In article <395BA0E9.E12EC8BF at nospam.com>, rh <rh at nospam.com> writes:
>>As I understand it, as neural pathways are used
>the spines grow and become more numerous.
>>My question is: why? Why do they get bigger? Also, do they multiply,
>or are they just changing shape?....what accounts for this new form that
>they take?
>>Thanks.
I am not an expert, but think that this is caused by 'retrograde messengers'.
When a neurotransmitter conveys a message accross a synapse, the neuron on the
receiving end sends back a reply in the form of a retrograde messenger. For
example the gas NO is a type of retrograde messenger. It has a very short life,
and when it is released from the post-synaptic membrane, itdiffuses into the
surrounding area. The more activity there is at the synapse, the more NO is
released. The NO also acts as a' nerve growth factor' , and the more there
is, the more it stimulates the growth of new branches from nearby neurons.
That is the way I understand it.
Tony