[Oo] - Pétage de plomb en direct !!! ::;
Posté : mar. mai 22, 2007 10:37 pm
Voilà ce qui arrive quand mon directeur de labo se met à fondre boulon après boulon ! Moi j'ai qu'un mot : WONDERFUL !!!!
Voilà la copie exact du mail envoyé à l'ensemble de mon laboratoire :
Cher's amis,
Pour célébrer la sortie prochaine du dernier livre de JK Rowling, je viens d'écrire ce texte sur Lord Voldemort. Vos critiques sont les bienvenues car j'essaierai ensuite de faire publier ceci dans un bon journal scientifique.
Lord Voldemort, Dark Energy and Selfish Brain
A tribute to JK Rowlings and Harry Potter
In the past few years, neuroscientists have rediscovered that brain’s energy consumption is enormous, 20% of our resources are dissipated by the brain, although it represents only 2% of our body mass. This high metabolism rate is not driven by conscious tasks. Recent works with functional imaging based on brain oxygen consumption have revealed that less than 1% of brain metabolism in the brain energy budget is accounted for by responses to external stimuli. Thinking, meditating, day dreaming or controlling various motor tasks are not more demanding.
Brain is totally different from most common organs; a muscle, if not in use will get very little blood perfusion and almost no energy consumption. It seems that most of the energy used by the brain is constantly dissipated simply to sustain its existence. High energy demand never stops as the brain has little directly usable energy in reserve ; indeed in the state of life threatening shock, most of the work of the resuscitation team would be first to protect cerebral perfusion if not irremediable brain damages will occur.
This high brain metabolism is puzzling and last year Marcus Raichle (Washington University St Louis) has compared the high energy consumed by the brain to dark energy, a cosmological term. Cosmology could lead to the imaginary world of Harry Potter whose seventh and presumably last book is awaited eagerly this July by millions of muggles. Let us enter in this fantasy world with wizards, witches and wands.
The fantasy world of JK Rowlings has many interesting features to learn for all of us. Harry Potter lives already in a sustainable world with no threat of global warming. In Potter’s world attending scientific meetings and flying overseas do not increase atmospheric CO2, teleportation is the answer. The Time-turner, a trick used by Hermione Granger for attending multiple classes could now be used by our heads of state; they could go back in time and wisely intercedes to avoid the present war in Irak and other conflicts. Time-turner, an archetype in wizard’s world, is in high demand for politicians, but also for every one of us in order to fulfil the promises of our overbooked agendas. It would be good to be able to be at several places at once…
Rowling in her fictional world has the answer for the dark energy of the brain, the culprit is Lord Voldemort. When the Dark Lord Voldemort tried to murder the infant Harry Potter, his mother Lily Potter sacrificed herself to save her son. This act of motherly love protects Harry and reverberates the killing curse on Lord Voldemort himself. The Dark Lord is disembodied and barely survives in a reduced form; without real body he is forced to get in the brain of someone. In the stories, after exhausting several hosts, Lord Voldemort finally ends in the brain of professor Quirrell, becoming a Janus head; one part contains the original brain of professor Quirrell, the other is a selfish brain, the only part surviving of Lord Voldemort. This selfish brain consumes dark energy to accomplish tasks unknown to the conscience of his host. Selfish brains live in good intelligence with their host body and to show good intelligence, selfish brains perform the tasks asked for by their host bodies, good enough these tasks are consuming little of the brain energy budget.
Coming back in a non-fictional world, the question is still on top of our head : why is the brain consuming so much energy ? A simple answer : it does so only to exist and to fulfil its missions. The main function of our brain is to anticipate and to adapt rapidly our actions to changes in the environment. It does it with ease mainly because the human brain is plastic. In thermodynamic terms, plasticity could be viewed as provoking high entropy and disorder. Plasticity should not end in disorder and the adapting brain should remain a very organized tissue, order is a task very demanding in energy. The high energy consumption (enthalpy) is used to permanently construct new contacts, stabilize existing one (Hebb’s synapse), preserving the functional anatomy by firing action potentials through multi-synaptic pathways, never stopping to consolidate past experience in the form of an addressable memory and more... The analogy with supercomputers is an easy one, computers are consuming the same amount of electrical power if they perform tasks or at idle; surely when the power is inadvertently shut down, it is difficult to put it back in action, the same is true for the human brain!
