Learning Theories and Types

• A relatively enduring change in behaviour results from experience, improving event prediction and environmental preparedness.

Learning Theory

• The psychodynamic approach emphasizes unconscious mental processes, using introspection to examine thoughts and emotions.
• The behaviourist approach emphasizes environmental influences and focuses on observable behaviour as a valid measure.

Types of Learning

• Non-associative learning involves a change in behaviour after repeated or continuous stimulus exposure.
  • Habituation refers to a decrease in behavioral response after repeated stimulus exposure.
  • Dishabituation refers to an increased response due to a change in a familiar stimulus.
  • Sensitization refers to an increased response after exposure to a threatening stimulus, resulting in a heightened response.

Aplysia Californica

• Gill withdrawal in aplysia demonstrates non-associative learning.
  • Habituation occurs with repeated, harmless siphon stimulation, weakening the gill withdrawal response due to reduced neurotransmitter release in motor neurons.
  • Sensitization occurs when a strong stimulus, such as a tail shock, increases neurotransmitter release, making the gill withdrawal more pronounced.
    • Short-term habituation involves response recovery after a short break.
    • Long-term habituation involves a response remaining reduced with minimal recovery after repeated exposure over several days.
• Observational learning involves learning by watching or imitating.
• Associative learning involves learning the connection between two pieces of information through classical and operant conditioning.
  • The unconditioned stimulus (US) naturally triggers a response, such as food.
  • The unconditioned response (UR) is an automatic reaction to the US, such as salivation to food.
  • A conditioned stimulus (CS) is a previously neutral stimulus that elicits a response after association with the US, such as a bell.
  • The conditioned response (CR) is the learned response to the CS, such as salivation to the bell.

Classical Conditioning Processes

• Acquisition involves repeatedly pairing the CS and US, leading to the CR.
• Extinction involves the CR weakening and eventually disappearing if the CS is repeatedly presented without the US.
• Spontaneous recovery involves the CR reappearing if the CS is presented again after a rest period, though usually weaker.

Second Order Conditioning

• A neutral stimulus paired with the CS can elicit the CR without direct exposure to the US.
  • For example, a light paired with a bell causes a dog to salivate at the sight of the light alone.
• Associating money with happiness: Money can be associated with happiness because it is linked to experiences that are pleasurable.
• Stimulus generalization involves similar stimuli producing the CR and is adaptive.
• Stimulus discrimination enables animals to differentiate between similar stimuli, responding only when the stimulus is paired with the US.
  • A dog learns to discriminate between similar bells, salivating only to the original tone if similar bells are played without food.
• Phobia is an acquired fear disproportionate to the real threat, developed through fear experience generalization via fear conditioning.
  • The amygdala processes fear responses triggered by specific stimuli.
  • The hippocampus encodes context-dependent fear tied to environment or situation.

Operant Conditioning

• Behaviour is influenced by consequences, such as rewards or punishments.
• Thorndike’s law of effect states behaviours followed by satisfying outcomes are more likely to be repeated (reinforcement) while unwanted behaviours are less likely to be repeated.
  • In a Skinner box, rabbits could press a lever to reveal food or avoid a mild shock.
• Shaping is the process of reinforcing behaviours that are increasingly similar to the desired behaviours..
• Primary reinforcers are biological needs and inherently reinforcing because they are essential for survival e.g food, water, and sleep.
• Secondary reinforcers are learned through classical conditioning by associating with primary reinforcers.
  • According to the Premack principle, a more valued activity can reinforce a less valued activity.
• Continuous reinforcement involves reinforcing every desired behaviour, leading to fast learning but quick extinction.
• Partial reinforcement involves reinforcing behaviour only some of the time, leading to slower learning but greater resistance to extinction.
  • Fixed interval reinforcement occurs after a set amount of time.
  • Variable interval reinforcement occurs irregularly.
  • Fixed ratio reinforcement occurs after a set number of behaviours.
  • Variable ratio reinforcement occurs after a variable number of behaviours.

Positive and Negative Reinforcement

• Reinforcement - Increase behaviour
  • Positive Reinforcement - Add something pleasant
  • Negative Reinforcement - Remove somethine unpleasant.
• Punishment - Decrease behavior
  • Positive Punishment - Add something unpleasant
  • Negative Punishment - Remove something pleasant.

