Lecture 8.F10

Lecture 8.F10 - Neuroscience 106: Lecture 8 - Postsynaptic...

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Neuroscience 106: Lecture 8 - Postsynaptic Potentials, Complex PSPs, electrical synapses, and spontaneously active neurons. ANNOUNCEMENTS: 1. Midterm will cover Bear et al., Ch 1, 2, 3, 4, 5, 6 , 7 TODAY'S LECTURE: I. Presynaptic inhibition and facilitation. A. Presynaptic facilitation enhances the release of neurotransmitter from the terminal receiving the presynaptic input. Therefore the EPSP or IPSP in the postsynaptic neuron is increased. Excitatory input from the terminal producing presynaptic facilitation Effect of presynaptic facilitation and inhibition on the AP waveform in the “recipient” terminal . IPSP= PS inhibition EPSP = PS Facilitation AP inside the terminal made longer or higher by presynaptic facilitation. So more neurotransmitter released. AP inside the terminal briefer or smaller by presynaptic inhibition. So less neurotransmitter released. 1
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increases the amplitude and/or duration of the action potential in the recipient terminal. That opens more voltage gated calcium channels, producing an increase in neurotransmitter release from the recipient terminal. B. Presynaptic inhibition decreases (or inhibits) the release of neurotransmitter by the terminal receiving the presynaptic input. Therefore the EPSP or IPSP in the postsynaptic neuron is decreased. Inhibitory input from the presynaptic terminal decreases the amplitude and/or duration of the action potential in the recipient terminal. Because fewer voltage gated calcium are opened, this results in a decrease in neurotransmitter release. C. The utility (or advantage) of axo-axonic synapses resulting in presynaptic inhibition or facilitation is that it is a mechanism for enhancing the specificity of a particular input without affecting the other inputs. Presynaptic inhibition here only affects the PSP produced by one terminal. 2
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II. Electrical synapses A. For review, a key component of chemical synapses is the synaptic vesicle with neurotransmitter. The neurotransmitter is released into the synaptic cleft and binds to receptors in the postsynaptic membrane which results in a postsynaptic potential. There is a 0.2 ms synaptic delay in this process, which is the time between the action potential reaching the terminal to the time of a postsynaptic effect. B. Below is a diagram depicting an electrical synapse
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This note was uploaded on 11/10/2010 for the course CBNS 106 taught by Professor Korzus during the Fall '08 term at UC Riverside.

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Lecture 8.F10 - Neuroscience 106: Lecture 8 - Postsynaptic...

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