2 - Synaptic Plasticity Flashcards
T/F. The underpinning learning and memory processes, including motor learning and skill acquisition, is believed to reside in the experience-dependent modification of the synapse strength between neurons.
True
T/F. There are fundamental processes that change the strength of the synapse between neurons.
True
Action potential:
How it is generated
How do neurons communicate with each other?
Using short spikes of electrical activity (AP)
How are APs possible?
Cell membranes are semipermeable to ion flow, and voltage-gated channels in the membrane control this permeability
What is the sequence of APs?
1) Cells at rest is permeable primarily to K+ ions, cell near K+ reversal potential (-80mV)
2) Small amount of input current raises cell potential
3) Voltage-gated Na+ channels ope, allowing more Na+ in, and opening more channels
4) Voltage spikes Na+ channels deactivate, and K+ open returning the cell to rest
What is synaptic strength?
Size of the post-synaptic potential
What are post-synaptic potentials?
Change in voltage in the post-synaptic cell caused by a SINGLE spike in the presynaptic cell
What units are post-synaptic potentials are in?
mV
Can post-synaptic potentials be either both positive (excitatory) or negative (inhibitory)?
Yes
EPSP?
Pre-synaptic cell wants to help the post-synaptic cell fire a spike.
IPSP?
Pre-synaptic cell wants to prevent the post-synaptic cell from firing a spike.
Synaptic strength?
Used to store important info in the NS.
The size principle of motor activation?
Motor units come in varying sizes
- Small motor units producing the least amount of force but least susceptible to fatigue
- Larger motor units gets fatigue easier
Synaptic strength is encoded by:
Motor neuron size
Synaptic strength determines:
Recruitment order
Short-term synaptic plasticity
Synapses change strength a little bit as they are used, but the connection remains relatively stable
Longer-term synaptic plasticity
Basis of learning and memory
Aplysia model of learning
1) Gill withdraws the siphon when siphon touched. Responds less with time.
2) Response heightened by noxious stimuli to the tail/ Serotonergic activation of PKa, makes K+ channels deavtice in the sensory-motor synapse.
3) Serotonin - important molecule modulating motor activity even in humans
Long-term potentiation
Induced by high frequency stimuli to pre-synaptic cell, or paired stimulate to pre and post-synaptic cells whiner pre comes before post.
Addition of AMPA receptors to post-synaptic membrane.
Long-term depression
induced by low frequency stimuli to pre-synaptic cell, or post before pre pairing.
Removal of AMPTA receptors from post-synaptic cell.
