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Exemplar: Brain development

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  • Exemplar: Brain development

The following sample is a response to the question: Discuss the role of brain development in developing as a learner. 

The sample response is an example of an exemplary response that should receive top marks.

Comments about the essay are included below.

The highlighted areas of the essay demonstrate critical thinking.

Contributed by Laura Swash

Sample essay

Essay contentMarker's comment

Brain imaging technology has allowed researchers to establish that the brain develops from ‘back to front’, with the first areas to mature being those of the hind and mid-brain related to the innate functions of grasping and sucking, movement and sight, and the last area to develop is the frontal cortex, which is associated with decision-making, planning and reflection.  There is some correlation between brain development and developing as a learner, with new neural connections being formed every day, and cognitive functions developing in parallel to these.

Introduction and focus on the question: a brief description of the development of the brain and cognitive functions.

The brain of a newborn already contains almost as many neurons as a full-grown adult brain, but connections between them are still forming, and continue to develop for the rest of a person’s life, though not at the speedy rate that they are made in childhood. Dendritic branching extends the network of synapses within the brain, while neural pruning is the process that increases its efficiency by eliminating connections that are no longer used. It is this continual maintenance and upgrading of brain function that is related to the development of cognitive functions.Knowledge and understanding shown of neural pruning and dendritic branching

Chugani (1999) reviewed cross-sectional research comparing the brain development of infants and toddlers using positron emission technology (PET) scans.  This brain imaging method determines areas of brain activity, by measuring glucose metabolism in different brain regions. In his review of studies, he found that a baby’s brain develops neuronal connections (myelinated white matter) from the back to the front, with the frontal cortex that is responsible for higher-level processing developing last.  By the age of 3 years, and until about 10 years old, the glucose metabolism, and therefore the activity and neuronal growth, is more than twice the level of that in adults. Chugani calls this a ‘window of opportunity’ for learning, and indeed it corresponds to a peak time for cognitive development, as the child learns to read, write, reason and understand ever more complex ideas.  With adolescence, glucose metabolic rates decrease to adult levels by about age 16-18 years.

Use of research to support answer: study into brain development.
Similarly, Giedd et al (2004) conducted a longitudinal MRI study into child and adolescent brain development, measuring increases and decreases in white matter (myelinated neuronal connections) and grey matter (neurons).  The longitudinal design meant that the same participants were used throughout the study, with scans conducted approximately every two years on children between 6 years and 20 years of age.  They found that brain white matter increased throughout childhood and adolescence, but grey matter development in the brain cortex showed an ‘inverted-U pattern’ of increase in earlier adolescence, and drop-off in late adolescence.  This varied between the different cortical areas. Finally, the dorsolateral prefrontal cortex, which is important for controlling impulses, does not mature until the early 20s.  This last finding has been used to try and account for the impulsive behaviour of adolescents

Use of research to support answer: study into brain development.

Clarity and organization throughout; each paragraph makes a logical connection with the one before it.
This evidence suggests a direct correlation between brain development and development as a learner and is certainly supported by Piaget’s stage theory which depends on biological readiness for transition from one developmental stage to another. These stages are the same for all humans as they are driven by biological maturation of the brain, which is a similar process for all.  Current education systems are built on this assumption, that children should be divided into age groups for learning, and that older children will be able to use more abstract reasoning than younger children.  This is why counting rods, marbles and other concrete aids are provided for young children engaged in maths but withdrawn usually after the age of twelve years, which is when they reach Piaget’s formal operational stage and become theoretically able to reason using symbols.

Knowledge and understanding shown of the implications of research into brain development.

Use of research to support answer: biological research conclusions supported by Piaget
However, other research has shown that brain development itself is subject to environmental influences, and so its effect on development as a learner is mediated environmentally. For example, Bremner (2003) found that long-term stress caused by early childhood sexual abuse was correlated with atrophy of the hippocampus and limited blood flow to the hippocampus during a memory task in adult women.  This suggests an environmental effect on both the brain and on cognition. Conversely, Maguire et al. (2000) used MRI scans to demonstrate that taxi drivers’ repeated practice and learning of routes led to increased development in the posterior hippocampus region.  Thus, learning a new skill increased the dendritic branching in the relevant area of the brain.  This is an example of cognitive development seeming to lead to brain development.   These last two examples show an interaction between environment, cognition and brain, not just a simple brain development-cognitive development correlation.Use of research to support answer: biological research conclusions critiqued by reference to two other pieces of research.

In conclusion, while brain development is correlated with cognitive development, it is not the sole determinant of it.  Brain development cannot account for individual differences in cognitive development.  Even Piaget, who believed in biological readiness for learning, allowed quite wide age margins for this learning to take place.  Moreover, later research suggested even larger margins were needed, to allow for variations in learning. Therefore, developing as a learner is a complex process requiring both brain development and a favourable environment, and itself in turn also affecting brain development.

Words: 829		Clarity and organization: the route to this conclusion has been clearly mapped, from a straightforward brain – cognition correlation to a more complex interaction between environment, cognition and brain development.