Ionotropic Receptors Postsynaptic potentials

Ionotropic Receptors

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

• Synaptic vesicles (SV)

• Storage of Neurotransmitters

• SV

• Release of Neurotransmitters

• Binding of Neurotransmitters

• Lock and key

• Generation of a New Action Potential

• Removal of Neurotransmitters from the Synapse

• reuptake

Three Nobel Prize Winners on Synaptic Transmission

Overview

• Course introduction

• Neural Processing: Basic Issues

• Neural Communication: Basics

• Vision, Motor Control: Models

Motor Control Basics

• Reflex Circuits

• Usually Brain-stem, spinal cord based
• Interneurons control reflex behavior
• Central Pattern Generators

• Cortical Control

Hierarchical Organization of Motor System

• Primary Motor Cortex and Premotor Areas

Vision and Action

F5 mirror neurons

Vision

Overview of the Visual System

The Microscopic View

How They Fire

• No stimuli:

• both fire at base rate

• 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:

• both fire slowly