Learning and Memory Flashcards
1
Q
What is Habituation?
A
- response to stimulus gradually gets smaller over time
- ex) if you turn on the fan in a room, you will initially hear it and eventually you don’t hear it anymore
2
Q
What is sensitization?
A
- the opposite of habituation
- response to a stimulus increase over time
- ex) after a bumpy plan ride, you may be a little jumpy for a while
3
Q
Neural Mechanisms of learning
A
- larger neurons and fewer neurons make it a good animal to study
- largely studied in aplysia californica
4
Q
What is the gill-withdrawal reflex?
A
- the gill is used for breathing
- the gill is covered with the mantle shelf
- waste and seawater are released through siphon
- touching the siphon leads to a retraction of the gill
5
Q
What is the habituation in the gill-withdrawal reflex?
A
- touching the siphon repeatedly leads to less of a reflex/retraction of the gill
- what would this be?
- either sensory neurons are becoming less responsive
- motor neurons are becoming fatigued or changes occur between the sensory and motor neurons
6
Q
What is habituation explained?
A
- single cell recordings show that sensory neurons do not decrease activity with each touch of the siphon
- electrical stimulation of the gill’s motor neurons show that it can still contract after being habituated
7
Q
Changes in hibituation explaned
A
- so, changes must be occurring between the sensory and motor neurons
- repeated siphon touches leads to less calcium into the sensory neurons which means less neurotransmitter is being released into the synapse
- smaller EPSP’s occur in interneurons and motor neurons ~ leads to a smaller gill withdrawal
8
Q
What is sensitization in siphon?
A
- after an electrical shock to the head or tail, aplysia show an increased gill-withdrawal response
- sensory neurons release more neurotransmitter onto the interneurons and motor neurons which to leads to the larger response
9
Q
Long term changes observed
A
- normal aplysia showed 1300 axon terminals synapsed with sensory neurons
- those that experienced sensitization had 2800 terminals
- those that experienced habituation had 800 terminals
10
Q
long term potentiation
A
- a long lasting strengthening of a synapse
- more NT is released with any input
- thought to be associated with memory formation
LONG TERM DEPRESSION: a weakening of a synapse that lasts hours or days ~ thought to be associated with learned
11
Q
What are the cellular mechanism for LTP?
A
- NMDA and AMPA receptors
12
Q
What does NMDA and AMPA receptors do?
A
- they both are receptors for glutamate
- normally just NMDA receptors are available to depolarize the postsynaptic membrane
- when the connection is strengthened, AMPA are added to the membrane
- allows for the postsynaptic membrane to be depolarized easier ~ leads to LTP
13
Q
Is LTP the mechanism for long term memory?
A
- both can last indefinitely
- both can result from very brief input
- LTP is consistent with models proposed by Donald Hebb
- LTP is found in cells thought to be associated with memory formation like the hippocampus and the cerebellum
- MNDA receptors (that have been linked to memory) are also linked to LTP
14
Q
What about brain structures in learning?
A
- Hippocampus and the temporal lobe
- thalamus ~ Papez’s Circuit
- prefrontal cortex
- basal ganglia
- cerebellum
15
Q
What happened with patient H.M.?
A
- large areas of H.M.s hippocampi and temporal lobes were surgically removed
- personality and IQ were not impacted and experienced profound anterograde amnesia