Tuesday, August 4, 2009

Neither our Brain nor our Character is Cast in Stone

The popular view until a few decades ago was that the brain comes with a fixed number of cells (neurons) and their interconnections get unchangeably defined by age five deciding what we are for the rest of our life.

It was also a common notion that our character, defined by the genes which we inherit from our parents, remains unalterable.

As Dr. P. Nathanielsz observed a few years ago, the influence of genes is one hundred percent only at the time conception takes place. From the very next moment the environment we are exposed to play a tremendous role in going to determine our mental and physical health, behavior, attitude and character -- the environment may be the womb of our mother when we were still a fetus or the outside world after we are born.

So ‘what we are’ is not rigidly fixed for life when we are given birth to!

Undoubtedly the genes hold the basic blueprint of our life. But the genes have to get switched on and off at appropriate times so that their effect shows up on you. A study of the environmental influence that can trigger the turning on/off of the genes is called “Epigenetics.” From such studies scientists are now able to understand the processes by which a change takes place in the basic blueprint of our life.

Brain is considered now to be highly “plastic” i.e. changeable - new neurons generate, which neurons are connected and which are disconnected keeps constantly changing; the connecting wires (axons) may vary in their communicative strength (insulation) etc. Further, there are another type of cells in the brain, ten times that of neurons. These are called glia. Changes in the glial cells too take place and their role in defining what we are is just being explored.

Here are three latest interesting reports that reinforce these findings:

1. The atmosphere we live in, the pollutants we are exposed to and life style we lead do affect the switching on/off of our genes.
: http://www.scientificamerican.com/article.cfm?id=silencing-genes-chemical-contaminants-cancer-diabetes

“Each of us starts life with a particular set of genes, 20,000 to 25,000 of them (or less according to some other estimates). Now scientists are amassing a growing body of evidence that pollutants and chemicals might be altering those genes—not by mutating them, but by sending subtle signals that silence them or switch them on at the wrong times.…new findings suggest chemicals in our environment and in our food can alter genes, leaving people vulnerable to a variety of diseases and disorders, including diabetes, asthma, cancer and obesity.”

Dr. Linda S. Birnbaum says: Exposure to gene-altering substances, particularly in the womb and shortly after birth, “can lead to increased susceptibility to disease. ….. The susceptibility persists long after the exposure is gone, even decades later. Glands, organs, and systems can be permanently altered. ….. There is a huge potential impact from these exposures, partly because the changes may be inherited across generations. You may be affected by what your mother and grandmother were exposed to during pregnancy,”

We need not take this work as an “Environmentalist rabble rouser.” Nor do we have to panic over it. What for the present we can conclude is that even such trace amounts of certain chemicals have a tremendous influence in determining not only what we are but also what our own progeny is going to be.

2. Our brain acts as if we are actually doing a thing when we read about something being done:
: http://www.scientificamerican.com/podcast/episode.cfm?id=brains-moving-experience-when-readi-09-07-30&sc=WR_20090804

Over a decade ago it was discovered that the neurons responsible for motion in our brain work in the same way whether we do those actions by ourselves or when we see others doing those actions. It was also the case with emotions. The neurons which reflect in us the actions and emotions of others were named “mirror neurons.” The present study shows that “reading about something turns on the same brain regions that control doing that thing” in our brain.

3. Our brain can be trained to alter the way it works even at a late age:
: http://www.scientificamerican.com/article.cfm?id=seeing-in-3-d&page=2

Dr. Sue Barry was cross-eyed and she was seeing the world only flat – in two dimensions. Surgery in childhood corrected the cross eyes but could not give her 3-D vision of the world. She lacked the ability to gauze depth i.e. stereoscopic vision which many of us just take it for granted.

At her age 48, she could retrain her brain to see stereoscopically. Her experience of a 3-D world was a revelation to her. Saying it in her words: “When I began to see in stereo, it came as an enormous surprise and a great gift. For the first time, I could see the volumes of space between different tree branches, and I liked immersing myself in those inviting pockets of space. As I walk about, leaves, pine needles, and flowers, - even light fixtures and ceiling pipes - seem to float on a medium more substantial than air. Snow no longer appears to fall in one plane slightly in front of me. Now, the snowflakes envelope me, floating by in layers and layers of depth. …. ordinary views like these still fill me with a deep sense of wonder and joy.”

Dr. S. Barry, herself a neuroscientist, adds this: "We can change the synapses and wiring in our brain and thus learn new things if we are exposed to and pay attention to novel situations, if we stay motivated, and if we practice. Novel experiences, as well as the anticipation of a reward, stimulate ancient areas of our brain, such as the brainstem and basal forebrain. Activation of these areas liberate powerful neuromodulators, including dopamine and serotonin, onto our cortical neurons and circuits, and these neuromodulators facilitate and strengthen synaptic changes which underlie learning. Practice and repetition are necessary to make these changes long-lasting."

Added on 23 Sep 2011:

4.  Brain continues to develop well into our 20s:
: http://medicalxpress.com/news/2011-09-brain-20s.html

"The research results revealed that young adult brains were continuing to develop wiring to the frontal lobe; tracts responsible for complex cognitive tasks such as inhibition, high-level functioning and attention. The researchers speculated in their article that this may be due to a plethora of life experiences in young adulthood such as pursing post-secondary education, starting a career, independence and developing new social and family relationships. An important observation the researchers made when reviewing the brain-imaging scan results was that in some people, several tracts showed reductions in white matter integrity over time, which is associated with the brain degrading."

5.  Viruses affect genes which in turn influence behavior:

Death-seeking caterpillar zombies: "Though pathogens controlling host behavior is not a new story, the genetic basis for these behavior changes remains a mystery. Researchers now have identified a gene, called egt, which allows the baculovirus to take the joystick and manipulate the caterpillars' climbing behavior. Healthy caterpillars remained below while the infected ones climbed and clung to the top of the container until they died, the researchers describe in Science. When the scientists deleted the egt gene, this behavior ceased, while reinserting the gene restored the climbing compulsion. This provides the first lead offering a genetic explanation on how some viruses are able to control their host's behavior."

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