Neurophysiological processes of memory formation

Neurophysiological processes of memory formation

1. memory

   • Short term or long term storage & retrieval of new information in the brain
   • Memory refers to the processes in the nervous system that encode learning
   • Memory formation requires relatively permanent change (plasticity) in the brain – at the level of single neurons and synaptic membranes
   • Memories can last for as little as half second to as long as a lifetime

2. Aplysia

   • Has only 20,000 neurons (compared to around one trillion in humans)  Very large nerve cells– visible to naked eye  Arranged in small groups capable of simple learning  Aplysia is capable of various forms of learning observed in humans such as habituation and classical conditioning
   • If the siphon is repeatedly touched the animal habituates, i.e. it learns to ignore it and shows a reduced behavioural response (less gill withdrawal)

3. synapses

   • connection between 2 neuron
   • 1. neurotransmitters realeased from axonal terminal of presynaptic cell
     • 2 - binds receptions to ion channels of postsynaptic cell
       • ions start to move and effect the the postsynaptic membrane

4. Plasticity Opportunities

   • Short term:  Change the amount of transmitter released  Change the time transmitter spends in the cleft
   • Long term:  Change the number of receptors (channels)  Change the number of synapses
   • hebb Proposed that when memories are formed, a structural change takes place at the synapse •“Cells that fire together, wire together”: there is an increase in synaptic efficacy when the pre-synaptic cell repeatedly stimulates the postsynaptic cell