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Measuring the active brain

Lecture: A new set of paradigms and machine learning algorithms to understand single-pulse electrical stimulation in the human brain

Speaker: Dr. Dora Hermes Miller and Dr. Kai Miller, Mayo Clinic, Rochester, USA

Venue: TU Berlin, Main building, Straße des 17. Juni 135, 10623 Berlin, Room: H 1028

Date & time: June 15/2022, 3 pm

Title: A new set of paradigms and machine learning algorithms to understand single-pulse electrical stimulation in the human brain

Abstract: Brain networks can be explored by delivering brief pulses of electrical current in one area while measuring voltage responses in other areas. We outline a set of paradigms to study these data, beginning with a “convergent” paradigm to study brain dynamics, focusing on a single brain site to observe the average effect of stimulating each of many other brain sites. Viewed in this manner, visually-apparent motifs in the temporal response shape emerge from adjacent stimulation sites. This work constructs and illustrates a data-driven machine learning approach to determine characteristic spatiotemporal structure in these response shapes, summarized by a set of unique “basis profile curves” (BPCs). Each BPC may be mapped back to underlying anatomy in a natural way, quantifying projection strength from each stimulation site using simple metrics. We then illustrate how this BPC formulation is useful for understanding projections to the collateral sulcus from limbic and temporal lobe structures. Our work then transitions to a “divergent” paradigm, describing a new type of parameterization of single pulse responses that we call “canonical response parameterization” (CRP). The CRP approach allows for robust statistical characterization of stimulation responses, regardless of what the shape of the response is. Our techniques are demonstrated for an array of implanted brain surface electrodes in human patients. These frameworks enable straightforward interpretation of single-pulse brain stimulation data, and can be applied generically to explore the diverse milieu of interactions that comprise the connectome.


Dora Hermes Miller, Ph.D., studies the signals measured in the living human brain in order to identify biomarkers of neurological and neuropsychiatric diseases and develop neuroprosthetics to interface with the brain. There are many different ways to measure the function of the living human brain, such as magnetic resonance imaging (MRI) and field potential recordings. Dr. Hermes uses a human systems neuroscience approach, including multimodal imaging and computational modeling, to advance fundamental understanding of the signals that can be measured in the human brain. Electrical stimulation and brain-machine interfaces are used to influence neuronal population activity and understand whether it is possible to restore typical brain function in neurological and neuropsychiatric diseases.

Dr. Hermes collaborates with neurologists and neurosurgeons to understand the extent to which smart sensing (predicting and stimulating brain activity) can result in new therapeutic devices that control epileptic brain activity.

Kai J. Miller, Ph.D., M.D., Ph.D., is a pediatric and adult neurosurgeon who specializes in brain tumors, epilepsy, and deep-brain stimulation. He manages patients in both in the operating room and in the outpatient setting. His research involves measuring electrical brain activity with patients undergoing therapy with implanted electrodes, to understand brain circuit dynamics and develop new therapies. In addition to brain tumors, epilepsy, and deep brain stimulation, Dr. Miller manages and treats general pediatric neurosurgical conditions.
On top of his active clinical and research programs, Dr. Miller teaches graduate students and mentors neurosurgical residents.