Meaning

"Earl Miller, an expert at the Massachusetts Institute of Technology, studied the prefrontal cortex, which controls the brain while a person is multitasking.According to his studies, the size of this cortex varies between species, He found that for humans, the size of this part constitutes one third of the brain, while it is only 4 to 5 percent in dogs, and about 15% in monkeys. Given that this cortex is larger on a human, it allows a human to be more flexible and accurate in his or her multitasking.. However, Miller wanted to look further into whether the cortex was truly processing information about two different tasks simultaneously. He designed an experiment where he presents visual stimulants to his subjects in a wax that mimics multi-tasking. Miller then attached sensors to the patients " heads to pick up the electric patterns of the brain. This sensor would show if " the brain particles, called neurons, were truly processing two different tasks. What he found is that the brain neurons only lit up in singular areas one at a time, and never simultaneously."

I read this article in a scientific report and I can't understand the meaning of the red sentence. Can anyone explain?

Faithfully,

Nguyen