Who Shapes Our Personalities?

Posted 11/14/11 on The Doctor Weighs In

This question was, and still is, the subject of debate among philosophers, neuroscientists and psychologists. Do we have free will?

In that case it is primarily us who shape our own personality. And if neuroscientists’ contention that free will is just an illusion, then what are the factors that contribute to our personality? Not surprisingly, our mothers have a major effect on who we become in later life.

Music’s effect on the baby’s brain

What does music have to do with motherhood? I am using music as a “hook”, as an entréto studies showing the influence of pregnant mothers on the fetus.

By now it is common knowledge that babies as young as three months old react to music. In fact, studies have shown that classical music has a more profound effect on the brain than country or rock music. The reason for that lies in the more complex structure of classical music.

When fMRI studies were done on babies listening to classical music something very interesting showed up: the areas of spatial reasoning became active. Interestingly, children who listened to classical music were better at solving spatial problems, like jigsaw puzzles. And if they listened to the music over a long period of time, their spatial reasoning became even better and more long-lasting. Finally, if they actually played an instrument –they became whizzes at solving these kind of problems. The developing baby brain is recruiting neurons to lay down circuits of spatial reasoning. The connections between these neurons thicken as the music is repeated over time.

It’s not just the music, it’s the mother as well

Research has shown that babies react to music in utero as early as early as 30 weeks of pregnancy (or 28 weeks after conception). Are they reacting to the music, or are they picking up the mother’s reaction to the music?

An ingenious Japanese study provided the answer. In the study, carried out at Nagasaki University in Japan, ten pregnant volunteers were asked to watch an upbeat five-minute clip from the Julie Andrews musical, The Sound of Music. Another 14 watched a tear-jerking five minutes from the 1979 Franco Zeffirelli film The Champ, in which a boy cries at the death of his father.

The clips were ‘sandwiched’ between two extracts of neutral programs so the researchers could measure any changes in the movement of the babies. The mothers-to-be listened to the movies using earphones to guarantee their unborn babies were not being influenced by the movie’s soundtrack. Dr Kazuyuki Shinorhara, who led the study, used ultrasound scans to count the number of arm, leg and body movements of the babies while their mothers were watching the clips.

The researchers found that the fetuses moved their arms significantly more during the happy clip from The Sound of Music. In the other group, the unborn babies moved significantly less than normal while their mothers watched the tear-jerker.

This, and other experiments tells us that not only can fetuses react to music, but they can pick up on the mother’s mood.

Some more compelling evidence

As a fetus grows, it’s constantly getting messages from its mother. It’s not just hearing her heartbeat and whatever music she might play to her belly; it also gets chemical signals through the placenta.

A new study, published in Psychological Science (Nov. 2011), finds that this includes signals about the mother’s mental state. If the mother is depressed, that affects how the baby develops after it’s born.

They found something interesting: what mattered to the babies was if the environment was consistent before and after birth. That is, the babies who did best were those who either had mothers who were healthy both before and after birth, and those whose mothers were depressed before birth and stayed depressed afterward. What slowed the babies’ development was changing conditions—a mother who went from depressed before birth to healthy after or healthy before birth to depressed after.

In the long term, having a depressed mother could lead to neurological problems and psychiatric disorders. In another study, Sandman and his team found that older children whose mothers were anxious during pregnancy, which often is co-morbid with depression, have differences in certain brain structures.

Past studies have shown that stressed mothers-to-be are at higher risk of stillbirth and premature birth. Babies born to stressed mothers are twice as likely to have lower-than-average IQs. They are also more likely to be hyperactive, suffer from emotional problems and refuse to do as they are told.

What did we learn?

The evidence that the mother’s mood affects the fetus’ brain development is inescapable. It is only at week 11 of pregnancy that the embryo is defined as a fetus. It is at this stage that rudiments of response to outside influences, such as the mother’s hormones, become evident; genitalia are forming, and the brain begins its process of organizing. Any lesson here as to when a fetus can be viewed as a person?’

A much more important lesson: it is rarely that obstetricians pay much attention to the mental health of the pregnant mother. Attention to this
aspect can prevent major problems later in life. Is it conceivable that the latest “epidemic” of cognitively underperforming and hyperactive children is related to the increased stress of pregnant mothers in today’s society?

Dov Michaeli MD PhD is a basic researcher who writes on the life sciences at The Doctor Weighs In.