BIO2A03-2011-L23 - B iology 2A03 2009 L ect ur e 23 T he tr...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Biology 2A03 - 2009 Lecture 23
Background image of page 1

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

View Full DocumentRight Arrow Icon
The “traditional view” was that n/ t release followed the all-or-none law - that one A.P. always released the same amount of n/ t, and thereby created the same size G.P. at post-synaptic membrane. We now know this is over-simplistic ==> many exceptions: - autoreceptors on pre-synaptic membrane may down-regulate subsequent n/ t release. - multiple transmissions may temporarily exhaust synaptic vesicles of n/ t. - desensitization or loss of post-synaptic receptor proteins may occur in response to multiple transmissions. - upregulation of n/ t release and/ or post-synaptic receptor density may occur in frequently used or rarely used (!) pathways . - presynaptic inhibition or facilitation of n/ t release may occur via axo-axonic synapses . ===> frequency code is greatly modified at chemical synapses
Background image of page 2
Transmissions at axo-axonic synapses may modify n/ t release Presynaptic inhibition
Background image of page 3

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

View Full DocumentRight Arrow Icon
The “traditional view” that synapses followed the All-or-None Law arose because all the early research on synapses was done on one of the largest synapses – the neuromuscular junction - where this is true (Fatt, Katz, & Miledi - Nobel Prize). Chemical synapse between
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/12/2011 for the course BIOL 2A03 taught by Professor Mccelland&dej during the Winter '11 term at McMaster University.

Page1 / 12

BIO2A03-2011-L23 - B iology 2A03 2009 L ect ur e 23 T he tr...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online