the school age child
Key Brain Facts - a personal view by Buffy McClelland
| the brain | the senses | brain development | movement&learning |
What do the main bits of our brains do? A simple model of the brain suggests that we have three main regions in our brains, the Cerebral Cortex at the top (pale green), the Limbic System in the middle (white) and the Central Core at the bottom and back (purple).
The Cerebral Cortex coordinates the brain's higher cognitive and emotional functions. It has two symmetrical halves (left and right cerebral hemispheres). The back part of the Cerebral Cortex is separated into three lobes which process incoming sensory input, generally being vision, hearing and tactile/proprioceptive sensations. The front part of the Cerebral Cortex is called the Prefrontal Cortex (also called the Frontal Cortex), and this is where all of our sensory information is pulled together to allow us to make decisions about how to respond to any change in our environment. The left and right cerebral brain hemispheres are connected by a thick mass of nerve fibres called the Corpus Callosum.
The Limbic System is a catch-all name for a number of very disparate mid-brain regions: the Hippocampus is important in memory, emotion and learning; the Amydgala resonds to perceived threats, and also contributes to drives such as hunger, thirst and sex; the Hypothalamus helps regulate our blood, body temperature and hormones.
The Central Core provides the first stages of sensory information processing, and helps to regulate basic life processes including breathing, heart rate etc. The three most important areas for us to consider are the Reticular Formation which signals the cerebral cortex to attend to new stimulation and to remain alert even during sleep; The Thalamus assesses sensory input and decides whether it relates to safe or unsafe circumstances (for example), and then sends the sensory input onwards to the appropriate area of the cerebral cortex; and the Cerebellum (the rear lobe in purple) which coordinates body movements, controls posture, and maintains balance.
How do our senses work? Our senses take several different routes into the brain. Sight goes direct to the visual cortex from the eyes via the optic nerve (pathway shown in red in the picture), and also into the cerebellum. Hearing passes into the auditory cortex and the cerebellum via the blue pathway in the picture. Our sense of touch and proprioception enters the brain via the brainstem via the green pathway. Our frontal cortex (hidden on the other side of this picture) makes sense of all this sensory information and decides how we should respond to our experiences. Physical action is generated in the motor cortex and our muscles move in response to signals sent out down the spinal cord via the yellow pathway.
What controls brain development? The main answer is our experience through our senses. Scientists used to think that how our brain developed was mostly controlled by our genetics. Modern science now tells us that our brains mostly wire up after birth, growing connections between the brain cells we are born with, in response to our experience of the world around us. Genetics obviously has an impact, just not as much as was previously thought. The growing baby experiences the world through her senses - sight, touch, hearing, smell and taste - and this experience shapes her brain development.
This means that our brains are programmed to change in response to doing something different or even thinking in a different way, by actually growing new connections between brain cells, and this process continues throughout our entire live. Scientist are now using this possibility to help the brain rewire after strokes, so that completely different regions can take over the control functions which were lost by damage to particular brain regions. Conversely, if we don't use a particular brain pathway for a long time, the brain dismantles those connections for use elsewhere. "Use it, or lose it" is true, after all!
There are "critical periods" during which the brain is primed and ready to blossom. For example, great steps forward in language are usually made between the ages of one and three. However, our brains are always able to change in response to new experiences, and the older child and adult brain can and does enthusiastically respond and change through new stimuli experienced through the senses. Helping the brain see the world more effectively through the senses allows more accurate information processing, generally improving many aspects of life, at all ages from infancy to old age.
Movement and Learning. Neuroscientists now know that the brain learns and changes through movement. Exercise promotes the growth of new neurons in the adult human brain, and not just in the areas of the brain which are used to control movement. The hippocampus (which is important in memory, emotion and learning) is particularly susceptible to grow new brain cells in response to movement. Fabel and Kempermann (2008) suggest that growth of new neurons in the adult brain is beneficial in situations where we need to respond to something new by learning something new, so the new experience (experienced through the senses) actually causes the brain to re-wire for more efficient learning. These authors argue that the human brain is programmed to grow new neurons in response to movement because of our ancestry; the link between locomotion and cognition goes back to our evolutionary animal roots.
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Fabel K, Kempermann G. Physical activity and the regulation of neurogenesis in the adult and aging brain. Neuromolecular Med 2008;10:59–66.
Text and Layout, Copyright © Dr Buffy McClelland, 2010. All rights reserved.
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