2.4 Neuroplasticity

As the brain sends and receives signals, it changes itself. The neural pathways continually change with experience. New connections are made, damaged ones are repaired, unused ones are pruned. This ability of the brain to change its structure and function through its experiences is called neuroplasticity. Neuroplasticity is the basis for learning and memory, for making changes in our behavior as a result of experience or as a result of damage or injury. Experience changes the brain by creating new connections, primarily by increasing the new synapses on dendrites. In Chapter 5 we will learn about specific changes chemical and structural that occur at the cellular level and within a simple neural circuit. Recent studies have suggested that the brain can produce new cells, a process called neurogenesis (vanPragg, Kempermann, & Gage, 1999). In her Ted talk, Thuret (2015) suggests that we can enhance neurogenesis by continuing to learn and maintaining a diet containing omega-3 fatty acids and flavanoids, whereas stress and sleep deprivation can inhibit such growth.

Our brain is remarkably adaptive and changes throughout our lives. The progression of typical changes related to maturation is described in more detail in Chapter 3. These changes are similar across individuals. Such changes can occur between distant connections. The changes related to experience are unique to each individual’s experiences; and are most likely to occur in local circuits. These experience-related changes are prolific in childhood and adolescence. However, they do not stop at puberty. Neuroplasticity continues throughout life (Kolb  et al., 2016). Neural circuits change as we practice physical activities, such as playing soccer or playing an instrument, and cognitive events, such as learning to read or studying physics. Studies have documented that enriched environments contribute to brain growth. Sirevaag and Greenough (1988) compared the brains of rats raised in complex environments to those of rats raised in standard, simple cages. The brains of rats raised in the complex environments were more developed. They had greater numbers of synapses, longer dendrites and showed more growth in glial processes and vascular volume.

The brain’s plasticity comes into to play when a person suffers brain damage. Brain plasticity has also been observed when a person has damage to a body part that leads to changes in the way that the sensory motor areas of the brain are organized. For example, Ramachandran (1993) found that individuals with an amputated hand showed a map of sensitivity on their cheek that was explained as cortical reorganization of the somatosensory cortex. A less dramatic example of brain plasticity and injury is to consider what happens in concussions. Nerve fibers can be broken. It takes time for them to regrow. In severe cases, they may be permanently damaged.