plasticity

• Plasticity refers to the brain’s tendency to change and adapt as a result of experience and new learning. During infancy the brain experiences rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 at age 2-3 years which is twice as many as there are in the adult brain. As we age, rarely used connections are deleted and frequently used connections are strengthened in a process known as ‘synaptic pruning’.
• It is suggested that existing neural connections can change, or new connections formed, at any point in life as a result of learning and experience (plasticity). Functional recovery is a form of plasticity following damage through trauma in which the brain is able to re-distribute or transfer functions usually performed by the damaged area to other undamaged areas. It is proposed that secondary

  neural pathways that would not typically be used to carry out a task are activated to enable functioning to continue.
• Functional recovery can also involve axonal sprouting, in which new nerve endings connect with

  other undamaged nerve cells to form new neuronal pathways, and the recruitment of similar areas on the

  opposite side of the brain to perform tasks.
• There is research evidence to support neural plasticity. Maguire et al (2000) studied the brains of London taxi drivers and found significantly more grey matter in the posterior hippocampus than in a matched control group. As this part of the brain is associated with the development of spatial and navigational skills, this therefore suggests that the learning necessary to become a London taxi driver has led to changes in the drivers’ brains, therefore supporting the proposal of plasticity.
• Furthermore, the understanding of the processes involved in plasticity as contributed to therapies in the form of neurorehabilitation. Recovery of function can be rapid initially but then slow down so physical therapy may be required to maintain improvements in functioning. This may include movement therapy and electrical stimulation of the brain to counter the deficits in motor and/or cognitive functioning. This therefore indicates that while the brain can fix itself to a certain extent, an understanding of the processes involved can lead to interventions that can maintain or build upon such improvements.
• However, while plasticity can bring benefits in the form of functional recovery, it can also have negative consequences. For example, 60-80% of amputees have been known to develop phantom limb syndrome where they continue to experience sensations in the missing limb as if it were still there. Such sensations are often unpleasant and painful and it is thought that these sensations are due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss. While plasticity can often bring benefits for patients following trauma, it is important to note that it can also lead to negative consequences.