Imaging fast electrical activity in the brain with electrical impedance tomography

• Published in: NeuroImage (Orlando, Fla.) Vol. 124; no. Pt A; pp. 204 - 213
• Main Authors: Aristovich, Kirill Y., Packham, Brett C., Koo, Hwan, Santos, Gustavo Sato dos, McEvoy, Andy, Holder, David S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2016; Elsevier Limited; Academic Press
• Subjects: Animals; Brain research; Brain Waves; Conflicts of interest; Electric Impedance; Electrodes; Electrodes, Implanted; Electroencephalography - methods; Evoked Potentials, Somatosensory; Female; Image Processing, Computer-Assisted - methods; Medical imaging; Microelectrodes; Models, Neurological; Rats; Rats, Sprague-Dawley; Rodents; Signal Processing, Computer-Assisted; Somatosensory Cortex - physiology; Tomography - methods; Touch Perception - physiology; Ventilation
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2015.08.071

Imaging of neuronal depolarization in the brain is a major goal in neuroscience, but no technique currently exists that could image neural activity over milliseconds throughout the whole brain. Electrical impedance tomography (EIT) is an emerging medical imaging technique which can produce tomographic images of impedance changes with non-invasive surface electrodes. We report EIT imaging of impedance changes in rat somatosensory cerebral cortex with a resolution of 2ms and <200μm during evoked potentials using epicortical arrays with 30 electrodes. Images were validated with local field potential recordings and current source-sink density analysis. Our results demonstrate that EIT can image neural activity in a volume 7×5×2mm in somatosensory cerebral cortex with reduced invasiveness, greater resolution and imaging volume than other methods. Modeling indicates similar resolutions are feasible throughout the entire brain so this technique, uniquely, has the potential to image functional connectivity of cortical and subcortical structures. •EIT can be used for imaging neural activity with <200μm and <2ms resolution.•EIT features significantly correlate with CSDA.•The spatiotemporal trajectory of activity can be traced using EIT.•Imaging can be extended to the entire rat brain with a resolution of <500μm.