Synaptic Plasticity
SYNAPTIC PLASTCITY:
Neuroplasticity: the brain’s ability to change as a result of it’s experiences, causing the brain to physically change, the brain’s flexibility and learning capacity
refers to the ability of synaptic connections to change in response to experience
involves creating, strengthening or weakening connections that impact the flow of information
if we are making the same mistake over and over again we want to correct it, so eliminate the mistake pathway and establish a new pathway
when synaptic connections are strengthened= more likely to fire together and relay messages more effectively
when synaptic connections are weakened they are less likely to fire together and relay messages more effectively
There are 2 types of neural plasticity:
Adaptive: when neurons have to adapt and respond to something e.g brain damage, neurons have to take on new roles. The younger you are the easier it is to adapt to these changes. By utilising critical periods for developmental plasticity it helps to enable greater adaptive plasticity
Developmental: it occurs naturally across the lifespan, there are certain periods called “Critical periods” where individuals obtain large amounts of neurons. These “critical periods” enable greater developmental plasticity.
as we develop, our ability to think and reason also develops
Synaptic Plasticity- the process of neuroplasticity at a single cell level
when synaptic connections change over time in response to activity or experience
Hebb’s rule: neurons that fire together, wire together
Plasticity enables fast response times
Can also be defined as changes in the presynaptic neuron, neurotransmitters and the post synaptic neuron
changing of these neural pathways is called Long Term Potentiation (LTP)
LTP= increase in synapse strength due to high frequency stimulation (regular use) of the neural pathway
LTP makes it hard to change habits
If the presynaptic neuron is being regularly used, more axon terminals may form to send more messages more quickly
If the post synaptic neuron is receiving a lot of messages more dendrites may be produced for efficiency
Axon terminals can learn to target certain cells and dendrites grow more branches and become “bushier” so they can receive more information
When neurotransmitters are sent often enough from one neuron to another, they “consolidate” together forming a neural pathway
Synaptogenesis vs. Synaptic Plasticty
Synaptogenesis is the creation of a brand new pathway that didn’t exist before
Synaptic plasticity is the strengthening and weakening
Long Term Depression: the reduction of the efficiency of synaptic connections
LTD is long lasting and experience-dependent weakening of synaptic connections between neurons that are not regularly fired
these connections will reduce and become more simple, allowing this potential to be used for new skills and neurons
The younger you are the easier it is to redirect neurons, however you never lose the potential to have synaptic or neuroplasticity
Neural Processes
Proliferation: when you are born and create a lot of neurons
Migration: neurons move to the areas they are needed most
Circuit Formation: neurons find other complimentary neurons and create synapses, forming a circuit
Circuit Pruning: if not using circuit, body may get rid of circuit
Myelination: if circuit is used regularly, connections strengthen
Synaptic Plasticity is possible as a result of 3 neural processes: sprouting, rerouting and pruning
Sprouting: creation of new connections between neurons
Rerouting: re-establishing neural connections by creating alternate pathways- moving them
Pruning: removing old neural connections that are no longer adequately activated
Sprouting:
creation of new extensions on neurons to increase the likelihood and number of new connections with other neurons
extra nerve endings grown on both axon terminals and dendrites to make them “bushier”
filigree appendages are the extra growth off the axon terminals of the presynaptic neuron increasing the number of release sites for neurotransmitters
this increases surface area of the neuron, and increased surface area increases the efficiency of neural transmission
Rerouting:
alternative pathways for different connections are created between neurons
these “new” routes often occur due to damage to neurons or areas of the brain, or to correct mistakes
Pruning:
eliminates weak, ineffective or unused connections
this can make our brain stronger and more efficient
experience determines which synapses will be retained and strengthened and which will be pruned away
the more experience, practice, repetition and rehearsal, the more established and robust the pathway
we are not completely getting rid of them, we are just cutting them back
Synaptogenesis
most prolific in the first years of life
experience and environment play a significant role in neural network development
research suggests that children or animals raised in non-stimulating environments suffer limited synaptogenesis, form weaker neural networks and have impeded learning and memory potential
children or animals raised in enriched/stimulating environments develop greater synaptic functioning, stronger neural circuits, have better learning and memory outcomes and more positive bran growth
Long Term Potentiation:
refers to the strengthening of synaptic connections from repeated coactivation, enhancing the communication between neurons/increasing information transfer between neurons
increased tendency of the presynaptic neuron to activate the action potential of the postsynaptic neuron by releasing neurotransmitters across the synapse, over time
the postsynaptic neuron becomes more responsive to the presynaptic neuron as a result of repeated stimulation
with repetition of this process learning occurs and memory traces are formed
Long Term Depression:
refers to the weakening of synaptic connections from reduced coactivation, decreasing the transmission of information between neurons
the postsynaptic neuron becomes less responsive to the stimulation of the presynaptic neuron weakening the connection and reducing the communication of information
this explains how unwanted or incorrect behaviours are blocked and eliminated so that we don’t keep making the same mistakes over and over again
Example: Learning how to serve in tennis
LTP: strengthens neural connections for the right movements
how high to throw the ball, when to swing, what angle to hold your racquet
LTD: weakens neural connections, pruning away incorect actions and eliminating mistakes
throwing the ball at the wrong angle, swinging the racquet to early
How did this person learn from their mistake?
The brain performed long term depression to prune back the neural pathways that correlate with the incorrect action. Long term potentiation then occurs to strengthen the neural pathway that correlates with the correct action