Where is memory stored?
Medial temporal lobe
What did patient HM tell us about memory?
Bilateral resection of medial structures of the temporal lobe, to treat severe epilepsy
Profound impairment of recent memory in absence of other intellectual loss
Could not remember what he had for breakfast, find his way around the hospital or recognize anyone he had met since the surgery
MRI Reveals – Medial Temporal Lobe Lesion
What effect does resection of the medial temporal lobe structures have?
Able to hold immediate impressions in mind but as soon as attention is diverted, memories are lost.
Can recall memories from childhood.
What happens to task learning following resection of medial temporal lobe structures?
Patients demonstrate task improvement but are unable to recall having previously done the task (unconscious memory?)
What are the 2 different types of memory?
What are some examples of declarative memory?
Facts and events
What are some examples of nondeclarative (implicit) memory?
Skills and habits
Basic associative learning (emotional responses; skeletal musculature)
Non-associative learning (reflex pathways)
Which structure is involved in declarative (implicit) memory?
Medial temporal lobe
What does hippocampal size correlate with?
Structural MRI showed enlarged posterior hippocampi in London cabbies compared to non-drivers
Which receptor is crucial for learning?
NR1 knockout mutation removes NR1 NMDA receptor component.
What does the hippocampus store?
What is LTP?
The creation of memories.
Production of new proteins is required to change synapses and lay down new memories.
Which protein changes are seen in LTP?
Shift to NR2A subunit after development
NR2B allows more calcium through, allowing for higher potential, more powerful plasticity.
How is short-term memory stored?
Insertion of AMPA receptors
Enhanced presynaptic release via retrograde signalling
How are long term memories stored?
What happened when the NR2B NMDA receptor component was inserted?
Improvements in synaptic strength (memory)
What effect does exercising the brain have?
Release of growth factors (e.g. BDNF) and generation of new neurons
Improvements in mood and memory
Increased blood flow to brain