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The History of Artificial Cerebrospinal Fluid (ACSF)
For the ACSF updates in 2009 to 2011 -> see Sweet & sour recipes for the brain
ACSF from 1934 to 1950.
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1934
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Alexis F. Hartmann developed several solutions for replacement of lost physiological fluids in clinics | The solutions didn’t include glucose but one of them contained 27 mM Na-lactate. This solution is still in clinical use. | Hartmann, A. F. (1934) Theory and practice of parenteral fluid administration. JAMA, J. Am. Med. Assoc., 103, 1349±1354.
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1949
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A modification of one of Hartman’s solutions was developed, mimicking the cerebro-spinal fluid | This solution mimicked natural CSF: 21.7 mM HCO3 was close to 21.1 mM observed in CSF although it contained 4.5 mM glucose, almost 1.5 times higher than in CSF | Elliott, K. A. and Jasper, H. H. (1949) Physiological salt solutions for brain surgery; studies of local pH and pial vessel reactions to buffered and unbuffered isotonic solutions. J Neurosurg, 6, 140-152. |
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1950- current
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The term “artificial cerebrospinal fluid” (ACSF) introduced | ACSF is used in clinics and in experiments on brain slices | Elliott, K. A.and Lewis, R. C. (1950) Clinical uses of an artificial cerebrospinal fluid. J Neurosurg, 7, 256-260. |
Amazingly, but in 1950, the history of ACSF stops and in the neuroscience labs, researchers working with brain slices still use the same ACSF (although since that time, the knowledge about neuronal biochemical needs significantly progressed).
“The natural cerebrospinal fluid (CSF)… attempts to simulate not the milieu surrounding the brain’s cells but rather the more easily accessible (and hence analyzable) fluid in the ventricular system. Recipes for artificial CSF (ACSF) vary, often quite widely, between labs. Moreover, commercially available ‘ACSF’… has a composition that is known to be different from that of the CSF” (E.C. McNay, R.S. Sherwin / Journal of Neuroscience Methods 132 (2004) 35–43).
Amazingly, but in 1950, the history of ACSF stops and in the neuroscience labs, researchers working with brain slices still use the same ACSF (although since that time, the knowledge about neuronal biochemical needs significantly progressed).
“The natural cerebrospinal fluid (CSF)… attempts to simulate not the milieu surrounding the brain’s cells but rather the more easily accessible (and hence analyzable) fluid in the ventricular system. Recipes for artificial CSF (ACSF) vary, often quite widely, between labs. Moreover, commercially available ‘ACSF’… has a composition that is known to be different from that of the CSF” (E.C. McNay, R.S. Sherwin / Journal of Neuroscience Methods 132 (2004) 35–43).
Related reading: Barriers and fluids that connect and divide blood, brain, and neurons
The brain believes the sweet taste rather than metabolic facts
It’s a well known fact that drinking carbohydrate-rich beverages during high-intensity exercise improves performance even if it’s relatively short, which made researchers suspect that direct metabolic effect could hardly be the reason since there’s simply not enough time to digest the carbs and deliver the energy to the muscles. The only alternative seemed to be “all in the brain”. To check this hypothesis, the metabolic input excluded completely: the athletes didn’t swallow the drink but only rinsed the mouth with it – and performance also improved!
Now, the discussion is going on, which brain structures are responsible and how they overrule the chemical senses inside the body that tells the truth: no energy has been ingested, The brain for some reason believe the sense of sweetness rather than the qualitative report from the blood.
Why any sweet taste, coming with any sweetener, raises glucose concentration in the blood *before* the food has a chance to be digested? Because your body knows that eventually, it will have all the carbs you’ve swallowed and it doesn’t wait until it that happens and borrows real carbohydrates from carbohydrate depots. In the case of physical performance, the brain recruits muscles in anticipation of real energy coming into the blood soon, and this always happened in the past, before artificial sweeteners and wicked experimental protocols were invented.
Sources:
Current Opinion in Clinical Nutrition and Metabolic Care 2010, 13
BMJ 2004; 329: 755-756
Response: http://www.bmj.com/cgi/eletters/329/7469/755#78439
It’s a well known fact that drinking carbohydrate-rich beverages during high-intensity exercise improves performance even if it’s relatively short, which made researchers suspect that direct metabolic effect could hardly be the reason since there’s simply not enough time to digest the carbs and deliver the energy to the muscles. The only alternative seemed to be “all in the brain”. To check this hypothesis, the metabolic input excluded completely: the athletes didn’t swallow the drink but only rinsed the mouth with it - and performance also improved!
Now, the discussion is going on, which brain structures are responsible and how they overrule the chemical senses inside the body that tells the truth: no energy has been ingested, The brain for some reason believe the sense of sweetness rather than the qualitative report from the blood.
Why any sweet taste, coming with any sweetener, raises glucose concentration in the blood *before* the food has a chance to be digested? Because your body knows that eventually, it will have all the carbs you’ve swallowed and it doesn’t wait until it that happens and borrows real carbohydrates from carbohydrate depots. In the case of physical performance, the brain recruits muscles in anticipation of real energy coming into the blood soon, and this always happened in the past, before artificial sweeteners and wicked experimental protocols were invented.
Source: Jeukendrup, Chambers. Oral carbohydrate sensing and exercise performance. Current Opinion in Clinical Nutrition and Metabolic Care 2010, 13:447-451
The resting brain is not silent
Is the brain just a vessel, which is empty until the outside world fills it with reflections of its elements? What’s going on inside the calm brain of a quiet person? The current view is that it fluctuates in an organized manner even in in the absence of stimulation. When the brain is being tested, this organized activity interacts with the evoked activity.
Turns out that the same way it influences behavior. Even as simple task as pressing the button is influenced by the internal (intrinsic), which influence is such strong that 74% of fluctuations in the button pressing task attributable to the intrinsic, “introversive” brain activity. This makes us so different and so authentic, this preserves our personalities.
In the book The Man with a Shattered World: The History of a Brain Wound.,” the Soviet psychologist Aleksandr R. Luria (1902-77) describes the life of a young soldier who suffers a catastrophic head injury and profound loss of both short-term and long-term memory, forgot who he was and what were the things around him. Listening to a phrase, he would forget the beginning of it. His image recognition ability was limited to almost nothing. He could, however, recognize a word he “meant” inside himself in the flow of otherwise senseless sounds from the radio and his motor memory for writing was somewhat operative.
So he sat in front of his radio waiting for the only word he needed at the moment to write it down as quickly as possible before it slips out of his memory. What happened after 20 years of this work, was a book — and thank to this book we now know that in the “shuttered world” the brain keeps working, the intact personality inside is reaching out, inventing ways to communicate with the Big World out there. In 1973 one reviewer called the book an intriguing and ‘valuable review of the strange but precise working of the brain.’ Shall we add “precise and intrinsic” working of the brain?
Is the brain just a vessel, which is empty until the outside world fills it with reflections of its elements? What’s going on inside the calm brain of a quiet person? The current view is that it fluctuates in an organized manner even in in the absence of stimulation. When the brain is being tested, this organized activity interacts with the evoked activity. Turns out that the same way it influences behavior. Even as simple task as pressing the button is influenced by the internal (intrinsic), which influence is such strong that 74% of fluctuations in the button pressing task attributable to the intrinsic, “introversive” brain activity. This makes us so different and so authentic, this preserves our personalities. (more…)
