Birdsong Studies Lead To a Revolution In Biology 117
Smithsonian.com covers research that began with the study of birdsong and ended by overturning the common belief that adult animals can't produce new brain cells. "Deconstructing birdsong may seem an unlikely way to shake up biology. But [Fernando] Nottebohm's research has shattered the belief that a brain gets its quota of nerve cells shortly after birth and stands by helplessly as one by one they die — a 'fact' drummed into every schoolkid's skull. [Nottebohm] demonstrated two decades ago that the brain of a male songbird grows fresh nerve cells in the fall to replace those that die off in summer. The findings were shocking, and scientists voiced skepticism that the adult human brain had the same knack for regeneration. ... Yet, inspired by Nottebohm's work, researchers went on to find that other adult animals — including human beings — are indeed capable of producing new brain cells. And in February, scientists reported for the first time that brand-new nerves in adult mouse brains appeared to conduct impulses — a finding that addressed lingering concerns that newly formed adult neurons might not function."
fat cells and muscle cells, too? (Score:4, Informative)
I learned that nerve, fat, and muscle cells didn't change in number during life*. Seems that's not true about neurons. Apparently also not true about fat cells [wikipedia.org] ("If excess weight is gained as an adult, fat cells increase in size about fourfold before dividing and increasing the absolute number of fat cells present.") Anyone know the scoop on muscle cells?
* - Supposedly weight gain was due to the individual adipocytes getting larger, like a microcosmic obesity. And strength gain was due to more actin and myocin in each myocyte, like a micrcosmic bodybuilder.
Re:fat cells and muscle cells, too? (Score:5, Informative)
I don't know where you studied, but as far as I know, you create tiny rips in your muscles when you work out and new cells are grown to bridge the tear.
Re:fat cells and muscle cells, too? (Score:5, Informative)
No. That it outdated knowledge and is actually an overworking of your muscles. I know that it's stated again, and again, and again, by people who seem to be experts by all standards. Yet there is proper proof that it's not the right way to get stronger, and actually creates scar tissue. So you might get bigger muscles, but not really stronger ones! The strength comes from the tissue that did *not* rupture,and was allowed to grow.
So it's better to lift a lighter weight more often, than a heavier one just a couple of times.
Utter bullshit (Score:3, Informative)
Take a june bug, large and green...tie a string to it's leg and let him fly in circles. At the point where he starts to BLUR, that must be the speed of light. Figure the scale based on RPMs, etc the usual way.
SO: Speed of light: 34 mph!
Seriously: this standard stood for something like 700 years. Science: imperfect.
Wikipedia: Speed of light, history [wikipedia.org]
Physics.virginua.edu: Speed of light [virginia.edu]
Worsleyschool: Measuring the speed of light [worsleyschool.net]
Early, scientific attempts to measure speed of light were very... Well... scientific. And quite accurate. In 1021 an Iraqi physicist realized that light has finite, variable speed that is slower in denser bodies.
In 1629-1667 there were several tries to measure how long it takes for light to move two miles. They all however got to the conclusion that it couldn't be measured because light's speed was so high and human reaction speed could not keep up
In late 1600s astronomers tried to find out the speed of light by observing the moons of Jupiter. They finally got pretty close to the actual value.
Re:Well, duh. (Score:4, Informative)
I don't mean "duh" to the researcher -- obviously things must be tested and validated in the real world, not just postulated -- but it never made sense to me in the first place that brain cells can't regenerate. Why the hell not? What is the adaptive purpose of such a limitation? The brain consumes a huge amount of energy, much more so per-pound than any other organ in the body. That seems to imply that the brain is extremely important to the organism. Why would essentially the most important organ in the body have such a stupid limitation that it can't even recover from MINOR damage? That makes no sense.
One possible explanation for the very limited growth rate of brain cells is that if this growth rate were not tightly controlled, it could lead to "chaotic" brain tissue which could interfere with normal brain function. So general division of brain cells would not be desirable -- but I'm no neuroscientist.
I am, and you're right in nearly every detail. I'd only add:
- New growth would consume energy that the very hungry brain would prefer not to waste that way.
- Brain function develops by strengthening some of its connections, but losing far more. You're born with 4 times the connections you die with. There's no need for new cells in terms of function.
- It actually is in repair that 'chaotic' growth occurs. Neurons are notoriously stupid when it comes to regrowing back in the same place. Severed nerve trunks try to grow back together but get tangled and miss connection, make incorrect connections, or simply turn back on themselves in a tangled "stump neuroma". Some (but not all) of this occurs because the 'interneurons' that act as the telephone poles to the neural wires also get damaged and/or die.
- There's good progress made in getting neurons to regrow and reattach properly, using techniques of treating the cut nerves with certain things and/or using host stem cells. I'm not fully up on the details, but I will be once I read a copy of my son's dissertation; he defended it last month and is just finishing the revisions. I do know that in some cases even severed spinal cords could grow back correctly enough for partial function if treated soon enough with a particular substance. That substance is a common food additive, so phase 1 clinical trials might be skipped. The hope is an injectable treatment would be available to emergency workers which, if the testing bears out the initial studies, would give people with severed nerves more than half their original function in more than half the cases.