Archive for the ‘Neuroscience’ Category

Agency and reward

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This paper can be taken as suggesting that a sense of agency is part of the reward system, encouraging repetition or non-repetition of particular actions or behaviours.

Ventromedial and confidence

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The ventromedial prefrontal cortex is the brain region most associated with ratings of the relative value of stimuli. Subjects are seen as assigning subjective values to the potential outcomes of possible actions leading to valuable results.

Libet v. recent neuroscience

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A source of despair in consciousness studies is the way in which popular science writers continue to plough ahead making pronouncements that are flatly contradicted by the neuroscientific data of recent years. In particular, consciousness students might be forgiven for screaming every time Libet’s veteran 1980s experiment is trundled out. Halligan and Oakley writing in a recent issue of ‘New Scientist’ go down this predictable route. The brain prepares for actions such as reaching out prior to awareness of the intention to reach.

Mitochondria ion channels

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The primary function of mitochondria is to generate ATP that supplies cells with energy. Mitochondria are cell organelles comprising an outer and inner membrane, the latter enclosing a matrix space in which hydrogen and electrons are extracted. The inner membrane contains the respiratory chain; the energy from oxidation/reduction reactions is used to move protons out of the inner matrix and across the inner membrane. This establishes an electrochemical potential gradient across the membrane which allows the synthesize of ATP from ADP.

Dynamic causal modelling

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Dynamic causal modelling (DCM) was created in order to estimate the functioning of connections between different brain regions. DCM infers the causal structure of distributed systems. It uses a Bayesian system to study how current data was created.

Dorsal and ventral attention

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Macaque monkeys are often used as models in neuroscience. However, there are important differences between macaques and humans. Humans have a larger dorsal attention network, indicating that evolution has augmented this network. Biases in visual searches are different as between the two species, and

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.

Orbitofrontal cortex

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The paper focuses mainly on the lateral orbitofrontal. Orbitofrontal damage can lead to difficulties in switching from behaviours that were previously advantageous, but have ceased to be so. However, the ability to make an initial discrimination, as opposed to altering an existing one, is usually unaffected. Nevertheless, changes in response are not seen as a core function of the orbitofrontal, and damage to the orbitofrontal is seen to effect a range of other tasks.

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 […]