Download LTP

LTP - Long-Term Potentiation (Lomo,1966)
Learning » experience (conditioning, thinking) changes the CNS
(permanently?) and therefore behavior.
Hebb Rule : when synapse is repeatedly active as the post-synaptic
neuron fires, this synapse becomes strengthened.
“Airpuff”
strong synapse
CC or Associative LTP
“Blink”
“Tone”
weak synapse
post-synaptic neuron
Pinel
Text
NMDA - Receptor (N-methyl-D-Aspartate)
Transmitter: Glutamate
(a)Transmitter + (b)voltage-gated receptor
Glutamate
Post-synaptic depolarization » ejects magnesium
block from calcium channel » glutamate opens
channel » calcium enters post-synaptic cell.
» Ca++ » enzymes: protein kinases (3?) » change non-NMDA
(AMPA?) glutamate receptors; enzymes also produce nitric
oxide (NO), a retrograde messenger (back to presynaptic
terminal) releasing more glutamate (?)
See diagram
Structural Changes?
A) more post-synaptic receptors (AMPA, Glutamate)
B) more transmitter (Glutamate) release
C) growth of more terminal buttons (pre-synaptic)
D) thicker dendritic spines » easier to depolarize (e.g., EPSP)
Long-term Depression (LTD): “undo LTP”
Low-frequency stimulation (< 10 Hz)
Extinction?
NMDA receptor blocker - AP5 (amino phosphono valeric acid)
**AP5 interferes with learning
Reinforcement: DA & Enkephalins
(DA antagonists, Naloxone block LTP)
Review of cascade in LTP
1. Post-synaptic depolarization » magnesium blocked removed
2. Glutamate-binding » Ca ++ enters cell
3. Ca++ » protein kinases
4. Functional and structural changes :
A)
increases non-NMDA receptors (AMPA)
B) changes shape of spines
C)
D)
NO » Glutamate release increased
sprouting buttons increased
A & B are post-synaptic and C & D are pre-synaptic
4D
1
2
4B
3
4A
4C
Associative LTP
CER » amygdala (LeDoux, 2000)
shock
“strong”
Response (CER)
a) autonomic (heart)
b) skeletal (freeze)
tone
“weak”
230 Final Exam (3 hrs)
Ch. 11-15, 17 (100 multiple-choice, 50%)
Essay topics: Learning/memory
Emotion/stress
( 2 of 3 essays, 50%)