Spatially Restricted Immature Neuronal Programs Drive Functional Connectivity in Glioblastoma

Glioblastoma (GB) integrates into the human brain by exploiting spatially restricted neuronal microenvironments at tumor margins. Combining magnetoencephalography-based functional mapping in patients with GB, spatially resolved biopsies, single-cell RNA sequencing, spatial transcriptomics, and electrophysiological profiling in human cortical slice models, we identify peritumoral connectivity hubs enriched for synaptogenic and immature neuronal programs. Connectivity-rich regions preferentially involve projection-capable excitatory neurons and display convergent activation of the WNK-SPAK-NKCC1 chloride homeostasis, consistent with a reduction in inhibition via GABAergic transmission in peritumoral neurons. GB-conditioned neurons exhibit developmental regression, impaired inhibitory control, and immature dendritic spine remodeling while network-level recordings reveal a GABA-sensitive reorganization of circuit topology. NKCC1 blockade reduces tumor-neuron synaptic integration and dampens functional network connectivity. Clinically, peritumoral degree centrality is an independent predictor of survival beyond established covariates. These findings establish neuronal immaturity as a functional substrate for tumor-neuron connectivity and define actionable biomarkers and pathways at the tumor-brain interface.