Sci Adv: Sound affects early brain development

February 13, 2021 /--- To this day, scientists have not answered questions about whether or how sound affects fetal development in the womb, so mothers-to-be often wonder about the benefits of playing music during pregnancy.
now, in experiments in newborn mice, scientists at Johns Hopkins University report that sound appears to alter the pattern of "wire" in fetal brain regions.
current experiment involved newborn mice with eardules that opened 11 days after birth.
in human fetuses, the eardrings open at about 20 weeks of pregnancy.
(Photo: www.pixabay.com) The findings, published online February 12 in the journal Science Advance, could eventually help scientists find ways to detect and interfere with abnormal wiring in the brain that can cause hearing or other sensory problems.
Patrick Kanold, a professor of biomedical engineering at Johns Hopkins University and the School of Medicine, is the lead author of the paper.
during development, white matter also contains so-called subplate neurons, some of the earliest neurons to develop in the brain - humans appear at about 12 weeks of pregnancy and in mice during the second week of embryo use.
these primitive plate neurons eventually died during the development of mammals, including mice.
in humans, this occurs shortly before birth and in the first few months of life.
, however, before they died, they established a connection between the pasum and the cortical middle layer, the key channels of all perceived information in the brain.
: "The pasum is an intermediary of information from the eyes, ears and skin to the cortical layer.
neurodevelopmental problems occur when there is a problem with the pasum or its connection to the cortical layer.
" In adults, neurons in the pasum extend and extend long arm-like structures, called axons, to reach the middle layer of the cortical layer, but in fetal development, subplate neurons are located between the pasum and the cortical layer, acting as bridges.
the axons are the connections between neurons, called synapses.
in ferrets and mice, Kanold had previously mapped the circuits of subplate neurons.
Kanold has previously found that plate neurons can receive sound-related electrical signals before any other cortological neuron.
Kanold's current research, which began when he previously worked at the University of Maryland, solves two questions: What happens when sound signals reach subplate neurons, and can changes in sound signals alter the brain circuits in these areas? First, the scientists used genetically engineered mice that lacked proteins in their inner ear hair cells that converted sound into electrical impulses into the brain.
eventually translates into our perception of sound.
without these proteins, the brain would not be able to get signals.
in genetically modified mice 1 week old, the researchers found a 25 to 30 percent increase in connection between plate neurons and other cortological neurons compared to 1-week-old mice with normal hearing and normal environment.
kanold says this suggests that sound can change the brain's circuits at a very young age.
, these changes in neural connections are about a week earlier than usually seen, the researchers said.
scientists have previously believed that sensory experiences can alter cortical circuits only when neurons in the possum touch and activate the middle layer of the cortical layer, which occurs in mice about the time their eardrings open (about 11 days).
neurons are deprived of inputs such as sound, neurons reach out to look for other neurons, possibly to make up for the lack of sound," Kanold said.
this happens a week earlier than we expected, and tells us that the lack of sound is likely to reororit the immature corted connection.
"just as a lack of sound affects brain connections, scientists believe that extra sound may also affect early neuron connections in normal hearing mice."
to test this, the scientists placed the normal 2-day-old cubs in a quiet shell with or without a speaker.
scientists found that mouse cubs in quiet enclosures without beeps had stronger connections between subplates and cortical neurons than in shells with beeps.
mice, which developed between subplates and cortical neurons, also had greater diversity than mice with normal hearing raised in a quiet, silent environment.
normal hearing mice raised in quiet enclosures also had neuron connectivity similar to those of genetically engineered deaf mice in subplates and cortical areas.
, Kanold said: "In these mice, we found that differences in early sound experiences leave traces in the brain, and this exposure may be important for neurodevelopment.
" (Bioon.com) Source: Study suggestss sounds the development brain earlier than previously thought Original source: Early persy activity alters nascent subplate circuits in the auditory cortex, Science Advances (2021). DOI: 10.1126/sciadv.abc9155 , advances.sciencemag.org/lookup ... . 1126/sciadv.abc9155