Neuroplasticity + synaptic pruning PDF

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Neuroplasticity Explain the role of synaptic pruning in human behaviour Explain neuroplasticity, using one relevant piece of research to support your answer. Discuss one effect of the environment on physiological processes. SYNAPTIC PRUNING Our brains are hard-wired to take in the ever-changing array of stimuli that surrounds us, and which assaults our senses on a daily basis. Synaptic pruning is the process carried out in the brain to increase its efficiency: neurons and synaptic connections that are no longer used are eliminated. synaptic pruning plays a significant role in human behaviour and is part of neuroplasticity or the brains ability to remove and reduce neural networks and synapses in the brain that are not frequently travelled while pathways and synapses used often are strengthened. This shows that when learning a new skill, new neural networks were created. However, when the behaviour stopped, and those neurons were no longer activated the neurons were pruned. Researchers hypothesized that synaptic pruning is a way to increase efficiency of the brain. Synaptic pruning is often reflected in neuroimaging data as an increase or decrease in grey matter Which is the soma and dendrites of neurons. Maguire 2000 and Fuhrman et. al 2015. Fuhrman et. al 2015. -

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Plasticity describes the ability of the nervous system to adapt its structure and function in response to environmental demands, experiences, and physiological changes [6]. The human brain retains a baseline level of plasticity throughout life – this is known as experience-dependent plasticity and underlies all learning [7]. Plasticity during sensitive periods, by contrast, is experience-expectant – an organism ‘expects’ to be exposed to a particular stimulus during this time [7]. Adolescent plasticity might differ from plasticity early in development because, unlike babies and young children, adolescents are more likely and able to actively choose the environmental stimuli they experience. Generally, during childhood, environments are more structured by parents or caregivers, while adolescents have more autonomy to choose what to experience and with whom [25].

NEUROPLASTICITY This essay will attempt to give a brief summary on neuroplasticity, which will be supported by the studies carried out by Maguire (2002) and Draganski et al (2004). It used to be thought that brain development and change occurred only in childhood and that the brain of an adult was fixed and unchangeable. However, this is now known not to be the case, and neuroscientists call this ability to change and regenerate at all life stages ‘neuroplasticity.’ Neuroplasticity can formally be defined as the ability of the nervous system, especially the brain, to adapt to the environment and to replace function following damage. As we learn, we forge pathways through the brain and as we repeat the action or thought, the pathways become more robust; essentially they become our preferred route. However, it is possible to change our habits and thought patterns, and this is done through neuroplasticity. Neuroplasticity can occur when there has been damage. This happens in several ways; - Increased brain stimulation is when an area that lies close to the damaged area or has a similar function on the opposite hemisphere, is stimulated by practising other tasks that use that area specifically. - Axon Sprouting is when the link between two neurons is severed by damage, but other neurons connected in the same way sprout extra connections. This compensates for the lost connections and re-establishes a strong link. - Denervation supersensitivity activates neurons with the same function, meaning the functionality is increased. These three ways that neuroplasticity occurs mean that recovery is possible following trauma to the brain and that full recovery can be possible, in some cases. Apart from the function of adapting to damage and injury, neuroplasticity is the biological mechanism of learning. Draganski et al (2004) showed that there was a structural change in the brain in response to a simple learning routine such as practising juggling periodically. Maguire et al (2000) looked at the human neuroplasticity in a natural setting and demonstrated that London Taxi Drivers experience significant changes in the relative distribution of grey matter in the hippocampus in response to the demands of the job. Both these studies will be discussed further into the essay. (refer to notes for Maguire study)

This study demonstrates the effect of enrichment (in the form of juggling) on brain plasticity in participants who juggled. The research studies outlined above demonstrates that the more a person performs a particular activity, the more neural connections are formed in the area of the brain responsible, creating a physical change in the brain. This represents the bidirectional relationship between the environment and physiological processes occurring in the brain. EFFECT OF ENVIRONMENT ON PHYSIOLOGICAL PROCESSES This essay will attempt to offer a considered and balanced review that includes a range of arguments, factors and hypotheses on one effect of the environment on physiological processes, supported by research studies which investigate both effects. It is said that certain effects of the environment can affect physiological processes such as that of the human brain. Therefore, the relationship between the environment and physiology is often said to be ‘bidirectional’ where environmental enrichment changes the cerebral cortex and therefore the brain changes our experiences and behaviour. Adolescent plasticity might differ from plasticity early in development because, unlike babies and young children, adolescents are more likely and able to actively choose the environmental stimuli they experience. Generally, during childhood, environments are more structured by parents or caregivers, while adolescents have more autonomy to choose what to experience and with whom [25]. The effect of the environment on physiological processes that will be discussed include: - Enrichment of certain environments on brain plasticity

