A team of neuroscientists and neurosurgeons at the University of California have figured out how brain tumors affect human cognition. Study published magazine Nature.
Scientists have long known that brain tumors, particularly glioblastomas (the most common and most aggressive form of brain tumor), interfere with the normal functioning of the brain. However, what exactly causes cognitive decline in patients is still unknown.
“Cancer cells produce substances that can act as neurotransmitters, proteins that help neurons communicate with each other. These excess neurotransmitters cause neurons to become hyperactive and release chemicals that stimulate and accelerate the growth of cancer cells.
Scientists have wondered how this feedback loop affects the behavior and cognition of people with brain cancer. To examine how glioblastomas interact with neural circuits in the human brain, the authors recorded the brain activity of patients with gliomas during brain surgery to remove a tumor. Pictures of ordinary objects or animals were shown and asked to name what they were depicting.
“The language networks in their brains were activated as expected. However, we found that regions of the brain infested with tumors were also activated during these tasks when they should not have been. This surprising finding shows that tumors can hijack and reconfigure connections in surrounding brain tissue and increase their activity. But although they were hyperactive, they were not strong enough,” the scientists explained.
This may explain the cognitive decline often associated with glioma progression. The brain cells involved in the tumor were so damaged that they needed to recruit additional cells in other areas to complete the tasks, the researchers said.