Cellular basis of learning Flashcards
habituation (general terms)
-when a stimulus is repeated over a period of time, the response diminishes
“decreasing response to a sensory stimulus”
sensitization (general terms)
-an increased response to the same stimulus that previously underwent habituation
“increasing response to a sensory stimulus”
molecular basis of habituation
- repeated stimulation
- depletes the supply of NT (Glu)
- less Glu is released
- less depolarization
- motor neuron is not stimulated
- decreased gill withdrawal reflex
molecular basis of short term sensitization
- shock
- interneuron releases 5HT
- sensory neuron phosphorylates proteins (pka)
- K+ and Ca++ channels on sensory neurons open up
- influx of Ca++ causes release of NT (Glu)
- motor neuron is stimulated again
molecular basis of long term sensitization
- multiple repeated shocks
- interneuron releases 5HT
- sensory neuron phosphorylates proteins (pka)
- PKA triggers PROTEIN SYNTHESIS (changes genes)
- change in gene expression supports a long-lasting increase in NT release
types of learning
- habituation
- sensitization
- associative conditioning
associative conditioning
- associating two sensory stimuli
- aka Pavlovian conditioning
- leads to formation of an associative memory
-when remove the natural stimulus, the artificial stimulus still brings the response
removal of hippocampus
-no ability to form new memories
synapses in hippocampus
- dentate gyrus to CA3 pyramidal cell
- to CA1 pyramidal cell
- to cortical regions
- this section focuses in CA1 region
LTP is induced by __________
LTP is induced by HIGH FREQUENCY STIMULATION
NMDA receptor channel only opens when post-synaptic neuron is ________
NMDA receptor channel only opens when post-synaptic neuron is DEPOLARIZED
molecular basis of the trigger of LTP
- stimulation of AMPA receptors allows Na+ to flow into cell
- Mg+ blocks NMDA receptor
- with repeated stimulation, there are larger, stronger reactions to Na+
- Mg+ is expelled from NMDA receptor
- Ca++ enters cell
- signalling cascade
- LTP
molecular mechanisms underlying EARLY LTP
- increase in Ca influx (due to opened NMDA receptors)
- activation of protein kinases (PKC, calmodulin)
- phosphorylation of receptors (AMPA)
- phosphorylated AMPA is inserted into membrane to increase
PROTEIN PHOSPHORYLATION
early LTP
- lasts 1 to 2 hours
- caused by single 100 Hz high frequency stimulation
- cellular basis of short term memory
late LTP
- lasts days to weeks
- caused by multiple high frequency stimulations
- cellular basis of long term memory
