ch17.1 - Long term potentiation (LTP)

LTP meaning

long term potentiation

LTP is a

increase in activity of synapses from a specific stimulation

long term potentiation means that the ______ lasts longer

excitatory effect

what happens if you stimulate axons with a low frequency (1Hz)

stable response size in neurons

what happens if you stimulate axons with a high frequency for a brief moment (100Hz)?

higher response that remains for minutes/hours afterwards

LTP was first observed in the ___ but is fundamental to neurons in the entire ____

hippocampus/ CNS

3 hippocampal pathways that display LTP

1. perforant pathway

2. mossy fiber

3. schaffer collaterals

LTP is a physiological mechanism of learning that requires the ____ (which gives it plasticity)

hypothalamus

time of LTP =

time of learning

early stage LTP

short term memory; NO protein synthesis

late stage LTP

long term memory (⬆CREB, makes proteins, ⬆gene expression, stronger synapses)

when you sleep you ___ so that when you wake up you can ____

make proteins/ remember

diagram of LTP stages

step 1 LTP

Na enters through AMPA-R

step 2 LTP

depolarize cell enough that Mg gets kicked out

step 3 LTP

Ca2+ entry (key for kinases activation)

step 4 LTP

Ca2+ activate kinases

step 5 LTP

kinases drive insertion of AMPA-R into synapse

step 6 LTP

kinases activate CREB protein

step 7 LTP

CREB increases protein synthesis

AMPA-R

ionotropic Glu receptors that control excitatory NT

NMDA-R

ionotropic Glu receptor that controls EPSP

why is NMDA unique and VERY important?

permeable both to Na and ALSO CA2+!!! this is huge because Ca2+ basically drives the whole process of LTP

what does driving AMPA-R into synapses do?

the more AMPA-R on post-syn, the more sensitive to glutamate it is!

why is it important for a cell to be sensitive to glutamate?

because it’s the primary excitatory NT, essential for rapid communication, learning and memory!!!

retrograde signals

enhance Glu release in presynaptic terminals

3 kinases

1. PKA

2. PKC

3. CAMKII

what are kinases

enzymes that add phosphate groups to molecules using ATP; drive growth and metabolism; on and off switch

adding phosphate to proteins is a way of

storing energy

kinases will trigger the synthesis of

proteins

CREB

key protein that alters gene expression during LTP

CREB’s journey in LTP stages

gets phosphorylated by kinases, goes into nucleus, binds to DNA and turns genes important for strengthening synapses

early stage takes approximately

1 hour

hippocampal neurogenesis

another mechanism of learning; neurons are generated in dentate gyrus

cells that survive in dentate gyrus after being neurogenerated will become

granule neurons in granule cell layer

3 things that increase neurogenesis

1. exercise

2. experience in environment

3. spatial learning tasks

new neurons are more ___ and have ____ LTP than older ones

plastic/ stronger

learning will _____ survival of neurons generated in hippocampus

enhance!

key term in synaptic strengthening?

plasticity

plasticity may be ___ or ___

functional/ structural

functional plasticity

more NTS, more receptors (reorganization)

structural plasticity

more synapses, more neurons (physical changes to brains wiring)

plasticity ONLY occurs in brian regions that are..

essential for the storage of a certain type of memory