The speed of brain communication

It used to be believed that the speed of information transmitted from one region of the brain to another stabilized during early adolescence. In a new study, this has been found not to be the case.

The study has been carried out by a team that includes, among others, Dorien van Blooijs and Dora Hermes, from the Mayo Clinic, in the US city of Rochester.

Because the period from late adolescence to early adulthood is prone to the onset of mental problems such as anxiety, depression, and bipolar disorders, a better understanding of brain development may help clinicians to offer treatments for these disorders.

The structural system of neural pathways in the brain or nervous system, called the human connectome, develops as people grow older. But the exact way in which structural changes affect the speed of neuronal signaling has been unknown.

“Just as the time it takes a truck to complete a journey will depend on the structure of the road, the speed of transmission of signals from one area of ​​the brain to another depends on the structure of the neural pathways,” explains Dr. Hermes. “The human connectome matures during development and aging and can be affected by disease. All of these processes can affect the speed with which information flows through the brain.” In the study, Dr. Hermes and her colleagues used pairs of electrodes with a brief electrical pulse to measure the time it takes for signals to travel from one brain region to another in 74 participants aged 4 to 51 years. Intracranial measurements were made in a small population of patients who had been implanted with electrodes to monitor epilepsy at the University Medical Center of Utrecht, in the Netherlands.

The delays in the response of the connected brain regions showed that transmission rates in the human brain increase during childhood and even into early adulthood. Around the age of 30 to 40 a stagnation occurs.

Artist’s impression of two neurons. (Image: Amazings/NCYT)

The data collected by the team indicates that transmission rates in adults were almost twice as fast compared to those normally found in children. Transmission rates were also generally faster in subjects 30 to 40 years of age than in adolescents.

The transmission speed of the brain is measured in milliseconds, a unit of time equal to one thousandth of a second. For example, the researchers determined that the neural speed of a 4-year-old patient is 45 milliseconds, that is, that is the time required for a signal to travel from the frontal region to the parietal region of the brain. In a 38-year-old patient, the same trajectory was measured in 20 milliseconds. For comparison, a blink lasts between 100 and 400 milliseconds.

The researchers are working to describe the connectivity driven by electrical stimulation in the human brain. One of the next steps is to better understand how the rate of transmission changes with the presence of neurological diseases. They are working with neurosurgeons and pediatric neurologists to find out how diseases change transmission rates from what would be considered the normal range for a certain group of people in the same age group.

The study is titled “Developmental trajectory of transmission speed in the human brain”. And it has been published in the academic journal Nature Neuroscience. (Source: Mayo Clinic)