Biological Basis of Memory Flashcards
What do conditions makes people tend to do poorly in implicit memory?
Give an example of a condition?
Conditions affecting their striatum.
Parkinson’s or Huntington’s disease.
What part of the brain is important for declarative memory?
The medial temporal lobe and the hippocampus.
What happens in the medial temporal lobe?
The memories change from being STM to LTM, this is called consolidation.
What 4 factors is consolidation affected by?
- The depth of stimulus processing.
- Distinctiveness
- Relevance
- Emotionality
What do stressful or emotionally exciting experiences increase?
The secretion of adrenaline (aka epinephrine) and cortisol.
What area of the brain does cortisol activate?
The amygdala and hippocampus where they increase memory consolidation and storage.
What part of the brain does the amygdala stimulate?
What does this do?
The hippocampus and cerebral cortex which increases memory storage.
Why does greater processing of negative or threat related information have an evolutionary advantage?
Allows for better avoidance of dangerous situations.
How can prolonged stress affect memory?
Impairs memory as it increases large amounts of cortisol.
What state is a memory in when it is reactivated?
What is the memory like in this state?
A labile state.
It is fragile or malleable, it can be weakened or altered or strengthened.
What brain regions do consolidation and reconsolidation use?
Evidence suggests they rely on the same brain regions and same proteins.
How are memories created in the brain?
Due to changes happening at synapses between neurons.
When do changes in synapses that create memories occur?
When one or more axons bombard a dendrite with stimulation.
What synapses does long term potentiation depend on?
Glutamate synapses. The most prevalent excitatory neurotransmitter in the brain.
What 2 types of glutamate are important in long term potentiation?
AMPA and NMDA.
These are 2 ionotropic receptors.
Why are AMPA and NMDA call ionotropic receptors?
Because when they are stimulated, they open channels for ions to pass through.
What channels does AMPA open?
Sodium channels when stimulated by glutamate
What does NMDA’s response to glutamate depend on?
The polarity of the membrane - sodium can come in until it is depolarised.
What charge do magnesium ions have?
What are they attracted to?
. Positive
. Negatively charged cells but that are too big to get through NMDA receptors channels, so just sit there blocking it.
What action depolarises the membrane?
Why is this?
Repeated glutamate of AMPA receptors.
because the AMPA receptor is letting positively charged Na+ into the cell - making the membrane potential more positive.
What does the depolarisation displace?
Magnesium molecules that had been blocking NMDA receptors.
Why were the Mg molecules attracted to the cell?
What happens if the cell becomes less negative?
Because the cell was negative, and the Mg molecules are positive.
They are not so strongly attracted and dislodge. This leaves the NMDA channel free for other ions - at which point sodium (Na+) and Calcium (Ca++) come flooding.
What protein does calcium activate?
What does this protein begin?
CaMKII.
Begins a series of reactions that leads to the release of a protein called CREB.
What protein magnifies the effects of CaMKII and CREB?
BDNF
What is the factor that determines which neurons will undergo long term potentiation?
Only those with the highest concentration of CaMKII, CREB and BDNF will undergo long term potentiation.
What can changes in the presynaptic neuron cause?
Long term potentiation.
Extensive stimulation of a postsynaptic cell causes the release of a retrograde. transmitter that travels back to the presynaptic cell to cause what 4 changes?
- Decrease in action potential threshold.
- Increase neurotransmitter release.
- Expansion of the axons.
- Transmitter release from additional sites.
What are the 3 properties in long term potentiation?
- Specificity
- Cooperativity
- Associativity
What improves declarative and procedural memory?
Sleep
What kind of sleep enhances retention of declarative (mainly episodic) information and non-declarative procedural performance?
Compared with a period of wakefulness of equal length, a period of post learning sleep enhances it.
What memories does sleep protect?
When is sleep beneficial for learning?
Newly learned declarative memories from interference.
The beneficial effects of sleep are enhanced if sleep takes place immediately after learning rather than after a delay.
What type of learning is sleep deprivation associated with?
What can sleep deprivation cause re memory?
Explicit learning.
Memory problems.
What is the simplest explanation for forgetting long term memories?
Decay, it is a passive process.
Forgetting: Give a brief overview of interference
- Memories acquired on different occasions interfere with each other.
- The similarity between the memories affects interference.
- Retroactive interference - acting backwards.
- Proactive interference - acting forwards.
What are event-related potentials a measure of?
Electroencephalogrpahy (EEG).
Give an example of clinical forgetting.
Amnesia
