The recent discovery of direct and indirect glutamatergic communication between neurons and a subpopulation of brain tumour cells that drive brain tumour progression in high-grade pediatric and adult gliomas as well as breast cancer brain metastases shows the importance of neuronal activity on brain tumour progression. Mapping these interactions across whole tumors with correlative phase contrast imaging and light microscopy to create a tumor cell atlas will advance our understanding of glioma pathophysiology and help craft novel approaches to target this intractable disease.