CMU Neural Engineering Virtual Seminars
Seminar Title: Volume Control for a Cortical Network
Speaker: Dr. Gene Y. Fridman, Professor, Johns Hopkins University
Abstract: Excitability is a fundamental property of cortical networks, shaping their responses to input. Here, we use ionic direct current (iDC) to modulate excitability with sub-10-ms temporal resolution and submillimeter spatial precision across the cortical surface, greatly surpassing the capabilities of pharmacological tools. In anesthetized rats, we recorded laminar neural responses in the S1HL cortex to spontaneous delta oscillations and to foot stimulation with and without iDC delivered to the cortical surface. Cathodic iDC suppressed, and anodic iDC enhanced, evoked responses across recording sites. iDC shifted the spatiotemporal excitability pattern in a graded manner, paralleling the effects of weaker or stronger foot stimuli. A computational model reproduced these effects and implicated dendritic summation at the axon initial segment (AIS) as a key mechanism for bidirectional modulation. This approach enables precise, causal manipulation of cortical responsiveness in vivo and offers a platform for dissecting functional circuits and developing targeted neurotherapeutic interventions.
About the Speaker: Dr. Gene Fridman is a Professor of Otolaryngology Head and Neck Surgery and Biomedical Engineering at Johns Hopkins University in Baltimore, MD. He is a Biomedical and Electrical engineer. He received his Ph.D. in Biomedical Engineering specializing in neural recording and stimulation and micro-electro-mechanical systems (MEMS) from UCLA in 2006. Since 2000 he has held an on-going consulting and collaborative relationship with biomedical engineering companies in research and design of neural stimulation and recording devices. He contributed to research and development of spinal cord, retinal, cortical, cochlear, DBS, and vestibular neural implants. His main scientific interest is in recording and stimulation implantable technologies. Dr. Fridman runs the Machine Biointerface Lab that currently focuses on the use and the development of the Freeform Stimulator technology to safely interact with neurons using arbitrary (non-pulsatile) waveforms for novel applications and scientific inquiry.