A team of neuroscientists and neurosurgeons at a leading research medical center in California has clarified how brain tumors influence thinking and memory. The findings come from modern investigations into the neural basis of cognition and are reported in a prominent scientific publication.
It is well established that brain tumors, with glioblastomas being the most common and the most aggressive type, disrupt normal brain function. Yet the precise mechanisms by which these tumors contribute to cognitive decline remain a subject of ongoing study and debate among clinicians and researchers.
Researchers explain that cancer cells can produce substances that resemble natural brain neurotransmitters, the chemical messengers neurons rely on to communicate. When these tumor-derived signals accumulate, they can push nearby neurons into heightened activity. This hyperactivity may feed a cycle that not only alters local circuits but also influences the wider neural networks that support thought, language, and executive function.
To explore how gliomas interact with human brain circuitry, scientists monitored brain activity in patients undergoing surgical removal of tumors. During awake procedures, participants were exposed to images of common objects or familiar animals and asked to identify them. The setup allowed direct observation of how the brain processes recognition tasks in real time, in the presence of malignant tissue.
Remarkably, language networks in the eloquent cortex behaved as expected for task performance, yet regions newly invaded by tumor cells also showed activation patterns during these tasks when activation would ordinarily be absent. This unexpected activity suggests that tumors can commandeer and rewire connections in surrounding healthy tissue, amplifying neural signals in ways that may not help perception but still reflect active engagement with the task. Importantly, this reconfiguration did not result in robust functional output that could compensate for the damage caused by the tumor, indicating a delicate and imperfect attempt by the brain to adapt.
Overall, the study provides a potential explanation for why cognitive abilities often deteriorate as gliomas advance. The cancerous cells appear to degrade local networks to the point where other brain regions must be recruited to complete cognitive tasks. While this compensatory recruitment can sustain function temporarily, it may come at a cost to efficiency and speed, contributing to slower thinking, word retrieval difficulties, and challenges with complex problem solving as the disease progresses.