Neurophysiology of Learning and Memory Flashcards
What is procedural memory?
Motor skills that are learned and are automatic
Also implicit memory
What structures are required for procedural memory?
Cerebellum for the motor part
Nucleus accumbens for non motor
What is declarative memory?
Learned facts (episodic are events and semantic are memory of rules related to language) Explicit memory
What structure is required for declarative memory?
cortex
Short, long and working memories. How are these processed?
- seconds to hours
- years
- recalling a memory for use
Processing each type have different physiology!
What is required to actually make memory?
Physically changing the neuron itself or the synapses it makes (neuronal or synaptic plasticity)
What is post-tetanic stimulation?
Synaptic plasticity mechanism
High frequency release of NT from pre-synaptic neuron > more bouts of Ca2+ entering the cell > greater NT release which increases the chance of AP in post synaptic cells
What is long term potentation?
EAA stimulates pre and post synaptic neurons to change > results in increase response to the NT released at the synapse
Using the EAA model, describe LTP
EAA binds non-nmda and nmda (with Mg+) receptors > Non-NMDA able to let Na+ in > depolarization > kicks Mg+ out of the NMDA receptor so calcium can enter its channel
What overall effect does calcium have after entering the cell?
Increase post synaptic response and NT release
Describe how Ca2+ alters post synaptic response via calmodulin
CA2+ binds calmodulin > increase cAMP > phosphorylation of AMPA receptors > increased Na+ influx > more depolarization > increased post synaptic response
Describe how CA2+ alters post synaptic response via calcineurin:
Ca2+ binds calcineurin > activate NOS > create NO > diffuses across cells and increases cGMP and NT release
What is CREB?
cAMP response element binding protein. Activated and induces gene transcription changes in pre and post-synaptic cell (neuronal plasticity) that produce proteins for new synapse (makes more NT, receptors, post synaptic density etc)
What happens to learning and memory if protein synthesis is blocked?
Block learning and formation of new memories
What are the 4 steps required to make explicit memories?
Encoding
Storage
Consolidation
Retrieval
What is encoding and what can enhance it?
Focusing on the new info.
We can link it to previous memories or relate it with emotion
The main player in information storage are
Short term memory (hippocampus, parahippocampal cortex, prefrontal cortex)
How does the short term memory system work?
Projections from the main structures > Meynart > release Ach > neocortex and amygdala. (cholinergic) > excites the system to threshold leading to new memory formation
Explain the relationship of Alzheimer’s disease to short term memory
Alzheimer’s targets the cholinergic system to Neocortex and amygdala. Results in difficulty making short term memories
How do you physiologically store a memory in Short term memory?
Strengthening the synapses between the neurons in the hippo, parahippo and prefrontal (long term potentiation) allows info storage in short term memory (fire together)
What is consolidation?
Making a memory permanent
Involves physically changing the synaptic structure of neurons that have LTPd with each other
What anatomical structures are required to consolidate memory from short to long term?
Hippocampus
Temporal lobe
Papez circuit
What is the Papez circuit pathway?
Hypothalamus/mammillary bodies > anterior thalamus > cingulate cortex > hippocampus (activation of relevant memories happens over and over)
How does the Papez circuit work?
Continuous activation of the neurons in these areas related to the memory (neurons that fire together synapse together)
Papez in limbic system is required to encode, but not to retrieve
