Chapter 13

What are the functional advantages and disadvantages of electrical synapses?

What adaptive advantage do synapses provide in nervous systems (i.e., why isn't the nervous system just a mesh of cells cytoplasmically connected through gap junctions)?

Why is it difficult to show vesicular release of neurotransmitter molecules by electron microscopy?

In his book Ionic Channels of Excitable Membranes, Bertil Hille characterized the importance of calcium ions: "Calcium channels ... serve as the only link to transduce depolarization into all the nonelectrical activities controlled by excitation. Without \(\mathrm{Ca}^{2+}\) channels our nervous system would have no outputs." Discuss this statement with reference to synaptic function.

What are the criteria for identification of the neurotransmitter at a particular synapse? Which two criteria are sufficient to conclude that a candidate is the neurotransmitter?

Why (in evolutionary terms) do you think there are so many kinds of neurotransmitters?

Why are there multiple receptor subtypes for each neurotransmitter? Why not a few receptors and lots of neurotransmitters acting on each receptor?

Discuss the functional differences between ionotropic and metabotropic receptors.

Would you classify NMDA receptors as ionotropic or metabotropic? Why?

Do you think there is one cellular mechanism of learning and memory or several? Cite studies in Aplysia and in the mammalian hippocampus to support your answer.