Pharmacological Modulation of Memory Flashcards
(40 cards)
What is memory?
the term given tot he process and structures involved in storage and subsequent retrieval of information
3 stages of memory
- Encoding: - sensory input is relayed into the brain (thalamus - processing centre) and is subsequently relayed into e.g., occipital lobe towards the visual cortex or amygdala for fear responses → determine how we will interpret that experience (i.e., if that information is attended to or not) SUBJECTIVE
- Storage: - associated with neural networks, in short term can be quite plastic → through rehearsal these memories are maintained - consolidates memory, which can lead to long term encoding which can be easily retrieved
- Retrieval
Explicit (Declarative) Memory
Facts, Events, People, Places and object
→ mainly mediated in the hippocampus
→ conscious attention is necessary for recall
Implicit (Procedural) Memory:
Unconsciously recalled
→ Skill & Habits: Striatum, affected in PD - affecting motor functions
→ Associative learning: Amygdala (Emotional response) & Cerebellum (Movement skills)
→ Non-associative learning: Habituation and sensitisation - reflex pathways which we can’t consciously control but can affect attention
What is meant by “Semantics”?
to make meaning of something - is it a good or bad memory - i.e., is it a good or bad experience, depending on the impact it made determines whether or not it gets processed into a longer term memory
Factors which can affect memory in a negative way
- Old age
- Stress
- ADHD
- Schizophrenia (Negative Symptoms)
- Anxiety/Depression
- Sleep Deprivation
How does electroshock therapy affect memory?
Has a serious negative impact on retrograde memory
ADHD is believed to be due to…
a lack of connection between neurons in the prefrontal cortex
Relay centre for memory storage
Hippocampus
How was learning and memory linked to the hippocampus?
Patient H.M.
→ intractable temporal lobe epilepsy. Bilateral removal of H.M.’s temporal lobe & hippocampus cured his epileptic seizures. Declarative memory was impaired. Procedural memory was intact.
Age-associated hippocampal atrophy corresponds to..
cognitive decline
Hebb’s Rule
Cells that fire together wire together (synaptic efficacy arises from presynaptic cell repeatedly stimulating postsynaptic cell)
A key aspect of memory depends on
Glutamate
NMDA glutamate receptor
-heteromeric ion channel
- 4 subunits (2x NR1, 2x NR2)
- glutmate binds NR2
- glycine (co-agonist) binds NR1
NMDA receptor antagonists
Memantine, Amantadine, Ketamine, PCP (angel dust)
Overactivation of glutamate receptors can induce
Excitotoxicity
What minerals can inhibit the NMDA receptor
Zinc and magnesium
Resting membrane potential of a neuron
-40mV
Competitive inhibitor of the active site of the NMDA receptor
APV
Selective competitive AMPA receptor antagonist
CNQX
What is the net result of administering APV and CNQX together?
No Glutamte Response
Long term potentiation
A lasting, activity-dependent increase in synaptic efficacy (repeated firing of neurons strengthens synaptic connections)
Molecular changes in LTP
- Glutamate activation of NMDA receptors allow Ca influx which activated Ca/calmodulin-dependent protein kinase, causing phosphorylation of non-NMDA receptor channels to increase sensitivity to glutamate
- Repeated AP trains activate NMDA receptors, activating AC and a sensitisation cascade
- Late LTP is thought to give rise to growth of new synaptic connections
What is a potential target for novel memory enhancers, and why?
CREB transcription factor - transcribes genes involved in forming new synaptic connections
