Window in the skull: scientists investigated the human brain with ultrasound during a video game

For the first time, scientists used ultrasound waves to look into the brain of a living person. The man’s brain activity was recorded while he was performing tasks outside a medical facility, including playing a video game.

To achieve this, the researchers implanted a material in the man’s skull that allows ultrasound waves to pass into the brain. After passing through this «acoustically transparent» window, the waves bounced off the boundaries between tissues and returned to an ultrasound transducer connected to a scanner. The data obtained allowed scientists to create a picture of what is happening in the brain — similar to how an ultrasound scan visualizes a fetus in the womb.

The team from the California Institute of Technology and the University of Southern California observed changes in blood volume in the brain over time, zooming in on the posterior parietal cortex and motor cortex, which are related to movement coordination. Assessing changes in blood volume is one way to indirectly track the activity of brain cells. When neurons are active, they need more oxygen and nutrients delivered by blood vessels.

The new study builds on previous research in primates. Working with humans, the scientists were able to use ultrasound imaging to accurately record neural activity during a video game and guitar playing. The team published the study in the journal Science Translational Medicine.

Functional ultrasound imaging (ultrasound that monitors changes in blood volume in the brain) is considered a promising alternative to conventional brain imaging methods such as MRI. This method is more sensitive to changes in brain activity, and the resulting images have a higher resolution. The method also does not require patients to lie still for a long time.

Thus, it is possible to track the brain activity of patients in real conditions. Currently, this is also possible with electroencephalography, but EEG tracks electrical activity through the scalp and skull, so it is not very accurate.

The human skull has also always been a barrier to ultrasound waves. In the study, scientists overcame this obstacle by removing part of the skull. This was done for therapeutic purposes to reduce the pressure in the patient’s brain after a severe traumatic brain injury. Usually, patients in such cases are fitted with a titanium mesh or a custom-made implant. In this case, the team created an acoustically transparent implant. In the future, the new technique may not be limited to patients with TBI, the study authors say.

Source: LiveScience