{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

les5_20102008ppt - Synaptic integration Molecular signaling...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 1 Molecular signaling in the neuron General principles of cell signaling Ion channels Membrane potential (resting – action potential) • Synaptic transmission – Electrical – Chemical • NMJ • CNS 2 Synaptic integration Synaptic transmission between neurons at CNS is much more complex than at NMJ: -central neuron receives inputs from hundreds of other neurons -central neuron receives both excitatory and inhibitory signals -central neuron must integrate diverse incoming signals and decide if it will fire an action potential or not Synaptic transmission at NMJ is very efficient barb2right AP in presynaptic cell leads to AP in postsynaptic cell bleftright in CNS individual PSP are way too small (around 0.2 mV) to generate action potential => individual PSP’s are summed to total net PSP that arrives through passive propagation in cell body 3 •Sculpturing role of inhibition (inhibitory synaptic potential) •The effect of a synaptic potential is determined not by the type of transmitter released, but by the type of ion channels gated by the transmitter in the postsynaptic cell: most transmitters are recognized by receptors that mediate either excitatory or inhibitory potentials * neurons that release glutamate : act on receptors that produce excitation * neurons that release GABA or glycine : act on ionotropic inhibitory receptors •Two common morphological types of synaptic connections: Gray type I and II type I synapses: often glutamatergic (excitatory) type II synapses: GABA-ergic (inhibitory) Inhibitory and excitatory neurotransmitters 4 Inhibitory and excitatory neurotransmitters 5 Excitatory synaptic action: glutamate-gated channels (K+ and Na+) 6 Three classes of glutamate receptors conduct both Na + and K + The non-NMDA receptors are important for the early component of the EPSP in motor neurons The NMDA-receptors are important for the late component of the EPSP response and also have a major role in long term potentiation (LTP)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 7 Three classes of glutamate receptors conduct both Na + and K + 8 Three classes of glutamate receptors conduct both Na + and K + 9 Inhibitory synaptic action: GABA- and glycine-gated channels – Cl- GABA binds to ionotropic Cl - channels or metabotropic K + -channels, glycine binds ionotropic Cl - channels the Cl - channels allow Cl - to flow in => hyperpolarisation the K + -channels allow K + to flow out => hyperpolarisation 10 Inhibitory synaptic action: GABA- and glycine-gated channels – Cl- 11 Structure of glutamate, GABA- and glycine-gated channels 12 Postsynaptic protein complex
Background image of page 2
3 13 Postsynaptic protein complex 14 Neuronal integration: introduction A cell at any given moment has two options : to fire or not to fire. This decision-making = the brain’s most fundamental operation Excitatory and inhibitory signals are integrated into a single response by the cell The net effect of the inputs at any individual excitatory or inhibitory synapse will depend on several factors: location, size and shape of the synapse
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}