Mechanisms of memory & learning

Mechanisms of memory & learning

1. Memory = is the retention of learning information.

   • Learning = is the aqcuisition of new information or knowledge

2. Habituation

   • Learning to ignore stimulus that lacks meaning i.e. background noise

3. Sensitisation

   • Learning to intensify response to stimuli that previously evoked little response i.e. constant beeping (strong stimulus) inceases reaction (by getting agitated) to all other stimuli

4. 1. Non-Associative Learning

5. 2. Associative Learning

   • Classical Conditioning
     • Instrumental Conditioning
       • Learning to associate a response with a meaningful stimulus e.g. reward lever pressing for food.= motivation
     • Pair an unconditional stimulus (IC) with a conditional stimulus (CS) to get a conditioned response (CR)

6. Invertebrate Models of Learning

   • Sensitisation
     • Generalisation of aversive stimulus (shock) response to other stimuli (i.e. water jet)
       • Sensitisation over repeated water jet (increased gill-reflex response)
         • PKA is activated by g-protein & its activation shuts down K+ channels - prolongs the action potential in sensory neuron. V-G Ca2+ channels open for longer = increasing duration of NT release (exagerated Gill-reflex response)
           • Sensitisation is because of blockage of the V-G potassium channels!!!
   • Habituation
     • Habituation over repeated water jet (decreased gill-reflex response)
       • Plasticity - changes to the synapse on response to changing environments
         • Repeated water jets = deactivation of V-G Ca2+ channels (decreasing calcium influx/decreasing NT exocytosis = stops activation of gill-reflex response
           • NB: V-G Calcium channels open up when voltage positive inside (when above zero)
             • If potassium is deactivated (& the K+ channels blocked - potassium cant move), the falling phase cant happen as quickly.
               • There is therefore delay before potassium flows out (time that the cell is positive on the inside is extended out)
                 • This means that the voltage-gated calcium channels are open longer and there is more neuro-transmitter release
                   • More calcium = more transmitter release via exocytosis
       • Repeated electrical stimulation of a sensory neuron leads to a progressively smaller EPSP in the postsynaptic motor neuron
   • Water jet to siphon = gill-withdrawal reflex