This document discusses diversity in synaptic signaling between cortical neurons. It covers different types of synapses, including electrical synapses (gap junctions) and chemical synapses, which release neurotransmitters. The document also discusses the calcium hypothesis, which proposes that inward movement of calcium ions is essential for the electro-secretory coupling process at axon terminals during neurotransmission. Short-term plasticity is also covered, noting it depends on both pre- and post-synaptic mechanisms and the residual calcium hypothesis helps explain facilitation.

1. Diversity of synaptic signaling among individual cortical neurons Synapses are points of contact between nerve cells and their targets where presynaptic signals are converted into postsynaptic signals Electrical synapses (gap junctions) ) • Direct (ionotropic receptors) • Indirect (metabotropic receptors)

12. Fundamental Neuroscience - second edition Squire, Bloom, McConnell, Roberts, Spitzer, Zigmond Academic Press, 2003 http://faculty.washington.edu/chudler/neurok.html http://faculty.washington.edu/chudler/chnt1.html Explore the Brain and Spinal Cord The Neuron http://www.indstate.edu/thcme/mwking/home.html http://www.indstate.edu/thcme/mwking/nerves.html

13. Life cycle of a neurotransmitter

14. The process of chemical neurotransmission can be divided into five steps 1. Synthesis of the neurotransmitter in the presynaptic neuron 2. Storage of the neurotransmitter and/or its precursor in the presynaptic nerve terminal 3. Release of the neurotransmitter into the synaptic cleft 4. Binding and recognition of the neurotransmitter by target receptors 5. Termination of the action of the released transmitter

15. Axon Terminal Spine Dendrite Action potential Ca2+ Diffusion of Neurotransmitters Across the Synaptic Cleft Neurotransmitter Mobilization and Release Electrical Trigger for Neurotransmission

16. The synapse

17. Passing information between neurons Gap junctions -electrical transmission fast both directions Chemical transmission slower - unidirectional integrative amplifies and regenerates the signal

18. Chemical synapse Axon-dendrite Axo-axonic Axon-soma