Learning and Memory Flashcards
Learning
Acquisition of new information or knowledge
Memory
Storage or retention of acquired knowledge
Engram - definition
Physical representation or location of memory
Cortexes involved with memory
Temporal, parietal, olfactory and prefrontal
Brain areas concerned with declarative memory
Hippocampus
Parahippocampal cortex
Brain areas concerned with emotional memory
Amygdala
Hypothalamus
Brain areas concerned with procedural memory
Cerebellum stores movement-based memory
Brainstem
Striatum
Declarative memories
Things you think about
Episodic
Somatic
Emotional memory
Preferences and aversions
Procedural memory
Motor skills
Associations
Priming cues
Puzzle solving
HM
Had his temporal lobes removed to treat epilepsy
Could not form new explicit memories, but long term procedural was intact
Severe anterograde amnesia
Hebb’s law
When two neurones are active together then that synapse will become stronger.
Synapses strengthened by intense activity
Memory depends on populations of interacting neurons
Pattern of strengthened synapses defines memory
Engram
The pattern of closely connected neurons that forms a physical memory
How do we study synaptic strengthening?
The recording of the membrane potential of neurons
How does a synapse get stronger?
If there are a lot of action potentials in a short time, there is a potentiated AMPAr EPSP
This causes the strengthening of the synapse and can last forever
What is EPSP
Excitatory Post-Synaptic Potential
What is the increase in strength after repeated stimulation called?
Long Term Population (LTP)
Dual gating of NMDA receptor
Have a magnesium block, so can only fire when the cell is depolarised.
Glutamate must bind as well.
Both Ca and Na can then flow through the NMDAr channel
NMDA and memory
Depolarisation to repetitive activation of AMPAr relieves Mg2+ block
Both Ca and Na flow through NMDAr channel
Ca-entry causes cellular changes that lead to increased AMPAr response – LTP
How is LTP manifested Postsynaptically?
More AMPAr
More sensitive AMPAr
More synapses
How is LTP manifested presynaptically?
Increased release
More release sites
More vesicles
LTP induction mechanisms
- Burst of activity releases glutamate and activates NMDA
- Phosphorylation of AMPAr by PKC
- Insertion of new receptors by CaMKII.
- Synthesis of new receptors
- Retrograde messenger – such as nitric oxide - presynaptic changes
- Synthesis of new AMPA receptors and exchange of AMPA receptor subunits
Phosphorylation of AMPAr by PKC
PKC here but also other kinases are involved
This phosphorylation is what leads to hypersensitive AMPA receptors
NMDAr antagonists will _ learning
Inhibit
Composition of a memory
It is in fact made up of several different types of memory
These can include association and priming cues.
Classical conditioning and memory
Triggers
This links to addiction and craving due to association
Reactivating a memory _ it
Strengthens
Examples of cognition enhancers
- Cholinergic modulation: anticholinesterases - donepezil (Aricept), galantamine or agonists - nicotine, arecoline
- Stimulants - amphetamine, methylphenidate, modafanil, caffeine
- 5HT drugs – particularly 5HT6 antagonists
- GABAA receptor blockers - inverse agonists – suritozole
- AMPAkines - positive AMPAr modulators - piracetam, IDRA-21
- mGluR drugs – particularly mGluR5 positive allosteric modulators
Causes of amnesia
Drug induced such as alcohol
Head trauma - temporary or permanent
Retrograde amnesia
Retrograde is a struggle to recall preexisting memories
Anterograde amnesia
Anterograde is the inability to form new memories
Dementias
- Loss of multiple memory categories
- Inability to form new memories (learning)
- Associated with general cognitive decline
- Memory impairment first presenting symptom
