LEARNING
NEURAL BASIS OF LEARNING AND MEMORY
NEUROTRANSMITTERS + NEUROHORMONES
CLASSICAL CONDITIONING
OPERANT CONDITIONING
OBSERVATIONAL LEARNING
Neural Plasticity
The ability of the brain's neural structure and function to be changed by experience through the lifespan. Younger brains have higher plasticity.
Synaptic Plasticity
The ability of the synapse to change over time
Hebb's Rule
Neurons that fire together wire together. Proposed that learning results in the creation of cell assemblies, interconnected groups of neurons that form networks or pathways.
- When a neurotransmitter is repeatedly sent across the synaptic gap, pre and postsynaptic neurons are repeatedly activated at the same time.
- This changes the structure of the synapse, strengthening the connection between these two neurons at the synapse.
- When this connection is strengthened they are more likely to fire together again, and there signals are more efficient in the future.
Long-Term Potentiation (LTP)
The long-lasting strengthening of synaptic connections, resulting in enhanced or more effective synaptic transmission. This improves the ability of two neurons to communicate with each other.
Long-Term Depression (LDP)
The opposite of LTP, a long lasting decrease in the strength of synaptic transmission. Results from a lack of stimulation of pre and postsynaptic neurons or prolonged low level stimulation.
Neurohormones
Like neurotransmitters, neurohormones are chemical messengers that are manufactured by neurons and released from the axon terminal.
Neurotransmitter vs Neurohormones Communication
Neurotransmitters are secreted into the synaptic gap and deliver their message to the postsynaptic neuron.
Neurohormones are secreted into the blood for transport to target cells.
Role of Glutamate in Synaptic Plasticity
Glutamate plays crucial roles in the synaptic changes that occur and given its excitatory effect has a vital role in LTP and LTD. It promotes the growth and strengthening of synaptic connections between neurons. The more often that glutamate can excite an adjacent neuron, the more it contributes to LTP.
Consolidation
The biological process of making a newly formed memory stable and enduring after learning. Time is required after learning takes place for the information to consolidate as a durable long term memory. If consolidation is disrupted (e.g. from a severe blow to the head), new info may not transfer from short to long term memory, or it will not be stored well if it arrive there.
Interruption to Consolidation
People who have experienced brain trauma can experience memory failure or loss and are frequently unable to report any memory of the events immediately before the incident and often can't remember 30 minutes before the trauma.
Consolidation and Reconsolidation
The hippocampus has a crucial role in the consolidation of most of our memories. Once consolidated, memories are not necessarily fixed. Whenever a memory is retrieved, it is open to further consolidation and has to be re-stabilised through reconsolidation.
Adrenaline
Adrenaline can enhance the consolidation of long-term memories of emotionally arousing experiences meaning these events are more likely to be well remembered (but not necessarily more accurately). Significant stress-inducing experiences create memories that are lasting, vivid and highly detailed. When released during heightened emotional arousal, adrenaline induces the release of noradrenaline in the amygdala. It is believed that the presence of noradrenaline during consolidation may signal to the hippocampus that details of the relevant experience are significant and its long-term storage should be strengthened.
A type of learning that occurs through the repeated association of two different stimuli. Learning only occurs when a particular stimulus consistently produces a response that it did not previously produce. A response is automatically produced by a stimulus that becomes associated with another stimulus that would not normally produce this response.
Three Phase Process
Before Conditioning
- NS produces no relevant response
- UCS elicits the UCR
During Conditioning - NS is repeatedly paired with the UCS to produce the UCR
After Conditioning - NS becomes a CS
- CS produces a CR which is usually similar to the UCS
Trials, Acquisition and Timing
- Each paired presentation of the NS with the UCS is referred to as a trial
- Acquisition describes the overall process during which an organism learns to associate the NS and the UCS until the NS alone has become a CS that produces the CR
- An important consideration is the timing of the NS and UCS pairing, the NS should be presented before the UCS and there should be very short time between their presentations
Stimulus Generalisation
The tendency for another stimulus that is similar to the CS to produce a response that is similar, but not necessarily identical, to the CR
Stimulus Discrimination
Occurs when a person or animal responds to the CS only, but not to any other stimulus that is similar to the CS
Extinction
The gradual decrease in the strength of rate of a CR that occurs when the UCS is no longer presented.
Spontaneous Recovery
The reappearance of a CR when the CS is presented, following a rest period after the CR appears to have been extinguished. Does not always occur.
A type of learning whereby the consequences of behaviour determine the likelihood that it will be perofrmed again in the future
Three-Phase Mode
Antecedent (A)
- Stimulus that occurs before the behaviour
Behaviour (B) - Occurs due to the antecedent
Consequence (C) - Consequence to the behaviour
Reinforcement
When a stimulus strengthens or increases the frequency or likelihood of a response that it follows, strengthens behaviour
Positive Reinforcement
Giving or applying a positive reinforcer after the desired response has been made
Negative Reinforcement
Removal or avoidance of an unpleasant stimulus
Punishment
Decreases the likelihood of a response that it follows, weakens behaviour
Positive Punishment
Giving a negative punishment after an undesired response has been elicited
Negative Punishment
Removal of a pleasant stimulus
Response Cost
The removal of any valued stimulus, whether or not the stimulus causes the behaviour. There is a cost for your response.
Stimulus Generalisation
The correct response is made to another stimulus that is similar (but not identical) to the stimulus that was present when the conditioned response was reinforced
Stimulus Discrimination
When an organism makes the correct response to a stimulus and is reinforced, but does not respond to any other stimulus, even when they are similar
Extinction
Gradual decrease in the strength of frequency of the response following consistent non-reinforcement
Spontaneous Recovery
Organism will once again show the response in the absence of a reinforcer (after it has been extinct)
Occurs when someone uses observations of a model's actions and the consequences of their actions to guide their future actions.
- Model: who/what is being observed
- Live Model: real-life person who is demonstrating
- Symbolic Model: real or fictional model who is displaying behaviour in books, movie etc.
Observational Learning as Conditioning
Involves being conditioned indirectly by observing someone else's conditioning, so can be called vicarious conditioning. The individual watches a model's behaviour either being reinforced or punished, and then is more or less likely to behave that way themselves.
Stages of Observational Learning
- Attention: In order to learn through observation, we must be paying attention to or closely watch a model's behaviour and the consequences.
- Retention: Having observed the model, and paid attention to the behaviour, we now must remember the model's behaviour
- Reproduction: When the models behaviour has been closely watched, and remembered, we can attempt to reproduce, or imitate, what has been observed. We must have the ability to be able to be able to produce the behaviour that we have observed
- Motivation: If we have watched and remembered and are able to reproduce the behaviour, we now have to be motivated to reproduce it
- Reinforcement: Unless the behaviour is useful or is reinforced, we are unlikely to imitate it