Presentation on theme: "Chapter 9: Mechanisms of Learning Unit 4 – AOS 1 Learning Pages 422-451 1."— Presentation transcript:
Chapter 9: Mechanisms of Learning Unit 4 – AOS 1 Learning Pages 422-451 1
Study Design Content behaviours not dependent on learning including reflex action, fixed action patterns and behaviours due to physical growth and development (maturation) mechanisms of learning: – areas of the brain and neural pathways involved in learning, synapse formation, role of neurotransmitters – developmental plasticity and adaptive plasticity of the brain: changes to the brain in response to learning and experience; timing of experiences – use of imaging technologies in identification of localised changes in the brain due to learning specific tasks 2
3 Defining Learning Learning is such an integral part of daily living that without the ability to learn, people would be unable to live independently and would need constant care in order to survive. Learning can be defined as a relatively permanent change in behaviour that occurs as a result of experience.
4 Defining Learning It is an ongoing process which continues throughout the lifespan, enabling us to adapt and cope with an ever-changing world. Learning can occur intentionally or unintentionally. Learning can also occur actively or passively.
5 Defining Learning The notion of change is an important part of the definition of learning because something must be different about the organism after learning has taken place. The change in behaviour may be immediate (ie changing your golf swing after a coach suggests an improvement).
6 Defining Learning The change also may be delayed and actually occur some time after learning has taken place (ie changing your golf swing the next time you play golf after watching an instructional video). Consequently, learning refers to a change in behaviour potential as well as behaviour which is observed to take place.
7 Defining Learning Learned behaviour is also defined as being relatively permanent because it cannot simply be present at one moment and then disappear the next.
8 Behaviour not Dependent on Learning Although learning accounts for most of the behaviour of people and animals, not all behaviour has to be learned. Reflexes, fixed-action patterns and maturation also account for certain behaviours.
9 Reflex Actions Automatic or involuntary behaviour which does not require prior experience and is basically the same each time is called a reflex. We are born with a large number of reflexes, with each one allowing us to deal with certain stimuli that are important for our protection and survival.
10 Reflex Actions Some reflex actions that we have include: The suckling reflex The gripping reflex Blinking The knee jerk reflex The Babinski reflex Peripheral vision reflex Gagging reflex Fainting
11 Fixed Action Patterns A fixed-action pattern of behaviour occurs when different members of the same species produce and identical response to the same specific environmental stimuli. This type of behaviour is also referred to as species-specific behaviour.
12 Fixed Action Patterns The mechanisms that controls the behaviours are ‘fixed’ in that they are genetically programmed into the animals nervous system and appear to be unable to be changed as a result of learning. The term ‘fixed-action’ is used to describe behaviour that is inherited by every individual member of a species.
13 Fixed Action Patterns Fixed-action behaviour can also be sex-specific. Sex-specific behaviours are linked to courtship, sexual behaviour and nesting by male and/or female members of the species. Fixed-action patterns differ from reflexes in that they are more complex consisting of a sequence of responses.
14 Maturation Other unlearned behaviour is the result of maturation. Maturation is a developmental process leading towards maturity based on the orderly sequence of changes that occur in the nervous system and other bodily structures controlled by genetic inheritance. Learning Activity 9.1 – Learned versus non- learned behaviour, pg. 426 Learning Activity 9.2 – Review questions, pg. 427
Neural Basis of Learning When neurons communicate with each other, they do so by sending a neurotransmitter comprising of electrochemical messages across a tiny space between the neurons The gap between the axon terminal of one neuron (which releases the neurotransmitter) and the dendrite of another (which receives the transmitter is known as the synaptic gap The synapse contains three components; ◦ The synaptic gap ◦ The axon terminal of the presynaptic neuron ◦ The dendrite of the postsynaptic neuron The synapse is the site of communication between adjacent neurons and the act of sending neurotransmitter across the synaptic gap can actually change the synapse 15
Neural Basis of Learning A – Presynaptic Neuron B – Postsynaptic Neuron 2 – Neurotransmitter 4 – Synapse Direction of neural impulse 16
Neurotransmitters The site of chemical communication between neurons is, as we know, the synapse This small gap between the pre and post synaptic neurons is where electrical energy is converted into chemical energy to allow the impulse to continue When a neural impulse reaches the axon terminal in the presynaptic neuron, neurotransmitters (a chemical substance that enables communication between neurons) are released into the synapse from the axon terminal Each type of neurotransmitter has a distinctly different shape and role – there are believed to be over 100 different neurotransmitters Two of these are believed to involved in learning – glutamate and dopamine 17
Neural Basis of Learning Dendrites can grow longer and ‘sprout’ new branches while others can be ‘pruned’ away if not used – everyday we form and lose millions of synaptic connections The ability of the brain to change is commonly referred to as plasticity, a property that makes learning and memory possible and assists us to adapt to life’s every changing circumstances 18
