11: Learning, Memory, and Amnesia Flashcards
What is learning?
A process whereby changes in the brain are initiated by experience.
What is memory?
The storage and reactivation of the learning changes.
What is amnesia?
A pathological loss of memory.
What surgery did HM have done on his brain?
- Bilateral medial temporal lobectomy.
- This removed most of the hippocampus.
What is the difference between a lobectomy and a lobotomy?
Lobectomy is the removal of a lobe or most of it.
Lobotomy is the separation, but not removal, of a lobe or most of it from the rest of the brain.
What type of amnesia did HM have post-surgery?
Anterograde amnesia for long-term memories.
What is a well-established test for verbal long-term memory?
The digit span + 1 test.
What is memory consolidation?
The transposition of short-term memories into long-term memories.
What do repetition priming tests measure?
Implicit memory.
What are semantic memories?
Explicit memories for general facts and information.
What are episodic memories?
Explicit memories for particular events in one’s life.
What is cerebral ischemia?
An interruption in the blood supply to the brain.
What type of amnesia does cerebral ischemia cause?
Medial temporal lobe amnesia.
What damage is associated with Korsakoff’s syndrome (3)?
Damage to the medial diencephalon, cerebellum, and hippocampus.
Aside from medial temporal lobe amnesia, what else develops in Korsakoff’s syndrome?
Severe retrograde amnesia.
What causes the reduction of acetylcholine levels in the brains of Alzheimer’s patients?
The degeneration of the basal forebrain.
What is post-traumatic amnesia (PTA)?
Amnesia caused by concussion blows.
What are ‘Islands of memory’?
Surviving memories for isolated events that occurred during periods for which other memories have been wiped out.
What is Hebb’s theory of memory consolidation?
Memories are initially stored in short-term storage, but their structure changes, by means of reverberating, become accessible in the long-term storage.
What is a commonly-used controlled method for studying memory consolidation?
Electroconvulsive shock (ECS)
What is the ‘standard consolidation theory’?
Short-term memories reside temporarily in the hippocampus until they become long-term memories, stored somewhere more stable in the brain.
What does the ‘multiple trace theory’ propose?
The hippocampus and other cortical systems responsible for memory storage will keep memories for as long as they exist.
What is an ‘engram’?
A change in the brain that stores a memory.
What does the ‘delayed nonmatching-to-sample test’ measure?
Object recognition abilities.
What type of brain damage reduced object recognition abilities?
Removal of the medial temporal lobes (like HM).
What is the Mumby box?
The rat version of the delayed nonmatching-to-sample test.
Cerebral ischemia leads to a loss of…
CA1 hippocampal pyramidal cells.
What are the two cortexes that make up the rhinal cortex?
- Entorhinal (within the cortex)
- Perirhinal (surrounding the cortex)
Which rhinal cortex plays a role in object recognition?
The perirhinal cortex.
Rats with hippocampal lesions have serious deficits in what 2 types of memory?
Reference and working memory.
What are place cells?
Neurons that are fired only when an individual is in a specific location.
What is the cognitive map theory?
Hippocampus is a part of the brain that has been specialized for spatial cognition.
Two major findings about memory storage…
- Memories are diffusely stored, so damage in one area of brain doesn’t mean loss of memory.
- Memories are increasingly resistant to destruction over time.
What role does the amygdala have in memory?
Emotional significance of memories.
Prefrontal cortex may have a role in which two types of memory?
Working and temporal memory.
What is the cerebellum’s role in memory storage?
Stores memories for learned sensorimotor skills.
What is the striatum’s role in memory storage?
Habit-formation memories.
What did Hebb argue was the basis for long-term memory?
Changes in the efficiency of synaptic transmission.
What is long-term potentiation (LTP)?
High-frequency electrical stimulation to presynaptic neurons induced by synaptic transmission.
Why is LTP so widely studied?
Because they are very similar to Hebb’s theory of synaptic changes for long-term memory.
What are the two key properties of LTP?
- It can last for months if successful.
- Successfully develops only if postsynaptic firing follows presynaptic firing.
(Co-occurrence, a.k.a Hebb’s Postulate for Learning’)
What is the NMDA receptor?
- Receptor for glutamate
- Prominent at synapses, hence its significance for LTP.
NMDA receptors do not respond effectively unless 2 things co-occur…
- Glutamate is bound to the receptor.
- Postsynaptic neuron must already be partially depolarized.
Why is it important that postsynaptic neurons must already be partially depolarized for a successful LTP?
- Enables the generation of associations in the neural network. This is the foundation for a LTP to last.
What is long-term depression (LTD)?
- Opposite of LTD.
- Prolonged co-occurrence of low-frequency stimulation of presynaptic neurons.
Which amnesic patient seemed to provide strong evidence for the involvement of the hippocampus in memory?
R.B.