The brain's ability to rearrange its connections with its neurons; that is the changes that occur in the structure of the brain as a result of learning or experience (exposure to different environments). The changes that can take place are related to the challenges of the environment and thus represent an adaptation to it. Brain plasticity, or neuroplasticity, is the lifelong ability of the brain to reorganize neural pathways based on new experiences. o The brain has the ability to reorganise itself and form new connections between neurons. o It is stimulated by the environment. o Plasticity occurs every time something new is learnt o Brain plasticity is explicitly shown after brain injury when the brain reorganizes and forms new connections with healthy neurons to compensate for the functions of the damaged area. Supporting Study 1: Rosenzweig & Bennett (1972) Introduce Study - Connection of study to question • An example of a study which investigates the effects of a deprived or enriched environment on neuroplasticity is an experiment conducted by Rosenzweig and Bennet (1972). Aim: • To investigate the effects of a deprived or enriched environment on neuroplasticity, in particular, the development of neurons in the cerebral cortex. Method: • The participants used were rats (unspecified type). • The independent variable was the type of environment that the rats were exposed to. o Stimulating environment contained interesting toys o Deprived environment had no toys • The dependent variable was the weight of the rats? brains, showing the amount of brain plasticity that occurred in the rats. • The rats were separated and exposed to the two environments for 30-60 days before being euthanized. Results: • Rats in the stimulating environment had a thicker cortex and heavier frontal lobe (associated with thinking, planning, and decision-making) compared to rats in the deprived environment. Conclusion: • This may have resulted from the exposure to the toys in the stimulating environment, which helped to develop neural connections in the rat’s brain. Connection of study to question • This study showed the effect of the environment on physiology because more enriched environments helped develop neurons in brains of the rats. Supporting Study 2: Gaser and Schlaug (2003) Introduce Study - Connection of study to question: • Another example of another study investigating the effects of a deprived or enriched environment on neuroplasticity is a study conducted by Gaser and Schlaug (2003). Method: • Compared the brains of professional musicians (who practice at least 1 hr. a day) Results:

Grey matter volume was: highest in the professionals' brains o lowest in the non-musicians ▪ in several brain areas involved in playing music such as motor regions, anterior superior parietal areas and inferior temporal areas Connection of study to question • This study shows how environmental enrichment (in the form of music) contributes to neural connections in the brain – demonstrating brain plasticity. Supporting Study 3: Draganski et al. (2004) Introduce Study - Connection of study to question: • Another example of a study investigating environmental enrichment on brain plasticity is an study conducted by Draganski et al. (2004) Aim: • To determine whether functional and structural changes could be detected in the human brain as a result of learning a new motor skill Method: • 21 females and 3 males were split into two groups o One group had to spend 3 months learning a juggling routine for a minimum of 60 seconds, then spend 3 months not practising juggling Results: • MRI scans showed no structural differences in groups' brains before juggling. • There was an increase in volume of two regions of the jugglers' brains associated with the retention of visually detected movement information of learning o This difference decreased after 3 months of no practice. Conclusion: • Practising watching balls move and learning to move in response has strengthened the neural connections in brain areas responsible for the activity. Connection of study to question • This study demonstrates the effect of enrichment (in the form of juggling) on brain plasticity in participants who juggled • Summarize brain plasticity - Link to question: What is the effect of environmental enrichment on brain plasticity (physiological process) o The research studies outlined above demonstrates that the more a person performs a particular activity, the more neural connections are formed in the area of the brain responsible, creating a physical change in the brain. o This represents the bidirectional relationship between the environment and physiological processes occurring in the brain. •

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In conclusion neuroplasticity is the brain's ability to reorganize neural pathways (physiology) based on new experiences (environment). The interaction occurs when the enriched environments affect the neural connections in the brain by reorganising the neural connections in brain areas related to functions that are required in the enriched environment/condition. It can therefore be stated, as a result of the supporting studies and theories that a bidirectional relationship exists between the environment and physiological processes, forming a strong interaction. Plasticity describes the ability of the nervous system to adapt its structure and function in response to environmental demands, experiences, and physiological changes [6]. The human brain retains a baseline level of plasticity throughout life – this is known

as experience-dependent plasticity and underlies all learning [7]. Plasticity during sensitive periods, by contrast, is experience-expectant – an organism ‘expects’ to be exposed to a particular stimulus during this time [7]....