Experts believe that there may be a link between brain development and sounds. Recent studies have proven their theory to be true.
The newest study that scientists made suggests that sound may actually have an impact on the development of the fetus, even before the ear canals open and fully develop. The researchers conducted a study on deaf newborn mice and noticed that the animals had a different brain pattern than regular hearing. Changes took place a week earlier than they expected, and this was based on their knowledge on brain development.
The study required exposure to sound. The experts behind the study noticed more diverse cortical connections in the deaf mice. The other set of deaf mice, on the other hand, were placed on silent enclosures, and this showed that the brain connections didn’t change. If this research would be indicative of anything, this would be in finding new ways to identify and treat hearing disorders and sensory issues very early in life.
Expectant mothers out there often wonder whether or not they should introduce music to the fetus in their wombs. It is for this very reason that scientists that about conducting an experiment to reveal the intricacies of the brain and how the different parts process new sensory information.
Hence, the researchers behind the study set out to observe the impact of sound signals on subplate neurons. The said neurons are actually one of the first aspects to develop in the brain. These same neurons are also the first to die off either before birth or soon after. Moreover, they also wanted to see if they changed the sound signals, would the brain circuits change earlier as well.
Dr, Patrick Kanold, the senior study author and professor of biomedical engineering at John Hopkins University, said, “As scientists, we are looking for answers to basic questions about how we become who we are. Specifically, I am looking at how our sensory environment shapes us and how early in fetal development this starts happening.”
If the studies stay on track as expected, the future looks bright in this field. The findings will make it easier to track, assess, and potentially correct irregular brain activity and patterns that are associated with congenital sensory conditions in humans.
The study, which involves researchers from Johns Hopkins, in Baltimore, MD, and the University of Maryland, in College Park, appears in the recent article of Science Advances.
The connection between sound exposure and fetal development
Some research findings suggest that a fetus may actually begin to hear noises such as bodily sounds at around 18 weeks into their development. Then, the hearing should be fully developed between 26 to 29 weeks. After which, the baby inside the womb may actually react to outside noises. They reaction can be gauged on movement and pulse. The researchers noticed the increase in both from expectant mothers. In fact, they may also cry or become startled when they hear loud noises.
After the 32 weeks of gestation period, these developing babies may even begin to recognize vowel sounds and music. They may be partial to music that mimics the human heartbeat, which is around 60 beats per minute. As they believe, this can actually also be the most beneficial.
More research needed
At this point in time, researchers are still unsure when a fetus develops the ability to fully process sensory information. They want to delve deeper into how exposure to sound influences development. So, the uncertainty makes it hard to diagnose and treat congenital sensory disorders. Along with the uncertainly also comes frustration when it comes to searching for more ways to nurture these babies.
Researchers haven’t given up hope, though. They’ve been continually trying to figure out how exposure to sounds such as music or speaking helps fetal development. They’ve been doing this over the years and are looking into new research method.
There have been several researches conducted on the same subject matter. Some of these studies show that early exposure to music may help in the development of early socioemotional development and sound perception. It’s also been suggested in some studies that prenatal exposure to music and noise encourage the thickness and growth rate of cells in certain parts of the brain, especially those that process sensory information. Other studies also support the idea that developing babies may be able to recognize voices that they often hear.
As for the newest research that involved newborn mice, findings suggest that fetal development may be affected by sound earlier than previously thought. Further findings also hint at how fetal sound exposure may also help the number, diversity, and strength of extremely early neural connections. Hence, the men and women behind the study believe that neurodevelopment may change for the better. Says Dr. Kanold, “In these mice, we see that the difference in early sound experience leaves a trace in the brain, and this exposure to sound may be important for neurodevelopment.”
The connection between sound exposure and brain development
The team’s new research looks into the impact of sound exposure on subplate neurons in the cortex. This is the white portion of the brain that’s in charge of processing sensory information, one of its many vital functions. The said subplate neurons are among the first cells to develop. These cells also die off from before birth and a few months after that. But before they die off, they create bridges that connect sensory information between the thalamus and middle cortex. The former is the region of the brain that transmits sensory signals to the cortex set to be interpreted.
Before working with mice, the team worked with ferrets. Dr. Kanold and his team discovered that subplate neurons are the first type of cortical neuron that has the ability to take in sound signals.
The research was divided into parts. The first part allowd the researchers to discover that genetically engineered week-old deaf mice had more subplate and other cortical neural connections than mice that don’t suffer from hearing loss and that had been raised regularly. Earlier, they simply assumed that sensory signals could only change cortical connections after neurons from the thalamus had reached out to bridge with the cortex, which is when ear canal subsequently opens.
“When neurons are deprived of input, such as sound, the neurons reach out to find other neurons, possibly to compensate for the lack of sound,” Dr. Kanold further expresses. He continues, “This is happening a week earlier than we thought it would and tells us that the lack of sound likely reorganizes connections in the immature cortex.”
The second part of the study required the team to test whether additional sound exposure would impact the early neural development. In order to pull this off, they kept 2-day-old mice with regular hearing in a quiet space. The other set of mice were in an enclosure equipped with a small speaker that made a beeping sound.
The young mice kept in the enclosure with the beeping showed stronger connections between subplate and cortical neurons. However, the researchers also noticed that difference was less significant than that between the deaf mice and those with regular hearing.
All in all, the mouse pups exposed to the beeps developed greater diversity in the type of subplate-cortical. The mice with regular hearing who were kept in a quiet area also had similar subplate-cortical connections to the experimental group.
In order to further confirm the studies and form more solid conclusions, the researchers need to replicate the environment on a larger scale involving humans. This will be reserved for the future where the team will assess how sound shapes brain development. Their end goal is to identify the role and significance of fetal sound exposure in development. More specifically, they aspire to look more into brain pattern changes related to congenital deafness. This will, in their hope, help fit cochlear implants in infants. Moreover, another goal of theirs is to develop biomarkers that help point out and identify problems that are connected to subplate neuron connection abnormalities. Infants born prematurely are also considered for the future.
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