On 31 Dec 2010 at 12:26, DeVolder Carol L wrote: > My son told me about this site. Maybe I'm the last person to discover it, but > I thought I'd share it just in > case. It seems to be a useful resource. So far I've only looked at the > anatomy of a neuron and > sodium-potassium pumps. I'd be interested in others' opinions. > > http://www.khanacademy.org/
I'm mightily impressed. It's an staggering body of work for one person to create, and he seems to be a gifted teacher. PBS, among others, has taken note of his contribution, and if PBS (The USA television equivalent of the BBC) cares, it must be important (Allen Esterson would disagree about PBS, but that's another story). (See http://tinyurl.com/27qo5mr for the PBS report on Khan). It also seems to me to be revolutionary, opening up high school and university-level tutoring to millions who are without easy access to such education. As the truly cheap laptop becomes a reality and is made available around the world, all any bright third-world person would need is one of those, and the url to Khan's academy. How many more potential Ramanujans are out there who could be kick-started with something like this? I checked out the "anatomy of a neuron" lesson, expecting the standard misconception about this topic. I thought my fear about to comfirmed when he used as his drawn example a motoneuron. I was instead pleasantly surprised. He did not define a dendrite according to the incorrect but widely- used definition as the part of the neuron which conducts a signal _towards_ the soma. Instead, he defined it correctly as the part of the neuron which _receives_ a signal, a definition first advcated by Bodian in a classic paper in _Science_. The problem with the standard incorrect definition is that it only works out for one type of neuron--the motoneuron--and leads to contradictions when applied to others, notably the myelinated bipolar neuron. Focusing on direction of travel in relation to the soma is also of no physiological significance, while a definition in terms of receiving and sending information is. He might have said a bit more about these definitions, perhaps noted that the myelin is provided by oligodendrocytes, not Schwann cells, in the CNS, and given some examples of other types of neuron. But within the limits of the short lesson on YouTube which he set himself, it's a pretty good presentation. Bravo, Sal Khan! And thank you, Carol, for pointing it out. As for Miguel's post asking about the Lin theory of the sodium pump. I haven't heard anything about this, and a Google search seems to turn up mostly Lin himself promoting his work. One exception I found is a 1985 (or so) book review in _New Scientist_ by a chemist, who calls Lin's work "soft science", but says it's still good to have such dissenters. The topic is too difficult for me to evaluate. However, given the great acceptance of the sodium-potassium pump idea, its evident success in understanding and predicting neuronal function, and the total absence of Lin's claims in textbooks, I'd be very cautious about Lin. It sounds to me as though it could be another case of an off-the-wall dissenter, such as Peter Duesberg, who claims that HIV doesn't cause AIDS. Stephen -------------------------------------------- Stephen L. Black, Ph.D. Professor of Psychology, Emeritus Bishop's University Sherbrooke, Quebec, Canada e-mail: sblack at ubishops.ca --------------------------------------------- --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=7584 or send a blank email to leave-7584-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
