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Please forgive me if I make some corrections. Sorry, but I'm a neurobiologist, and I'm handicapped by my blind obsession with factual details. ;) "The synaptic gap is excited, once, twice, three times, each time sending out one type of neurotransmitter. But if you really excite that next neuron over and over finally it releases a different kind of neurotransmitter..." The presynaptic neuron does not change the neurotransmitter it releases during LTP. It continues releasing the SAME neurotransmitter, which is glutamate. The postsynaptic neuron, however, has two different RECEPTORS for glutamate. One type, AMPA receptors, open when the postsynaptic neuron is weakly stimulation (depolarized). The second type, NMDA receptors, open when the neuron is strongly stimulated. Yes, I know the name of the receptors are confusing. You would think an "NMDA receptor" would normally be looking for an NMDA molecule rather than a glutamate molecule. The receptor types are named for molecules that mimic the effects of glutamate. The relationship between LTP and learning is complicated. LTP was discovered in 1973, but there weren't clear demonstrations it was involved in learning until about 2006. And there are some regions of the brain that show LTP, but use completely different mechanisms than described here; no NMDA receptors are involved. It's a VERY long reach to say, "LTP explains how people get ideas fixed in their minds." In studies in the lab, LTP can lasts for hours, or days, sometimes weeks, but it isn't necessarily permanent. Plus, there is not only LTP, but LTD (long term depression -- not depression = sad, but depression = less postsynaptic response), too. Nervous systems have to be forget as well as remember.
My inclination is to flip the axes. I think we grasp "more" vs. "less" more readily along the horizontal axis than the vertical.
Toggle Commented Nov 17, 2009 on Disentangle at Junk Charts