Sunday, 2 June 2013

Neurogenesis / Network compensation


Neurogenesis is the creation of new neurons through stem cells in the human brain which occurs throughout life. This is also a new discovery and until recently most believed that neural stem cells didn't occur in adult human brains. The regulation of these stem cells occurs through molecules called growth factors.

Depression is assosciated with reduced neurogenesis. Anti-depressants boost neurogenesis by elevating levels of brain-derived neurotrophic factor (BDNF), as does exercise which is a natural anti-depressant. However, BDNF can also be increased by changing your living conditions. In experiments where mice were placed in an 'enriched' environment it was found that these same mice had notable improvements in memory tasks such as navigating through a maze. They also experienced elevated mood. The environments they were placed in consisted of larger cages, many toys and also, a running wheel. Mice which previously had learning difficulties but were then placed in this enriched environment were later found to perform just as well as mice of average ability when it came to memory tasks. The more stimulating environment also reduces the decline of memory that occurs with aging.
In another experiment, mice with a genetic predisposition for Huntingdon's disease were divided into two groups. One group was placed in the enriched environment mentioned above and the others in a normal environment (small cage, no toys, no running wheel). The mice which were placed in the enriched environment began developing symptoms much later than the other mice, indicating that environment and experience can delay the onset of this disease. Similar results were found with both Alzheimer's disease and dementia.

This part of the post is about recovering from strokes and delaying mental illnesses such as dementia and Alzheimer's disease.

In a test to deduce the effects of high and low levels of brain atrophy (shrinkage) in older individuals it was found that the regions of the brains of those individuals with high atrophy differed in activity to the brain regions activated by the low atrophy individuals when both groups were carrying out the same memory-orientated tasks. The fact that performance between both groups was relatively similar yet each group used different brain regions to perform the same task means that the brain is capable of network compensation. This means that when an area of the brain that is typically assosciated with a certain function becomes atrophied or no longer works, alternative brain regions will take on its function.

In humans, physical exercise has been shown to delay the onset of dementia and brain training (mental exercise) has been shown to reduce the effects of Alzheimer's disease.

According to Dr. Michael Valenzuela (an expert on mental decline with aging), there are three effective methods for improving brain function and slowing age-related mental decline. He calls these three methods the "Cognitive Key", "Social Key" and the "Physical Key".

The cognitive key involves learning something new, problem solving or improving memory. It is important that this key be challenging in order to produce more benefits. An example of a cognitive challenge could be learning a language or trying to remember as much of your day before going to sleep.

The social key is self-explanatory, as humans are social creatures the benefits of social interaction are numerous. Socialising promotes better cognitive functioning and elevates mood as well.

The physical key consists of some type of physical exercise or skill practice. Physical activity which is done with friends or in a group is particularly beneficial as it combines both the social and physical elements.

Some examples of beneficial activities are: travelling, learning a martial art, social shopping and also dancing. These activities are all typically done in groups and involve more than one of each key method.

Network compensation is crucial for many stroke victims who wish to recover functionality of the brain.

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