2D - Synaptic Plasticity

Question 1

define synaptic plasticity

Answer 1

the ability of synaptic connections to change over time in response to activity or experience

Question 2

three mechanisms of synaptic plasticity:

Answer 2

• sprouting
• rerouting
• pruning

Question 3

define sprouting

Answer 3

the ability of dendrites or axons to develop new extensions or branches

Question 4

define dendritic spines

Answer 4

a dendrite fibre that grows by sprouting on the post-synaptic neuron

Question 5

define filigree appendages

Answer 5

a fibre that grows by sprouting from the axon terminal of the presynaptic neuron

Question 6

define synaptogenesis

Answer 6

the formation of new synapses that result from the process of sprouting

Question 7

define rerouting

Answer 7

the formation of new connections between neurons to establish alternative neural pathways

Question 8

define pruning

Answer 8

the removal of excess neurons and synaptic connections to increase the efficiency of neuronal transmissions

Question 9

define learning

Answer 9

the process of acquiring knowledge, skills, or behaviours through experience

Question 10

define memory

Answer 10

the process of encoding, storing, and retrieving information that has been previously encountered

Question 11

Synaptic plasticity in learning and memory

Answer 11

• Synaptic plasticity is the fundamental mechanism of memory formation that leads to learning.
• When you form new memories, neural synapses in your brain physically change in response to these experiences.
• These changes to synaptic connections establish neural pathways that incorporate these memories and represent what has been learnt.
• These neural pathways that form during learning are referred to as memory traces, with each memory trace representing a different memory

Question 12

define co-activated

Answer 12

activated together
- the neural pathway associated with one thing and the neural pathway associated with another thing are activated at the same time, strengthening these synaptic connections

Question 13

There are two forms of synaptic plasticity that underlie learning and memory

Answer 13

• long-term potentiation
• long-term depression
• both involve the long-lasting strengthening or weakening of synaptic connections in neural pathways in response to increased or decreased coactivation

Question 14

define long-term potentiation

Answer 14

the relatively permanent strengthening of synaptic connections as a result of repeated activation of a neural pathway

Question 15

why does LTP occur?

Answer 15

• An increase in receptor sites on the postsynaptic neuron
• Dendrites become bushier (sprouting), resulting in more synaptic connections

Question 16

process of LTP in learning and memory

Answer 16

• During learning and memory, neurotransmitters are repeatedly released into the synaptic gap by the axon terminals of the presynaptic neuron and received by receptor sites on the dendrites of the postsynaptic neuron.
• This repeated coactivation of the presynaptic neuron and postsynaptic neuron, or this repeated high-intensity stimulation of the postsynaptic neuron, strengthens the synaptic connection between these neurons
• Glutamate is released each time a neural pathway associated with an experience is activated

Question 17

structural changes of LTP

Answer 17

• increased number of receptor sites on the dendrites of the postsynaptic neuron
• bushier dendrites on the postsynaptic neuron due to sprouting
• increased number of synaptic connections between neurons due to sprouting

Question 18

changes that occur to a neural synapse due to long-term potentiation

Answer 18

• The increased strength of synaptic connections in a neural pathway makes postsynaptic neurons more receptive to neural signals from presynaptic neurons and consequently more readily activated.
• This increases the efficiency of synaptic transmission along the neural pathway.
• In this way, when this specific neural pathway is activated once again, neural signals are transmitted more rapidly and efficiently

Question 19

define long-term depression

Answer 19

the relatively permanent weakening of synaptic connections as a result of repeated low-level activation

Question 20

why does LTD occur?

Answer 20

• The number of receptor sites on the postsynaptic neuron decreases
• Pruning of dendrites on the postsynaptic neuron results in fewer synaptic connection

Question 21

process of LTD in learning and memory

Answer 21

• It helps our brain to adapt or change neural pathways and to get rid of or ‘prune’ neural connections that are no longer useful.
  If a neural pathway that has been previously established during learning and memory is no longer regularly activated, long-term depression weakens the synaptic connections in this neural pathway that is no longer necessary.
• The weakening of a neural synapse involves the infrequent release of neurotransmitters into the synaptic gap by the axon terminals of the presynaptic neuron.
• This low-intensity stimulation of the postsynaptic neuron weakens the synaptic connection between the presynaptic neuron and the postsynaptic neuron.
• The decreased strength of synaptic connections involves structural changes occurring to the neural synapse.
• These structural changes are a result of the decreased release of neurotransmitters into the neural synapse due to long-term depression

Question 22

structural changes of LTD

Answer 22

• decreased number of receptor sites on the dendrites of the postsynaptic neuron
• decreased number of dendrites on the postsynaptic neuron due to pruning
• decreased number of synaptic connections between neurons due to pruning

Question 23

changes that occur to a neural synapse due to long-term depression

Answer 23

• The decreased strength of synaptic connections in a neural pathway makes postsynaptic neurons less receptive to neural signals from presynaptic neurons and consequently less readily activated.
• This decreases the efficiency of synaptic transmission along the neural pathway.
• By weakening memory traces that are not regularly activated, long-term depression enables the brain to accommodate more necessary memory traces that represent more relevant information, and are consequently activated more frequently.
• In this way, long-term depression regulates the number of synaptic connections in the brain, ensuring an optimal number is present for learning and memory.
• Furthermore, it is important to understand that these weakened memory traces can be restrengthened through long-term potentiation if they are later reactivated

Question 24

Modifications resulting from LTP and LTD

Answer 24

• When tweaking its construction, the brain works like a sculptor – starting with more than it needs so it can carve away the excess and achieve the perfect design.
• This sculpting occurs via LTP and LTD, acting together to modify synaptic connections between neurons in our brain, making the process of learning more efficient.
• Specific modifications can be identified as a part of this process, including sprouting, rerouting and pruning