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The Neural Basis of Learning and Memory (What is Learning (Defined as a…
The Neural Basis of Learning and Memory
What is Learning
Defined as a "relatively permanent change in behaviour due to experience". Learning begins at birth and continues through life. Learning go hand-in-hand. Memory is defined as "an active information processing system that receives, organises, stores and recovers information".
Neural Plasticity in L+M
The way the brain changes in response to stimulation from the environment. The synapses within the brain are modified. Neural connections are formed, removed, and remade continuously as you learn new things and form new memories. the precise way that this occurs is not fully understood. The process happens more easily when you are young.
Developmental Plasticity
Changes to the brain that occur more frequently in the foetal stage, in childhood and adolescence
Adaptive Plasticity
Changes to the brain, primarily association areas that occur due to developing synapses through learning and memory. Also accounts for changes that are made to repair damage to the brain. Neural plasticity can occur in 3 mechanisms:
One:
By modifying an existing synapse -
Two:
By producing new synaptic connections -
Three:
By changing the excitability properties of a neuron
Long-term Potentiation
The number of neurons in our brain does not change much once we reach adulthood. However, the number and strength of synaptic connections can change. This is a form of neural plasticity. LTP is the "increased tendencies of a group of neurons to fire together after they have been electrically stimulated at a particular electrical frequency". The connection between neurons is strengthened and there is an increased release of neurotransmitters, increased receptor sensitivity and changes to the structure of the synapse
Neurotransmitters and Neurohormones
A
neurotransmitter
is a chemical messenger synthesised within a pre-synaptic neuron and transmitter across the synapse. A
neurohormone
is a chemical synthesised in the neuron that is secreted directly into the bloodstream to act on a distant site. A
hormone
is a chemical produced in the glands and secreted directly into the bloodstream to act on a distant site
Long-term Depression
Opposite of LTP, long-term depression occurs when synapses become weaker. When electrical stimulation becomes less frequent, the synapse is weakened. It is possible that this is the mechanism by which unused memories are removed to make room for new or modified memories
Synapse Formation
LTP results in new synapses or stronger synapses. When new synapse form, we call this synaptogenesis. When learning occurs, the neurotransmitter glutamate is released into the synapse. This initiates new connections with the post-synaptic neuron. Small "sprouts" or "filagree appendage" grow between the pre-synaptic axon terminal and the post-synaptic dendrites. This allows information to be transferred. The more often this connection is used, the stronger the learning will be
Glutamate and Synaptic Plasticity
New experience
→
Glutamate released (AMPA + NMDA receptors must be present)
→
Dopamine released (Dendrite spines grow, increased sensitivity of neuron)
Consolidation
If the process of forming memory is disrupted, then the memory may not form. The hippocampus has a key role in consolidation memories
Adrenaline and Emotional Arousal
Adrenaline, when released very close to learning, helps to form (consolidate) the memory. Highly emotional situations, accompanied by adrenaline release, can result in strong memories. This can be counter productive if the situation where learning occurs is highly traumatic and can lead to post-traumatic stress disorder (PTSD). PTSD can result in sleep disturbances, flashbacks and intrusive visual images.
The Amygdala
The part of the brain associated with emotions, particularly fear. It also plays a crucial role in the formation of emotionally arousing memories.
Adrenaline and Consolidation
Adrenaline stimulates noradrenaline release
→
Noradrenaline stimulates the amygdala
→
Amygdala signals to the hippocampus to strengthen memory
Adrenaline and Flashbulb Memories
A flashbulb memory is a detailed and long-lasting memory of an important or emotional event. Research suggests adrenaline is released at the time of the memory formation and enhances the memory