Memory Flashcards
What is the definition of learning?
Acquisition of information
What is the definition of memory?
Storage of learned information
What is the definition of recall?
Reaquisition of stored information
What is the definition of engram?
- Physical embodiment of memory
hypothetical permanent change in the brain accounting for the existence of memory; a memory trace
What is procedural memory?
Learnt skills and associations largely UNAVAILABLE to the conscious mind
- Eg. habits, mannorisms, playing the piano
What is declarative memory?
- AVAILABLE to the conscious mind
- Can be encoded in symbols and language
- Can be transmitted to somebody else
- Eg. events that have happened, information
How is memory classified?
On how long a memory lasts:
- Immediate: a few seconds
- Short term: seconds or minutes. Involves ‘working memory which is problem solving.
- Long term : days, months, years
Where is working memory held?
In the pre-frontal cortex
What is the involvement of the hippocampus in memory?
- Converts short-term memory into long-term memory
- Majority is declarative
What is the involvement of the amygdala in memory?
- Processes multiple SENSORY inputs (eg. smell) either directly or indirectly
- Activated by implicit/ emotional/ learnt fear
What is the involvement of the cerebellum in memory?
- Procedural memory
- Sensorimotor skills (both motor and sensory
What does hippocampal lesions cause?
- Cause memory loss and inability to lay down new memories
- But can still recall old memories
What are they layers in the hippocamupus and how is this different to the rest of the cortex?
3 layers:
- Polymorphic
- Pyramidal
- Molecular
Rest of the cortex has 6 layers
What are the 4 sections of the hippocampus?
1) Dentate gyrus
2) Cornu ammonois
- CA1 to CA4
3) Subiculum
4) Parahippocampal gyrus
Where do the inputs into the hipocampus come from?
The entorhinal complex and beyond
What are outputs from the hippocampus via?
The fornix
How is long term memory stored?
It is distributed - stored in many areas of the brain
What is the Hebbian synapse concept?
- Memory is stored at a cellular level at synapses
- Synapses become stronger/weaker based upon previous experience
- Activity modifiable
What circuits are used in memory?
Reverberating circuits
- Stimulation with the right input will lead to memory reappear
What is synapse plasticity?
Synapse strength can change in response to increases or decreases in its stimulation:
Facilitated = stronger
Depressed = weaker
- Can be either long-term or short-term
What is LTP? Describe the process
- Long term potentiation (increase strength of nerve impulses)
- Cells in CA3 send schaffer collaterals (processes) to cells in the CA1 region
- CA1 can inputs from many cells in the CA3 region
- The CA3 inputs can be experimentally stimulated by post-tetanic LTP or paired LTP
What causes the short-term change in synapse strength?
- Ca2 avalibility
- Vesicle depletion
What is post-tetanic LTP?
- High frequency stimulation of the pre-synaptic neurons (pre-tetanic)
- Input specific
- Stimulate pathway 1 results in an increase in the EPSP generated in the post-tetanic
- Stimulate pathway 2 results in no change in EPSP generated in post-tetanic
What is paired LTP?
- Stimulation of the target cell directly (CA1 as well as the schafffer collaterals
- Leads to a strengthening of the CA1 response
- Coincident stimulus and direct depolarisation
- Strengthening can occur if the two inputs are received at the same time
What does the gill withdrawal reflex show?
- Habituation (reduced respomse with multiple exposurs over time)
- Short and long term sensitisation
