Monday, 1 July 2013

The A - Z of Sports Vision - Neurons

The normal adult brain contains around 85 billion nerve cells or neurons, each with between 1,000 and 10,000 connections to other cells, via between 100 trillion and 1,000 trillion synaptic connections. If that wasn't mind-boggling enough, consider what’s going on in the unborn foetus. In the last month of pregnancy, new neurons appear and migrate to where they are needed at the rate of 250,000 per second, resulting in almost a trillion cells at birth. These neurons are then rapidly pruned down to the 85 billion or so that we have for the rest of our life. Studies have compared the brain structures of animals raised in various environmentally normal, deprived or enriched settings. The enriched settings provided the opportunity to interact with toys, treadmills and obstacle courses. Animals placed in enriched environments had brains that were larger and contained more synaptic connections. By contrast, studies Romanian orphans (Chugani et al, 2001 for example) show significant reduced brain function as well as a smaller brain size compared with children who were adopted. As the baby explores and interacts with its environment, the neurons in its brain transmit signals to each other. To achieve the precision of the mature brain, stimulation in the form of movement and sensory experiences during the early developing years is necessary. Experience appears to exert its effects by strengthening and bonding synapses – the connections between neurons. The neural networks that are used get stronger, those that are not wither away, just as unused brain cells start dying in the first weeks after birth. Due to differences in experience, not even identical twins are wired the same. This interplay is life-long. Even the adult brain can continue to re-wire itself and make connections after exposure to new situations. The more that a particular brain network is activated the stronger the signal becomes (external stimuli send electrical impulses racing from one part of the brain to another). The brain consolidates learning by pruning away synapses and wrapping myelin around other connections to stabilise and strengthen them. At some point the signal becomes so strong and stable that these connections cannot be pruned away. Myelin is thought to be crucial in developing expert-level skills. The thicker the myelin gets, the better it insulates and the faster and more accurately the signals travel. It’s this that seems to be the key to developing a reliable golf swing or tennis serve. There’s increasing evidence that physical activity is one of the main ways the brain develops, with greater neuron and synapse production (for instance Gould et al, 1999, 2000, 2004). It seems there can be even greater rewards when decision making is involved with extensive practice (Brown et al 2003). Draganski et al (2004) used fMRI scans to examine the effect of juggling on brain development. After three months of juggling, a significant increase in grey matter (un-myelinated nerve cells) was detected in the occipital cortex and visual areas of jugglers compared with non-jugglers. If you really want to give your kids a head start in terms of hand-eye coordination, teach them to juggle. David Donner