Can humans develop new brain cells, as adults? Scientists do not generally agree about this, as it is a relatively new field of investigation. However, Dr Sandrine Thuret, a neuroscientist with expertise in cellular, molecular, ageing and behavioral biology, says you can. In her laboratory at King’s College London, Dr. Thuret studies adult neurogenesis – the process of forming new brain cells in specific brain regions in adults.
Thuret’s work concentrates on the hippocampus, which is a gray structure within the middle of the brain. Scientists have long known that the hippocampus is essential for learning, emotion, mood and memory. Recently, researchers learned that the hippocampus is a unique structure within the mammalian brain which is capable of generating new neurons or brain cells.A researcher, Jonas Frisen of the Karolinska Institute, found that the human brain generates approximately seven hundred new neurons each day within the hippocampus. Dr Thuret notes:
“While this may not appear to be much when compared to the several billions of neurons within the human brain, by the time you clock age fifty, you would have exchanged all the neurons you were born with within the brain with adult generated neurons.”
The Importance Of Adult Neurogenesis
As stated earlier, new neurons produced within the hippocampus are essential for memory and learning. “And within the laboratory,” states Dr Thuret, “we have found that if the adult’s brain capability to generate new neurons within the hippocampus is blocked, then certain memory abilities are also blocked”. Furthermore, according to the scientist, this is particularly new and true for spatial recognition.
Spatial recognition is utilized in everyday activities, including simple tasks such as deciding what size of container is required to hold a particular object or navigating your way within the city. It is also utilized when you look within a mirror and understand which side of the reflection correlates with the left side and which with the right. Also, spatial recognition skills help to keep individuals from getting lost when adjusting to a new apartment or office building.
“A lot are still being discovered”, says Thuret, “and aside from being essential for memory capacity, neurons are also essential for the quality or features of the memory”. Also, they are beneficial for adding time to your memory as well as helping to differentiate memories that are very similar. For example how are you able to locate your bike, which you park every day at the station, within the same area; however in a somewhat different position?
Neurogenesis And Depression
Thuret also says that she and her colleagues at King’s College London have been conducting some research on neurogenesis and depression. “In studies of depression using animal models, we have discovered that there is a lower level of generation of new neurons in the brain”, says the scientist. “And if antidepressants are given, it was discovered that the synthesis of these new neurons increased, and depression symptoms were decreased, thereby establishing a clear connection between depression and neurogenesis.” However, if you merely block the generation of new brain cells, then the antidepressant’s efficacy will be blocked as well.
This finding helps to explain why some patients who have been informed that their cancer is cured still develop depression symptoms. According to Thuret, the medication which doctors give to their patients which stops the multiplication of the cancer cells also impedes or stops the generation of new neurons in the patients’ brains. In addition, it will take some time to produce new neurons that attain normal functions.
“Thus, collectively, now we believe that there is sufficient evidence to assert that neurogenesis is an excellent choice if we wish to enhance mood or memory formation, or even stop the decline connected to stress or connected to ageing” – observed Dr. Thuret.
Can Neurogenesis Be Controlled?
Thuret says the answer to this question is a definite yes, and she details some activities and behaviors that can influence the generation of new neurons within the adult brain. These activities include:
- Learning : This will increase the generation of new neurons.
- Stress: Stress will reduce the generation of new neurons within the hippocampus.
- Sleep deprivation: This will also reduce neurogenesis.
- Sex: Sex will boost the generation of new neurons within the hippocampus of the adult brain; however Thuret cautions that balance is important. Excessive sex can actually lead to sleep deprivation and attendant medical disorders.
- Ageing: Generation of new neurons will reduce as you age, however that does not mean it will stop completely.
- Running: Running can greatly increase the generation of new neurons within the hippocampus of the adult brain. Thuret offers more explanation about this.
Thuret points to an experiment conducted by Salt Institute’s Rusty Gage, which showed that the environment can influence the generation of new neurons within the brain. In the study, some mice were placed in a cage with a running wheel, while others were placed in another cage with no running wheel.
At the end of the experiment, mice from the cage with a running wheel showed a huge increase in the generation of new neurons within the hippocampus, whilst mice from the cage with no running wheel showed very little increase in the generation of new neurons within the hippocampus of the brain. This shows that activity has a huge impact on neurogenesis.
The neuroscientist also points out that diet can also impact the generation of new neurons within the hippocampus, and also specifies some eating practices that can influence neurogenesis. These practices include:
- Calorie restriction of about twenty to thirty percent will boost generation of new neurons.
- Intermittent fasting (abstaining from calories for a brief time period) will boost neurogenesis.
- Consumption of flavonoids that are contained within blueberries or dark chocolate will boost neurogenesis.
- Omega 3 fatty acids which are contained in fatty fish such as salmon will boost the generation of new neurons within the hippocampus.
- High saturated fat diet will negatively impact neurogenesis.
- Consumption of alcohol will reduce the generation of new neurons in the brain. Nevertheless, everything is not lost. Dr. Thuret points out that resveratrol, which is a component of red wine, has been found to boost the survival of newborn neurons. Thus, when next you are at a get-together, you may want to opt for this potentially “neurogenesis-neutral” drink.
- A soft diet (diet that avoids or restricts foods which are difficult to chew or swallow) impairs neurogenesis.
“Even though all of this data has been generated utilising animal models, this diet has been given to human participants as well”, says Dr Sandrine Thuret, “and what we discovered is that the diet moderates mood and memory in the same way as it moderates the generation of new neurons within the hippocampus”.
For example calorie restriction will enhance memory capacity, while a diet high in fat will aggravate depression symptoms. This is in contrast to omega III fatty acids, which boosts the generation of new neurons within the hippocampus, and also aid to reduce depression symptoms.
“Thus we believe that the influence of diet on mood, memory and mental health, is actually regulated by the generation of the new neurons within the hippocampus”, concludes Thuret. “And it is not just what you consume, but the food texture, when you consume the food and the quantity of the food you consume.
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