Postsynaptic potentials Depending on the type of ion channel which opens, the postsynaptic cell membrane becomes either depolarized or hyperpolarized. Ions will tend to follow the concentration gradient from high to low concentration, and the electrostatic gradient towards the opposite charge.
Excitatory postsynaptic potentials (EPSPs) Opening of ion channels which leads to depolarization makes an action potential more likely, hence “excitatory PSPs”: EPSPs. - Inside of post-synaptic cell becomes less negative.
- Na+ channels (NB remember the action potential)
- Ca2+ . (Also activates structural intracellular changes -> learning.)
Inhibitory postsynaptic potentials (IPSPs) Opening of ion channels which leads to hyperpolarization makes an action potential less likely, hence “inhibitory PSPs”: IPSPs. - Inside of post-synaptic cell becomes more negative.
- K+ (NB remember termination of the action potential)
- Cl- (if already depolarized)
Postsynaptic Ion motion
Neuronal firing: the action potential The action potential is a rapid depolarization of the membrane. It starts at the axon hillock and passes quickly along the axon. The membrane is quickly repolarized to allow subsequent firing.
Requirements at the synapse For the synapse to work properly, six basic events need to happen: Production of the Neurotransmitters Storage of Neurotransmitters Release of Neurotransmitters Binding of Neurotransmitters Generation of a New Action Potential Removal of Neurotransmitters from the Synapse
Three Nobel Prize Winners on Synaptic Transmission
Overview Course introduction Neural Processing: Basic Issues Neural Communication: Basics Vision, Motor Control: Models
Reflex Circuits - Usually Brain-stem, spinal cord based
- Interneurons control reflex behavior
- Central Pattern Generators
Hierarchical Organization of Motor System Primary Motor Cortex and Premotor Areas
Vision and Action
F5 mirror neurons
Vision
Overview of the Visual System
How They Fire No stimuli: Stimuli in center: - ON-center-OFF-surround fires rapidly
- OFF-center-ON-surround doesn’t fire
Stimuli in surround: - OFF-center-ON-surround fires rapidly
- ON-center-OFF-surround doesn’t fire
Stimuli in both regions:
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