Observational Learning

• Observational learning is a social learning and adaptive tool to learn what is safe versus dangerous and to learn language and cultural beliefs.
• Modelling (Demonstration and Imitation)
  • Modelling is more likely to occur when imitating model that are attractive, high status, and similar to us.
  • Often implicit (unconscious). Only effective if observer physically capable of imitating the behaviour.
• Vicarious learning and reinforcement occurs by learning behaviours by observing others being rewarded or punished.
  • Lab-raised monkeys, with no fear of snakes, learned fear by observing wild monkeys' fearful reactions.

Learning and Memory

• Learning is the process of acquiring new information, while memory is the persistence of learning in a state that can be revealed later.
• Memory can fail due to amnesia, head injury, psychological trauma, disease, dementia, or Korsakoff’s syndrome.

Alzheimers disease

• Most common form of dementia, primarily affecting older adults.
• Linked causes
  • Acetylcholine deficiency affecting memory and cognition
  • Amyloid plaques disrupting cell function
  • Neurofibrillary tangles damaging neuron structure

Memory Processes

• Encoding converts sensory input into short-term memory.
• Storage consolidates short-term memory into long-term storage.
• Retrieval accesses stored information to guide behaviour.

Memory Types

• Sensory memory involves brief storage of sensory input.
  • Iconic for visual, echoic for auditory
• Short-term memory (STM) temporarily holds limited information.
• Working memory is part of STM for active information processing.
• Long-term memory (LTM) is for large, enduring information storage.
• Reconsolidation is reactivation of memories from LTM to working memory which requires reconsolidation to be stored again, it can be altered and evolved over time.

Long Term Memory

• Explicit memory includes episodic memory (experienced events) and semantic memory (knowledge and concepts).
• Implicit memory includes procedural memory (skills and actions) and emotional conditioning.
• Emotional memories are stored separately from factual details.

H.M Anterograde Amnesia

• Removal of parts of medial temporal lobes resulted in H.M losing the ability to form new explicit memories, but retained past memories and procedural learning.

H.M.'s case revealed four key principles about memory:

• Different types of memory exist: H.M could learn motor skills (implicit memory) despite losing the ability to form new explicit memories.
• The medial temporal lobe is crucial for new explicit memories: H.M’s damage affected memory formation but not intelligence or perception.
• Working memory is separate from long-term memory: H.M could maintain attention and rehearse information but couldn't transfer it to long-term storage.
• Long-term memories are stored elsewhere: H.M’s past memories remained intact, suggesting the medial temporal lobe is not the final storage site.
• Lashley and the engram: memory is distributed rather than localized, and include amygdala, hippocampus, cerebellum, prefrontal cortex.

Neuronal Remodelling

• "Neurons that fire together, wire together.”
• When presynaptic and postsynaptic neurons are repeatedly activated together, their synaptic connection strengthens.
• Cell assemblies: network of neurons that store information and support learning/memory.
• Hebb’s postulate: “When an axon of cell A excites cell B and repeatedly takes part in firing it, some growth process takes place so that A’s efficiency as one of the cells firing B is increased.”

Synaptic Basis of Memory

• Memories are stored in networks of interconnected neurons and modify due to plasticity, synaptic changes, and hippocampus.
• Long-term potentiation (LTP) refers to a lasting increase in synaptic strength.
  • LTP occurs in the hippocampal formation, including the hippocampus, dentate gyrus, and subiculum.
    • Perforant pathway connects the entorhinal cortex through the subiculum to the dentate gyrus.
    • Mossy fibres connect the dentate gyrus to CA3 pyramidal cells.
    • Schaffer collateral pathway connects CA3 pyramidal cells to CA1 pyramidal cells.
• LTP strengthens synapses.
• Weak stimulating of electrodes resulted in stable EPSP's.
• Tetanus stimulation resulted in larger EPSP's improving learning and memory.
• Increased neurotransmitter release in the stimulated presynaptic terminal increases dendritic spine and thickness.

Chemical Basis of LTP

• LTP relies on glutamate.
• glutamate is released and binds to ionotropic receptors, activating ligand-gated ion channels to strengthen synaptic connections.

Pharmacological Inhibition of LTP

• LTP can be pharmacologically inhibited using NMDA receptor antagonists, such as Amino-Phosphono-Valeric Acid (APV) blocking NMDA receptors and preventing synaptic strengthening.
• Glutamate binding to NMDA receptors is essential for inducing LTP.