L18 Memory Flashcards
What are the two types of memory?
- Procedural
- Declarative
What is declarative (explicit) memory?
Memory that can be consciously recalled (e.g. recalling riding a shiny new bike on the Christmas day when you were 5)
What is procedural (implicit) memory?
Memory that involves remembering how to perform certain actions and skills.
It’s essentially the memory of “how to do” things, rather than “what” things are. Examples including: riding a bike, typing on a keyboard
What are the three different types of memory duration?
- Immediate memory - Few seconds
- Short - term memory - Seconds or minutes.
- Long - term memory - days, months, years.
What does electrical stimulation of the temporal lobe cause?
It induces hallucinations and recollection of the past experiences
What is expected to happen if someone undergone temporal lobectomy?
Lobectomy - removal
Extreme anterograde amnesia (inability to form new memories)
Name the important structures of the brain for memory.
- Pre-frontal complex - working
- The hippocampus - essential for converting short to long term memory.
- Amygdala - Fear response, multiple sensory inputs.
- Cerebellum - Procedural, sensorimotor (sports related)
What does hippocampus lesions cause?
Hippocampal lesions (elective or accidental) cause memory loss
What is the structure of hippocampus (4)?
- Three layered cortex
- Receives inputs from entorhinal cortex and beyond
- Outputs to many regions
- Enlarged in people whose work requires good spatial memory.
What are the mechanisms of memory?
- Long-term storage seems to be distributed
- Reverberating circuits
- The Hebbian synapse concept
What is the Hebbian synapse concept?
A theory suggesting if neurons fire together, the connection between those neurons becomes stronger
Describe the synaptic plasticity in relation with the Hebbian synapse concept
- Synaptic strength changes can be: Facilitation/depression
- Facilitation is when connection becomes stronger due to increased availability of Ca2+/ vesicle depletion
- Depression - reduced release of vesicles therefore weakening the strength.
Can be short term (mins/hours) or sustained (days/weeks+)
What is long term potentiation?
LTP is how your brain reinforces the connections between neurons that are used frequently, making it easier for those neurons to communicate in the future.
This reinforcement is what allows you to learn and remember.
LTP in hippocampal slices
What are the characteristics of LTP?
- Coorperativity: Simultaneous activation of a sufficient number of presynayptic inputs to trigger LTP
- Specificity: Only occurs at synapses that were active during induction process
High frequency
What happens to EPSP if a synapse undergoes long term depression (LTD)?
If a synapse undergoes LTD then neurons are fired at a lower frequency therefore decreases amplitude
What is sensitisation?
Refers to an increased responsiveness to a stimulus after repeated exposure to it
What are the features of LTP,LTD and Aplysia?
- Require receptor activation
- Altered synaptic responsivity
- Mediated by second messengers (Ca2+/cAMP)
- Require protein phosphorylation in early stages
- Require protein synthesis for late stages.
How does LTP occur?
1) Glutamate released into synaptic cleft
2) Glutamate binds to AMPA and NMDA receptor
3) NMDA receptor allows calcium ions to flow through which activates kinases which phosphorylates the AMPA receptor
4) AMPA causes depolairsation of the membrane on the postsynaptic membrane
