NSCI 300: lab 7

neuroplasticity

ability of neurons and neural networks to change or adapt due to experience

types of neuroplasticity

1. functional

2. structural

functional neuroplasticity

change location of function from 1 brain area to another

Hebbian theory of learning

• cells that fire tgt wire tgt

• when 2 neurons are activated simultaneously, the synapse between them becomes more efficient

associative learning

• classical conditioning

• operant conditioning: punishment and reward

non-associative learning

• habituation

• sensitization

habituation

• negative memory

• brain ignore signals

sensitization

• positive memory

• brain cannot ignore signals

mantel shelf

covers the gill to protect it

siphon

• tube-like structure

• guide water to tail

parapodium

• wing-like structure

• further protects respiratory apparatus

Why Aplysia?

• simple nervous system

• large nerve cell bodies

• consistent location of individual neurons from one animal to another

• capable for various behaviours and simple forms of learning

habituation aplysia response

• siphon-induced gill withdrawal reflex

• decreased response of gill withdrawal

possible mechanisms underlying habituation

1. muscle fatigue

2. decrease in motor synapse

3. loss of skin sensitivity

4. decrease in synaptic transmission

Muscle fatigue?

decrease in motor synapse?

intracellular stimulation of the same motor neuron that caused gill withdrawal before habituation still resulted in a gill response after habituation occurred

loss of skin sensitivity?

• intracellular recordings directly from the gill motor neuron before and after habituation

• nerve containing sensory axon was blocked temporarily by decreasing extracellular Na+ concentration, so it’s not enough to trigger AP

• WHATT??

decrease in synaptic transmission

quantal analysis revealed amount of glutamate released from presynaptic terminal of sensory neurons decrease

sensitization aplysia response

• siphon-induced gill withdrawal reflex

• electric shock given

• increased response after shock given = more powerful withdrawal

sensitization depends on:

• age of animal

• intensity of stimulus

• frequency of exposure of stimulus

bad trials

• natural gill movement or reflexes

• touched a diff part of the siphon

• double pump (siphon/gill)

• variations in intensity or speed of touching the siphon

why is touching a diff part of the siphon problematic?

• has 24 sensory neurons

• could activate diff sensory neuron if touched diff part

limitation

• need 3 animals to make conclusion but not realistic

• time restraint: 3-hour lab