Long-Term Potentiation (LTP) Flashcards Preview

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Flashcards in Long-Term Potentiation (LTP) Deck (16):
1

Long-Term Potentiation (LTP)

(Semi-)permanent structural and connectivity changes, via variety of mechanisms

physical change in the circuitry responsible for learning changes

neurological definition of learning

2

Post-Synaptic

(P.S.)

Include structural changes in Receptor Sites, Dendritization, etc.

3

e.g. Hippocampus in the Rat, in which the best-studied mechanisms of LTP involve…

(P.S.)

- Cells w/multiple types of Glutamate Receptor Sites on the same cell; Some sites harder to trigger than others

- AMPA Receptor Sites

- NMDA Receptor Sites

- Typically Magnesium ions (Mg++) block these gates that, when opened, allow Na+ & Ca++ to enter

4

AMPA Receptor Sites

(P.S.)

respond well to Glutamate (Ionotroipic: Allow Na+ in to excite Post-Synaptic cell)

5

NMDA Receptor Sites

(P.S.)

only respond to Glutamate if cell already partially hypo-polarized by above

6

Typically Magnesium ions (Mg++)...

(P.S.)

....these gates that, when opened, allow Na+ & Ca++ to enter

7

- When Post-Synaptic cell is massively stimulated by Glutamate from multiple Pre-Synaptic cells…

(P.S.)

- AMPA receptors reduce polarity of cell, evict Mg++, allowing NMDA Receptors to also respond

8

- Ca++ influx helps change structure of Post-Synaptic cell, increasing its future responsiveness to Glutamate

e.g.?


(P.S.)

e.g. New AMPA receptors form, or old ones are made even more responsive

- e.g. Some NMDA Receptors are changed into the easier-to-stimulate AMPA receptors

- e.g. Activates enzymes in cell that break protein “bridges” that structure dendritic spines, splitting them to form new dendritic branches (increased surface area) lined with AMPA Receptors

9

Pre-Synaptic

- Retrograde Messengers (e.g. Nitrous oxide) from Post-Syn cell that prolong NT release

- Perforation

10

Perforation

division, expansion of “Active Zone” of Pre-Syn by out-growth from surface of Post-Synaptic cell

11

Genetic

Activity can turn on transcription of DNA to RNA, then translation of RNA into proteins

- e.g. Such proteins may change #, size, & distribution of NT vesicles, or other relevant metabolic processes in cell

12

Neurogenesis:

Rare in NS overall, but common in Hippocampus, esp re temporal-based and spatial learning

13

Ca++ influx helps change structure of

Post-Synaptic cell, increasing its future responsiveness to Glutamate

14

Retrograde Messengers

released by post-synaptic cell that stimulate pre-synaptic cell, making it easier for connections to form

easier for NT release from pre-synaptic

chemical feedback from post-synaptic cell

15

dendrite increase

their branching

16

terminal buttons

can also multiply