 operations per second, which is absolutely impossible for our neurons.37 Herms Romijn, a Dutch neurobiologist, comes to the same conclusion.30 One should conclude that the brain has not enough computing capacity to store all the memories with associative thoughts from one’s life, has not enough retrieval abilities, and seems not to be able to elicit consciousness.
Last Updated ( Tuesday, 03 April 2007 09:43 )