Posts Tagged ‘consciousness’

Altered states of consciousness

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It is argued that altered states, which can result from a range of cause including near-death-experience (NDE), meditation or psychedelic drugs, can be directly causal of durable personality changes. Further to this, recent experimentation suggests that some altered states can deactivate brain regions responsible both for the sense of self, and for constraining ‘mystical’ type experiences in other brain regions. Thus contrary to any suggestion that the self is some type of ‘mystical illusion’ it may in fact be part of a system that constrains ‘mystical’ experience during normal brain processing.

Consciousness as a meta-phenomenon

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The year is 1954.

Alan Turing, is returning home from work at the University of Manchester where he is using the recently installed Ferranti Mark 1 computer to further his researches on morphogenesis and other matters. This behemoth of a machine with 4,000 valves, 2,500 capacitors, 15,000 resistors, 100,000 soldered joints and 6 miles of wire boasts a huge 5120 bit random access CRT memory, 72kbytes of magnetic drum storage and can carry out over 800 additions every second; but for Turing this is not nearly enough. He dreams of the day when a computer can play chess as well as he can and can even fool us into thinking that it might be conscious. After all, isn’t the human brain just a computer with nerves instead of valves?

Implicate order

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Bohm argued that both relativity and quantum theory meant that any analysis of the physical world into distinct, well-defined parts was no longer relevant. He suggests that the structure of holograms gives an insight into his concept of undivided wholeness.

In his description of holograms, coherent light from a laser passes through a half-silvered mirror, with part of the beam falling onto a photographic plate, while the other part illuminates a particular structure. Light reflected from this structure also reaches the plate where it interferes with the light waves arriving from the half-silvered mirror. When this photographic plate is lit by laser light a wave front is created, which is seen to have a similar form to the light coming off the illuminated structure. This allows an observer to see the whole of the structure in three dimensions. If only a small part of the photographic plate is illuminated, the whole structure is still visible although less sharply defined.

Reality, perception, physics

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Thoughts on Reality An insubstantial pageant The one thing we can be reasonably sure of is that what we see has nothing to do with reality. Physics tells us as much as that; that there are no things and there is no colour green. Visual information is delivered to the retina by photons fluctuating at varying frequencies. The photons are either reflected from or produced by ‘objects’, which can in their turn be understood as quantum particles held together by the charges of the electromagnetic Read more […]

Anaesthetics and brain energy

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Brain regions where there is an increase in functional energetic demand have a corresponding increase in glucose metabolism, their metabolic rate for oxygen and their cerebral blood flow. Cerebral energy is seen as depending on the oxidation of glucose. Cerebral blood flow similarly tracks energy consumption.

Conscious perception

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A recent study by Aaron Schurger of the Swiss Federal Institute of Technology suggests that for conscious perception to occur brain activity has to be stabilised for some hundreds of milliseconds. In Schurger’s study, subjects saw a red-on-green line drawing in one eye, but a green-on-red drawing in the other eye.

Brain’s Resting State

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The brain’s resting state activity accounts for about 80% of its energy consumption. Anaesthesia, in which consciousness is removed, involves a 40-50% reduction in energy consumption, implying that part of the resting state’s high level of energy consumption is used to sustain consciousness. The resting state also overlaps with the reward system which is based on midline structures, as distinct from lateral regions that are more involved in planning and reasoning.

Energy and consciousness

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The authors argue that the conscious state is supported by a high and fairly uniform baseline energy consumption and related levels of neural activity. This viewed is based on PET scanning measures of glucose and oxygen consumption, taken with subjects under anaesthesia, that showed that energy levels while under anaesthesia are 40-50% below awake resting levels across different brain regions.

Chalmers on consciousness

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Chalmers asks why it is that we are conscious, and argues that a radical idea is required if we are to arrive at an explanation. Recent research has concentrated on searching for correlates of consciousness, such as brain regions that are active when consciousness is reported. However, such correlates are just things that coincide with consciousness rather than explanations. Emergence has also been seen as an explanation of consciousness, in the sense that hurricanes emerge from particular weather systems, and by analogy, consciousness emerges from neural systems and possibly also computer systems. However, Chalmers sees this as only explaining structure and behaviour rather than consciousness as such.

Patricia Churchland and Neuroscience

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At peace with my brain  Patricia Churchland interviewed by Graham Lawton  ::  New Scientist, 30 November 2013  ::  www.newscientist.com Summary and review of the above interview In this interview, it is apparent that the philosopher, Patricia Churchland, has moved on to occupy the neuroscience territory. As part of the group of 1990s thinkers that directed consciousness towards what some might argue to be its present cul-de-sac, in which sensible people are inhibited about discussing any Read more […]