Chapter 11 Learning and Memory Flashcards
Define Amnesia
Loss of memory, usually as a result of brain injury
What are two types of Amnesia?
- Retrograde Amnesia
2. Anterograde Amnesia
What is Retrograde Amnesia?
“backwards acting”
- cannot remember events prior to brain damage
- loss of past memories
What is Anterograde Amnesia?
“Forwards Acting”
Cannot remember events that occur after brain damage
-inability to create new memories
What surgery did HM undergo?
Bilateral temporal Lobe Resection
complete removal of rhinal cortex, amygdala, and hippocampus
What were the results of HM’s surgery?
Some retrograde amnesia
Severe anterograde amnesia
-his problem was with consolidatin
What was thought to be the initial learning process?
- Sensory Information went into
- Short term memory which was consolidated into
- Long-term memory
What is Short-term memory?
immediate memory, limited capacity
What is Long-term memory?
Memory for past events; unlimited capacity
What is Consolidation?
Process of converting short term memories into long term memories
What were three conclusions based on HM?
- Hippocampus is not the location of long-term memories
- hippocampus is not the location of short-term memories
- hippocampus is involved in converting short-term memories into long-term memories (consolidation)
Brenda Milner disrupted the previous model of learning and replaced it with her “Multiple Memory System”: what was this?
Sensory memory -> short-term memory (working memory) -> Long-term memory
there are two categories of long-term memory, each of which have two subcategories
What are the two categories of long-term memory?
Explicit Memory: Conscious and Voluntary
Implicit Memory: Procedural/Motor = unconscious
What are the two types of explicit memory?
Semantic Memory: explicit for factual info
Episodic Memory: explicit for specific events of ones life
What are the two types of Implicit Memory?
Procedural: learn from doing = difficult to give verbal instructions (eg riding a bike)
Perceptual Memory: unintentional = dejavu
What happened to KC?
Damage to Medial temporal lobes left him with severe amnesia for personal experiences (autobiographical memory)
What is Korsakoffs syndrome?
anterograde amnesia due to alcholism
Those with Korsakoff’s often are nutritionally deficient, what are the effects of this?
Vitamin B deficiency destroys the mammillary bodies and mediodorsal thalamus
What kind of amnesia is common with concussions?
amnesia for events immediately preceding and following the concussion
What is Hebb’s Theory?
Concussions disrupt consolidation
Memories are stored in the short term by neural activity - implies consolidation is rather brief (but is in fact a long process)
What is a controlled method of studying memory consolidation?
Electroconvulsive Shock (ECS) - intense, brief, diffuse seizure inducing current that is administered to the brain and disrupts consolidation
What is the hippocampus’s role in memory storage?
Spatial Location
What is the Perirhinal Cortex’s role in memory storage?
Object recognition
What is the mediodorsal nucleus’s role in memory storage?
Korsakoff’s symptoms
What is the basal forebrain’s role in memory storage?
Alzheimer’s symptoms
What is Hebb’s Rule?
If a synapse becomes active repeatedly at the same time that the post-synaptic neuron fires, the synapse will be strengthened
Define long term potentiation (LTP)
Repeated high strength stimulation strengthen the response of the dentate gyrus so that it will later respond to weaker stimuli
What is Long-Term Depression (LTD)?
Create weaker synapse = never learn
What is Associative LTP?
When a strong stimulus is paired with a weak one their connection becomes strengthened
What two events does LTP require?
- Activation of presynaptic neuron
2. Depolarization of the postsynaptic neuron
NMDA receptors require a two step process because a magnesium ion blocks the Ca2+ channel. What are these steps?
Calcium ion channel is blocked by magnesium - needs to be ejected before Ca2+ can enter
- Depolarization of the membrane evicts the Mg2+ ion and unblocks the channel
- Ca2+ rushes in
What two conditions are required for NMDA receptors to be active?
- Glutamate must be present
2. Postsynaptic membrane must be depolarized
Are NMDA receptors neurotransmitter or voltage dependent?
Both
What is important to note about NMDA receptors with AP5 (amino-5-phosphonovaleric acid)?
- AP5 prevents LTP
however - AP5 doesn’t interfere LTP that has already been established
The strengthening of synapses relates to what?
an increase in postsynaptic AMPA receptors
What are AMPA receptors?
glutamate receptors that control Na+ channels (straight forward, doesn’t require ejection of Mg2+)
What happens after Ca2+ enters the postsynaptic dendrites?
The protein kinase, CaM-KII, is activated and delivers AMPA receptors to the membrane via vesicles
Presynaptic changes may be related to the activation of what?
Nitric Oxide (NO) - can act as a presynaptic messenger
Provide the four steps to how a once-weak synapse changes:
- Glutamate released and binds to NMDA receptor
- Calcium enters and activates CaM-KII which causes insertion of AMPA receptors
- LTP also causes perforated synapses
- Calcium activates NO which diffuses out and back into terminal button to increase glutamate release
