High resolution functional localization of epileptogenic focus with glutamate and electrical signals detection by ultramicroelectrode arrays

Abstract

Epileptogenic focus is the predominant brain area to form seizures, while it is very difficult to be located precisely with existing technology. Dual-mode neural signals involving neurotransmitter release and electrical signals for high resolution functional localization of epileptogenic focus accurately remains an unsolved tough problem. In this work, an implantable ultramicroelectrode array (UMEA) with high resolution was fabricated for epileptogenic focus functional localization based on multiple neural activities involving glutamate concentration, neural spike pattern and local field potential (LFP) power. A higher signal to noise ratio (D = 1 μm, S/N = 7.93) is obtained comparing with our previous microelectrodes (D = 25 μm, S/N = 3.39). Abnormality occurred in the epileptic brains even without seizure by comparing with normal ones. The subcellular recording of neural activities from cortex to thalamus demonstrated that a higher value of Glu concentration, spike firing rate, spike amplitude and LFP power is obtained at hippocampus CA3 and dentate gyrus (DG) than other regions, which is considered as the origination of epileptogenic focus. This dual-mode neural activities used for functional localization at high spatiotemporal resolution, especially with the release of neurotransmitter, provide us with a platform for high-precision surgical planning and treatment.