Molecular basis of learning and memory

[Glutamate]

Hi, I am an undergraduate student of psychology and happen to have some question in regard to this subject. The question are related to the book "Neuroscience: exploring the brain" by Bear, Paradiso... I would not just appreciate answers, but also links to websites or sources, where I can find the answers myself. Thanks.

1. Why does the closing of the H⁺ channel of the aplysia californica prolongate the action potential?

Explanation: The gill-withdrawal reflex in this animal is caused by a simple sensory neuron - motor neuron (L7) connection. If an electric shock is applied to the head of the animal, it gets sensitized, hence making the reflex even stronger.

On the molecular level this means: the axon of the sensory neuron gets depolarized, Ca⁺² channels open and calcium causes the neurotransmitter glutamate to release. (normal reflex)

The sensitization is caused by another neuron (L29) which makes an axoaxonic connection to the axon of the previously mentioned sensory neuron. It uses the neurotransmitter 5-HT (serotonin), which stimulates a g-protein coupled receptor that activates adenylyl cyclase, which produces cAMP. cAMP activates protein kinase A, which phosphorylates a potassium channel.

How and why does phosphorylation cause the channel to close and why does this lead to the prolongation of the presynaptic action potential?

[bill]

can any one give me an idea of how do humans retrieve things from brain and how can we recollect things which we learned from brain, is there a particular mechanism or flow of potential?