Navigation
Understanding the brain's remarkable ability to reorganize itself and adapt to new experiences or injuries.
If you were to lose a specific part of your brain today, could your mind 're-route' its functions to a different area tomorrow, like a GPS finding a new path around a road closure?
Neuroplasticity is the brain's ability to change its structure and function in response to experience or injury. It isn't a single process but two distinct mechanisms. Functional Plasticity is the brain's ability to move functions from a damaged area to an undamaged area. For example, after a stroke, a patient might 'relearn' to speak by using different parts of the left hemisphere. Structural Plasticity refers to the brain's ability to actually change its physical structure as a result of learning. This involves the strengthening of synapses, known as Long-Term Potentiation (LTP). If we represent the strength of a neural connection as , and the frequency of use as , we can conceptually think of the connection strengthening as over time.
Quick Check
If a person learns a new language and their brain physically develops more dense gray matter in the language centers, which type of plasticity is this?
Answer
Structural Plasticity, because it involves a physical change in the brain's anatomy.
1. Researchers compared the brains of professional violinists to non-musicians. 2. They found that the area of the somatosensory cortex representing the left hand (the fingering hand) was significantly larger in violinists. 3. This is a classic case of structural plasticity: the brain physically expanded the 'real estate' dedicated to a highly used skill.
For decades, scientists believed humans were born with all the neurons they would ever have. We now know this is false. Neurogenesis is the process by which new neurons are generated. In the adult brain, this occurs primarily in the hippocampus, the region responsible for forming new memories. Research suggests that roughly new neurons are added to the hippocampus every day. While this is a small fraction of the billions of neurons we possess, these new cells are vital for distinguishing between similar memories and maintaining cognitive flexibility. Factors like exercise and enriched environments increase the rate of neurogenesis, while chronic stress can inhibit it.
Quick Check
In which specific brain structure does most adult neurogenesis occur?
Answer
The hippocampus.
1. To become a London taxi driver, one must memorize 'The Knowledge'—25,000 streets and thousands of landmarks. 2. MRI scans showed that experienced drivers had a significantly larger posterior hippocampus compared to bus drivers who follow fixed routes. 3. This demonstrates that intensive spatial learning drives neurogenesis and structural growth in specific, relevant brain regions.
When the brain stops receiving input from a specific sense, it doesn't let that neural space go to waste. This is called cortical remapping. In individuals who are blind, the visual cortex (which usually processes sight) is often 'recruited' to process touch or sound. This is why some blind individuals develop a heightened sense of hearing or superior tactile sensitivity for reading Braille. The brain effectively 'recycles' the unused visual processing power to enhance other surviving senses. This reorganization is most dramatic in children, whose brains are more 'plastic' than adults, but it continues throughout the lifespan.
1. In extreme cases of severe epilepsy, surgeons perform a hemispherectomy, removing or disconnecting an entire half of the brain. 2. If performed on a young child, the remaining hemisphere can often take over almost all the functions of the missing half, including language and motor control. 3. This is the ultimate 'challenge' for the brain: it must compress of its required operations into of its original physical space through massive functional reorganization.
Which term describes the brain's ability to move a function (like speech) from a damaged area to a healthy one?
If the hippocampus produces approximately neurons a day, how many new neurons would be produced in a week ( days)?
True or False: In blind individuals, the visual cortex remains completely inactive and eventually dies off.
Review Tomorrow
In 24 hours, try to explain to a friend the difference between 'moving a function' and 'changing a structure' in the brain.
Practice Activity
Research the 'Phantom Limb' phenomenon and write a short paragraph on how it relates to cortical remapping in the somatosensory cortex.