Posts tagged birth
Posts tagged birth
Neurons that process sensory information such as touch and vision are arranged in precise, well-characterized maps that are crucial for translating perception into understanding. A study published by Cell Press on October 14 in the journal Developmental Cell reveals that the actual act of birth in mice causes a reduction in a brain chemical called serotonin in the newborn mice, triggering sensory maps to form. The findings shed light on the key role of a dramatic environmental event in the development of neural circuits and reveal that birth itself is one of the triggers that prepares the newborn for survival outside the womb.
"Our results clearly demonstrate that birth has active roles in brain formation and maturation," says senior study author Hiroshi Kawasaki of Kanazawa University in Japan. "We found that birth regulates neuronal circuit formation not only in the somatosensory system but also in the visual system. Therefore, it seems reasonable to speculate that birth actually plays a wider role in various brain regions."
Mammals ranging from mice to humans have brain maps that represent various types of sensory information. In a region of the rodent brain known as the barrel cortex, neurons that process tactile information from whiskers are arranged in a map corresponding to the spatial pattern of whiskers on the snout, with neighboring columns of neurons responding to stimulation of adjacent whiskers. Although previous studies have shown that the neurotransmitter serotonin influences the development of sensory maps, its specific role during normal development has not been clear until now.
In this new study, Kawasaki and his team find that the birth of mouse pups leads to a drop in serotonin levels in the newborn’s brain, triggering the formation of neural circuits in the barrel cortex and in the lateral geniculate nucleus (LGN), a brain region that processes visual information. When mice were treated with drugs that either induced preterm birth or decreased serotonin signaling, neural circuits in the barrel cortex as well as in the LGN formed more quickly. Conversely, neural circuits in the barrel cortex failed to form when the mice were treated with a drug that increased serotonin signaling, suggesting that a reduction in levels of this neurotransmitter is crucial for sensory map formation.
Because serotonin also plays a key role in mental disorders, it is possible that abnormalities in birth processes and the effects on subsequent serotonin signaling and brain development could increase the risk of psychiatric diseases. “Uncovering the entire picture of the downstream signaling pathways of birth may lead to the development of new therapeutic methods to control the risk of psychiatric diseases induced by abnormal birth,” Kawasaki says.
Vaginal birth triggers the expression of a protein in the brains of newborns that improves brain development and function in adulthood, according to a new study by Yale School of Medicine researchers, who also found that this protein expression is impaired in the brains of offspring delivered by caesarean section (C-sections).
These findings are published in the August issue of PLoS ONE by a team of researchers led by Tamas Horvath, the Jean and David W. Wallace Professor of Biomedical Research and chair of the Department of Comparative Medicine at Yale School of Medicine.
The team studied the effect of natural and surgical deliveries on mitochondrial uncoupling protein 2 (UCP2) in mice. UCP2 is important for the proper development of hippocampal neurons and circuits. This area of the brain is responsible for short- and long-term memory. UCP2 is involved in cellular metabolism of fat, which is a key component of breast milk, suggesting that induction of UCP2 by natural birth may aid the transition to breast feeding.
The researchers found that natural birth triggered UCP2 expression in the neurons located in the hippocampal region of the brain. This was diminished in the brains of mice born via C-section. Knocking out the UCP2 gene or chemically inhibiting UCP2 function interfered with the differentiation of hippocampal neurons and circuits, and impaired adult behaviors related to hippocampal functions.
“These results reveal a potentially critical role of UCP2 in the proper development of brain circuits and related behaviors,” said Horvath. “The increasing prevalence of C-sections driven by convenience rather than medical necessity may have a previously unsuspected lasting effect on brain development and function in humans as well.”
Mother gave birth in a specially-designed ‘open’ MRI scanner. The footage shows that each time the uterus contracts it exerts pressure on the baby sliding him further down the birth canal. When the contraction is over the uterus relaxes and the baby’s head recedes slightly.