Why 18 year olds can't think
Posted: Tue Apr 15, 2008 2:08 am
Well Rydi, I finally found the anatomical basis for why you hate 18 year olds. I recall we had a conversation about people younger than about 23, I still agree and now here comes the science!
Two essential components of neuroscience are needed to explain the observed phenomena.
Firstly, Myelin. A neuron has exactly one axon, which is a long process that extends and synapses upon another neuron, and it is down this axon that action potentials are conducted and forms the anatomical basis for the 'circuitry' that neuron complexes demonstrate. Each axon is surrounded by a sheath called myelin, which accelerates the action potential transmission. "slow" axons, that are un-myelinated, have been clocked no faster than 30 meters/second, and as slow as less than 1 meter per second. This seems fast, but 'fast' axons, with a myelin sheath, conduct as fast as 120 meters/second, and usually no slower than 100 meters/second. Now, this affects a great many things, action potentials must accumulate on a target neuron in order for the target neuron to fire its action potential, and you can see how a great many excitatory and inhibitory neurons all interconnected could propagate action potentials and, in a complex enough system, form the basis for storage, retrieval, and processing of information. Recall that in multiple sclerosis the pathophysiology is 'demyelination'.
Second, association cortex. For every sense the body has, as well as emotion, there is an association cortex. We have seen demonstrated through studies of lesions in living people that these areas are where 'higher order' though takes place, and stimuli are correlated here with emotion. Humans have vastly more association cortex in their brains than any other living creature, even dolphins, and we think this is why we have rocketships and they don't. Memory seems to be stored in the association cortex, as well as the emotional connotations of those memories.
Now that that's out of the way, I can reveal that until the third decade of life, the association cortex does not finish myelination. That's right. 30. So, the anatomical basis for processing of information balanced with emotion and memory does not reach it's most ideal configuration until somewhere in the mid to late 20s.
In the absence of myelin, these neurons would still transmit their pulses, but the pulses would fade out before enough pulses accumulated to cause the desired response. So, it takes more to do the same, which generally means you get less.
/end science.
Two essential components of neuroscience are needed to explain the observed phenomena.
Firstly, Myelin. A neuron has exactly one axon, which is a long process that extends and synapses upon another neuron, and it is down this axon that action potentials are conducted and forms the anatomical basis for the 'circuitry' that neuron complexes demonstrate. Each axon is surrounded by a sheath called myelin, which accelerates the action potential transmission. "slow" axons, that are un-myelinated, have been clocked no faster than 30 meters/second, and as slow as less than 1 meter per second. This seems fast, but 'fast' axons, with a myelin sheath, conduct as fast as 120 meters/second, and usually no slower than 100 meters/second. Now, this affects a great many things, action potentials must accumulate on a target neuron in order for the target neuron to fire its action potential, and you can see how a great many excitatory and inhibitory neurons all interconnected could propagate action potentials and, in a complex enough system, form the basis for storage, retrieval, and processing of information. Recall that in multiple sclerosis the pathophysiology is 'demyelination'.
Second, association cortex. For every sense the body has, as well as emotion, there is an association cortex. We have seen demonstrated through studies of lesions in living people that these areas are where 'higher order' though takes place, and stimuli are correlated here with emotion. Humans have vastly more association cortex in their brains than any other living creature, even dolphins, and we think this is why we have rocketships and they don't. Memory seems to be stored in the association cortex, as well as the emotional connotations of those memories.
Now that that's out of the way, I can reveal that until the third decade of life, the association cortex does not finish myelination. That's right. 30. So, the anatomical basis for processing of information balanced with emotion and memory does not reach it's most ideal configuration until somewhere in the mid to late 20s.
In the absence of myelin, these neurons would still transmit their pulses, but the pulses would fade out before enough pulses accumulated to cause the desired response. So, it takes more to do the same, which generally means you get less.
/end science.