Mechanims of Long term memory :)

Define neuroplasticity

New evidence proving our brain is always adapting to the environment

Brain changing a structure or function as a result of an exp.

• landscaping

What are some benefits for plasticity

• compensate for loss of function

• To adjust activity in response to new situations or changes in the environment (play sports/instruments)

What are the principles of neuroplasticity?

• increase in use of an area → lead to its expansion

• Synchronous firing leads to integration of cortical zones

• Asynchronous firing leads to segregation of cortical zones

• Disuse or damage to a brain area results in neurons from surrounding areas encroaching on the unused cortical area

List the mechanisms of plasticity

• increase/decrease in NT

• Increase in dendritic length

• Increase/decrease in spine density

• Formation of new synapses

• Increase in glial activity

• Alterations in metabolic activity

What does the saying “neurons that fire together, wire together” mean?

• If cell A contributes to firing of AP In B there will be diff mechanims that strengthen the communication

• Axon of cell A excites cell B and repeatedly takes part in it, some growth processes will change in both cells

What is titanic stimulation and what happens after titanic stimulation

• titanic stimulation is high frequency, repetitive stimulation leading to the motor neuron becoming depolarized & going back to rest

• Post tentative potentiation: a single stim of sens neuron after titanic stimulation leads to an increase in EPSP in the motor neuron, but this effect is short lived

What is long term potentiation

Caused by titanic stim of performant pathways in the hippocampus = increase in post synaptic response to a pre synaptic stimulation lasting hours or longer

How does LTP occur in the hippocampus

Review diagram

What is LTD

• LTD is long term depression and is caused by prolonged low intensity stim that causes some (maybe even just one) NMDA receptor to expel Mg 2+ block

• Therefore leading to a decrease in Ca2+ levels leading to activation of different signaling cascades causing the removal (internalization) of AMPA receptors

• **LTD weakens synapses due to deuction of AMPA receptors, spine shrinkage, spine loss, and reduced dendritic complexity

How do LTD and LTP differ

LTP produces a persistent increase in the strength of synaptic transmission, while LTD produces a persistent decrease

How would an increase or decrease in neurotransmitter affect plasticity?

• an increase can increase synaptic strength through LTP

• A decrease can weaken synaptic strength in LTD

How would an increase in dendritic length affect plasticity?

By providing a larger SA for synapse formation, increasing the capacity for receiving synaptic inputs, allowing for a greater complexity in how neurons integrate signals.

How would the formation of new synapses affect plasticity

Enhances a brain’s plasticity by creating new pathways for information to travel

How would an increase in glial activity affect plasticity?

• It will lead to a decrease or disruption of normal synaptic plasticity

• It would reduce LTP and LTD

• Disrupt homeostasis

• Lead to impaired NTs

How would alterations in metabolic activity affect plasticity?

Decreased metabolic activity (reduced ATP production) would lead to a decrease in plasticity