Functional Brain Mapping – Interview with Dr. Gerwin Schalk

Gerwin Schalk is Research Scientist at the Wadsworth Center in Albany, New York, and an Associate Professor at Albany Medical College.He is developing new neurotechnologies, and applying them to basic and applied research. We had the chance to talk to Gerwin about his work with cortiQ and the use of ECoG (electrocorticography) to understand and revolutionize surgical treatment of the brain.

Gerwin, can you explain shortly why brain mapping is crucial for epilepsy or tumor resections? How do physicians prepare for brain surgery?
Gerwin Schalk: “Surgical planning relies on the delineation of pathological and functional brain areas.  Pathological tissue is often identified through neuroimaging or visual inspection of the anatomy or of brain signals recorded from different areas.  Functional or eloquent brain areas, i.e., areas in the brain that are responsible for allowing us to move or speak, cannot readily be identified visually.  There are traditional methods to identify those areas (most notably, electrical stimulation of the brain), but these methods have substantial downsides.”


Figure 1: cortiQ allows you to position the used electrode grids (selected from the grid library) over a schematic brain map. For different tasks performed by the patient (e.g. using the Ritaccio paradigm), high gamma activity is indicated in form of red circles for all electrodes. A big red circle shows that the corresponding electrode is placed over a brain area which is highly active in the performed task.

What advantages does ECoG-based brain mapping have for surgeons and patients?
Gerwin Schalk: “ECoG-based functional mapping takes much less time than the traditional method of electrical stimulation (minutes vs. hours), and does not increase the risk of epileptic seizures or other complications.”

Functional Brain Mapping is mostly used for epilepsy and tumor resections. How will this field change in the future?
Gerwin Schalk: “Brain mapping has remained largely the same for several decades.  This situation is now rapidly changing.  g.tec is part of a revolution that is bringing a number of important new technologies to the clinicians and their patients worldwide.”

electrical-stimulation-gerwin-schalk-1Figure 2: (ECS) is used to verify the correct electrodes incorporated in a specific task or action. Multiple grids and strips are often used to cover large cortical areas (Gerwin Schalk, Wadsworth Center, USA).

Patients have to be awake during surgery sometimes. Does this apply to functional mapping procedures with ECoG? What are the advantages of brain mapping compared to conventional brain mapping methods (such as cortical electrical stimulation)?
Gerwin Schalk: “ECoG-based brain mapping has particular advantages for awake surgeries, in particular because of the time limitations inherent in the surgical procedure.  Because it only takes minutes rather than hours, it can readily be performed during most awake surgeries.”

What regions of the brain are especially interesting for brain mapping?
Gerwin Schalk: “The regions in the brain that surgeons pay particular attention to are those that make us move or speak.  Even though all areas in the brain are important, the possibility of losing motor or language function is particularly disconcerting for most people, and this risk needs to be avoided if at all possible.”

What are your experiences with cortiQ?
Gerwin Schalk: “Real-time functional brain mapping with cortiQ is not only critical for clinical evaluations prior to invasive brain surgery, it is also an invaluable tool for scientific research that is based on electrocorticographic (ECoG) signals. Because the time that is available with ECoG subjects is very limited, it is important to optimize experimental testing based on the specific electrode montage over each subject’s brain. We use cortiQ to rapidly determine the functional significance of the covered electrode locations. Thus, cortiQ-based mapping allows us to be more efficient in our ECoG-based research.”

gerwin-schalk-1Gerwin Schalk is interested in technical innovation at the intersection of neuroscience, engineering, and clinical domains. His main research is the development and application of novel techniques to study brain function using signals recorded from the surface of the brain (electrocorticography (ECoG)), and the application of the resulting understanding to important clinical problems. Therefore, Schalk investigates the neural basis of motor, language, and cognitive function by applying computational techniques to recordings from the surface of the brain via electrocorticography (ECoG). His work has been published in numerous scientific publications.

10th International Workshop on Advances in Electrocorticography
November 10th – 11th , 2016 in San Diego, California, USA