Memory and Amnesia Flashcards
What are the two main types of long term memory
- declarative
- non declarative
What are the two types of declarative memory
- episodic - personal episode’s in time and space
- semantic - facts, meanings, concept and knowledge
- these require conscious recall
What is a type of non-declarative memory
procedural - skills and habits
- this does not require conscious recall as you automatically know how do to it
What areas of the brain is associated with episodic and semantic memory
Episodic
- hippocampus,
- medial temporal lobe
- neocortex
Semantic
- lateral and anterior temporal cortex
- prefrontal cortex
What area of the brain is associated with procedural memory
- Striatum
- cerebellum
- motor cortex
What is the major cellular mechanism for learning and memory
- Long term potentiation
Describe the theory behind how Long term potentiation works
LTP is the persistent strengthening of synapses, which causes a long-lasting increase in signal transmission between 2 neurones.
The repeated stimulation of a synapse causes more dendritic receptors to appear,
which increases the amount of NT and leads a stronger link.
What happens in long term depression
- This is the opposite to long term potentiation
- this is when the memory is no longer needed and not recalled therefore the synapses involved in the memory will reduce in weakness
What receptors is LTP and LTD heavily involved with
• LTP/LTD is heavily involved in NMDA and AMPA receptors that bind glutamate.
What is
- anterograde amnesia
- retorgrade amnesia
- dissociative amnesia
Anterograde Amnesia:
New events are not transformed to long-term memory.
Retrograde Amnesia:
Unable to recall events which have happened before the onset of amnesia.
Dissociative Amnesia:
Blocking out of critical, personal information.
What are the processes required for information to be learned
- Input: acquisition (perception and encoding)
- Hold: storage (consolidation and maintenance)
- Output: retrieval (performance, recall, recognition).
Why might you forget information
Forgetting: may be due to temporal decay/interference from other learning.
• Most input is immediately forgotten
What memory is distorted in scizhiophrenia
Semantic memory, this usually depends on the prefrontal cortex which can be distorted in schizophrenia
What area of the brain is important for priming and perceptual learning
neocortex
What are of the brain is used in simple classical conditioning
Amygdala and cerebellum
Name 3 types of amnesia
- anterograde
- retrograde
- dissociative
What is involved in spatial memory
the hippocampus
- this allows you to be aware of your surroundings
What happens to receptors in LTD
If weakened pre-synaptic signal = only AMPA activated.
NMDA channel remains closed because it spore is blocked by Mg+ ions.
what happens to receptors in LTP
Large amount of glutamate release and binds to AMPA post-synaptically.
• AMPA stay open longer = greater depolarization.
This expels magnesium from the NMDA channel.
• This also allows calcium into the cell which allows LTP induction.
o Gene transcription to create new proteins for memory formation.
What are the causes of amnesia
- physical trauma
- infection
- drug and alcohol abuse
- reduced blood flow to the brain
- infections such as encephalitis and herpes
What does the ability to make LTP depend on
- Synapse number
- Release probability – increase the release probability by increasing the action potentials generating EPSP
- AMPARs their number, phosphorylation state or indeed a combination of the above
How can LTP and LTD both be dependent on NMDARs and Calcium
- LTP and LTD are complementary types of plasticity
- The size and time course of NMDA receptor activation and calcium influx differ between LTP and LTD induction
- Induction of LTP produces a large intracellular calcium rise for a short period of time
- Induction of LTD produces a smaller rise in calcium over a longer time scale
- This leads to differential activation of enzymes with different sensitivities to calcium
- Kinases involved in LTP are relatively insensitive to calcium and therefore need a big calcium change to be activated
- Phospatases involved in LTD are relatively more sensitive to calcium and therefore are activated by small calcium changes