Areas of the Brain and Neural Pathways involved in Learning Like memory, many areas of the brain are involved in learning although some areas seem to be more actively involved in certain types of learning Learning can involve the formation and strengthening of neural connections at the synapse – for example learning to play the piano will form new neural connections while regularly playing the piano will strengthen those connections 19
Areas of the Brain and Neural Pathways involved in Learning According to Hebb (1949), when a neurotransmitter is repeatedly sent across the synaptic gap, the presynaptic and postsynaptic neurons are repeatedly activated at the same time This has the effect of changing the chemistry at a synapse, leading to a strengthening of the connections between neurons at a synapse When the connection is strengthened, this makes the neurons more likely to fire together – when the connection is disused, it weakens and the neurons become less likely to fire together 20
Areas of the Brain and Neural Pathways involved in Learning The synaptic changes that take place within a neuron during learning are believed to have long-term potentiation Long-term potentiation refers to the long-lasting strengthening of the synaptic connections of neurons, resulting in the enhanced or more effective functioning of the neurons whenever they are activated The effect of LTP is to improve the ability of two neurons to communicate together Evidence of LTP – Morris and others (1982), Tsien (2000) Learning Activity 9.4 – Review questions, pg. 433 21
Plasticity and Effects of Experience on the Brain Plasticity refers to the ability of the brain’s neural structure or function to be changed by experience throughout a lifespan (plasticity meaning flexible or pliable) Some areas of the brain such as the sensory and motor cortices are more plastic than others but it is unclear whether all brain structures have this plasticity The brain of a developing individual has a much higher level of plasticity than that of an adult – this is one reason why children can learn much more quickly than an adult, a new language for example Effect of the environment on learning - Research by Roseweiz and others (1960s) 22
Developmental Plasticity and Adaptive Plasticity Some psychologists distinguish between various types of plasticity Developmental plasticity – occurs as the brain develops according to its genetics Adaptive plasticity – most apparent in recovery from brain trauma or injury 23
Developmental Plasticity Refers to changes in the brain’s neural structure in response to experience during its growth and development This type of plasticity is predetermined by our genes but can also be influenced by our environment After birth a significant developmental change occurs where the infant brain forms far more synaptic connections than it will ever use in a process known as synaptogenesis (the forming of new synapses) Synaptogenesis during an early age is believed to allow an infant to respond to the constant stream of new environmental input 24
Developmental Plasticity Following the development of all these new neural connections, the brain undertakes a process of eliminating these synaptic connections in a process known as synaptic pruning Synaptic pruning occurs in different rates in different areas of the brain but the number of synapses in an adult brain is 40% less than that of a three-year old brain 25
Developmental Plasticity The timing of experiences is also important in the plasticity of the brain These periods are called sensitive periods A sensitive period is a specific period of time in development where an organism is more responsive to certain environmental stimuli or experiences An example is in cats, monkeys and humans; if after birth one eye is kept closed or does not function properly due to an abnormality, that eye will be forever blind – this change responsible for the loss of vision occurs in the visual cortex 26
Adaptive Plasticity Adaptive plasticity refers to changes occurring in the brain’s neural structure to enable adjustment to experience, to compensate for lost function and/or to maximise remaining functions in the event of brain damage Generally adaptive plasticity allows the brain to compensate for damage by reorganising its structure At a neuronal level, two processes for recovery are rerouting and sprouting ◦ Rerouting involves an undamaged neuron which has lost an active connection with a neuron may seek a new connection with an active neuron ◦ Sprouting is the growth of new bushier nerve fibres with more branches to make new connections 27
Adaptive Plasticity Through adaptive plasticity, functions that are assigned to particular areas of the brain can sometimes be reassigned to other undamaged parts of the brain to compensate for changing input from the external environment Areas of the somatosensory cortex for example, can be reassigned to receive input from other areas of the body in the event of damage or in response to the environment The brain does not only demonstrate adaptive plasticity in response to damage – it also can be due to the environment Neuroimaging studies show that in violinists, the area of the somatosensory cortex that represents the fingers of the left hand (requiring fine finger control) is larger than the area the represents the right hand (using the bow) 28
Imagery in Learning Using neuroimagery techniques, it is possible to demonstrate the plasticity of the brain and brain areas When MRI scans of London cab drivers (who find new routes daily) are compared with London bus drivers (who follow a fixed route), they show that the rear part of the hippocampus of taxi drivers, which is involved in spatial awareness and memory, is significantly larger. Learning Activity 9.1 – Review questions, pg. 445 29