Further reading
Reichle, M.E., The brains’s dark energy. Science, 314, 1249-1250, (2006)
Voilà la copie exact du mail envoyé à l'ensemble de mon laboratoire :
Cher's amis,
Pour célébrer la sortie prochaine du dernier livre de JK Rowling, je viens d'écrire ce texte sur Lord Voldemort. Vos critiques sont les bienvenues car j'essaierai ensuite de faire publier ceci dans un bon journal scientifique.
Lord Voldemort, Dark Energy and Selfish Brain
A tribute to JK Rowlings and Harry Potter
In the past few years, neuroscientists have rediscovered that brain’s energy consumption is enormous, 20% of our resources are dissipated by the brain, although it represents only 2% of our body mass. This high metabolism rate is not driven by conscious tasks. Recent works with functional imaging based on brain oxygen consumption have revealed that less than 1% of brain metabolism in the brain energy budget is accounted for by responses to external stimuli. Thinking, meditating, day dreaming or controlling various motor tasks are not more demanding.
Brain is totally different from most common organs; a muscle, if not in use will get very little blood perfusion and almost no energy consumption. It seems that most of the energy used by the brain is constantly dissipated simply to sustain its existence. High energy demand never stops as the brain has little directly usable energy in reserve ; indeed in the state of life threatening shock, most of the work of the resuscitation team would be first to protect cerebral perfusion if not irremediable brain damages will occur.
This high brain metabolism is puzzling and last year Marcus Raichle (Washington University St Louis) has compared the high energy consumed by the brain to dark energy, a cosmological term. Cosmology could lead to the imaginary world of Harry Potter whose seventh and presumably last book is awaited eagerly this July by millions of muggles. Let us enter in this fantasy world with wizards, witches and wands.
The fantasy world of JK Rowlings has many interesting features to learn for all of us. Harry Potter lives already in a sustainable world with no threat of global warming. In Potter’s world attending scientific meetings and flying overseas do not increase atmospheric CO2, teleportation is the answer. The Time-turner, a trick used by Hermione Granger for attending multiple classes could now be used by our heads of state; they could go back in time and wisely intercedes to avoid the present war in Irak and other conflicts. Time-turner, an archetype in wizard’s world, is in high demand for politicians, but also for every one of us in order to fulfil the promises of our overbooked agendas. It would be good to be able to be at several places at once…
Rowling in her fictional world has the answer for the dark energy of the brain, the culprit is Lord Voldemort. When the Dark Lord Voldemort tried to murder the infant Harry Potter, his mother Lily Potter sacrificed herself to save her son. This act of motherly love protects Harry and reverberates the killing curse on Lord Voldemort himself. The Dark Lord is disembodied and barely survives in a reduced form; without real body he is forced to get in the brain of someone. In the stories, after exhausting several hosts, Lord Voldemort finally ends in the brain of professor Quirrell, becoming a Janus head; one part contains the original brain of professor Quirrell, the other is a selfish brain, the only part surviving of Lord Voldemort. This selfish brain consumes dark energy to accomplish tasks unknown to the conscience of his host. Selfish brains live in good intelligence with their host body and to show good intelligence, selfish brains perform the tasks asked for by their host bodies, good enough these tasks are consuming little of the brain energy budget.
Coming back in a non-fictional world, the question is still on top of our head : why is the brain consuming so much energy ? A simple answer : it does so only to exist and to fulfil its missions. The main function of our brain is to anticipate and to adapt rapidly our actions to changes in the environment. It does it with ease mainly because the human brain is plastic. In thermodynamic terms, plasticity could be viewed as provoking high entropy and disorder. Plasticity should not end in disorder and the adapting brain should remain a very organized tissue, order is a task very demanding in energy. The high energy consumption (enthalpy) is used to permanently construct new contacts, stabilize existing one (Hebb’s synapse), preserving the functional anatomy by firing action potentials through multi-synaptic pathways, never stopping to consolidate past experience in the form of an addressable memory and more... The analogy with supercomputers is an easy one, computers are consuming the same amount of electrical power if they perform tasks or at idle; surely when the power is inadvertently shut down, it is difficult to put it back in action, the same is true for the human brain!
Further reading
Reichle, M.E., The brains’s dark energy. Science, 314, 1249-1250, (2006)