Functional Brain Mapping – Interview with Dr. Kyousuke Kamada


Kyousuke Kamada has been professor and chairman of the Department of Neurosurgery at the Asahikawa Medical University in Hokkaido, Japan since 2010. His professional career includes research periods at the Hokkaido University, the University of Erlangen-Nürnberg and The University of Tokyo, and his main research includes functional brain mapping and brain-computer interfaces. Dr. Kamada, an expert for high-gamma mapping procedures, utilizes cortiQ to make functional brain maps in real-time. With cortiQ, he evaluates motor and even language-related functions at the bed side in the monitoring unit or in the operating room. Our researcher Christoph Kapeller had the chance to talk with Dr. Kamada about his experiences.

In what conditions do patients find themselves when they become a patient of yours?
Kyousuke Kamada: “Usually, patients we treat suffer from seizures and in some cases aphasia. A third common symptom involves consciousness disturbance, where patients feel drowsy. Most of the time, such cases are brought by their family to the hospital. These three symptoms are the most prominent ones.”

What kind of surgical procedures do you perform usually?
Kyousuke Kamada: “The procedures can be divided into epilepsy surgeries and brain tumor resections. For epilepsy surgery, we do functional brain mapping and 24 hours of video monitoring. After that, we have to resect only the epileptogenic foci. On the other hand, for brain tumor surgery, we perform imaging studies and then resect the brain tumor. Sometimes the tumor is located in a language area, which requires an awake craniotomy.”

What is the greatest challenge when operating directly on the brain? What is the most crucial part when performing surgical procedures?
Kyousuke Kamada: “Sometimes we have to touch the eloquent cortices, such as language or motor cortex. We have to locate these important areas very precisely, and therefore, we do need electro-physiological monitoring or electro-physiological mapping.”

You use the cortiQ system to map brain functions in real-time with electrocorticography or ECoG signals from subdural electrodes. Why is this important during surgery?
Kyousuke Kamada: “Of course the actual golden standard is electrical cortical stimulation (ECS), but sometimes ECS does not evoke observable symptoms. In such cases cortiQ mapping is a powerful alternative, since it can detect high gamma activation directly from the brain. Depending on the task, we can get a lot functional distributions of the brain for each case. So, first of all, we do need a rough brain mapping based on cortiQ. Then we can switch to the electro cortical stimulation. It helps a lot!”

Picture 1: cortiQ mapping during surgery.

What advantages do you have when mapping in real-time with cortiQ compared to conventional methods?
Kyousuke Kamada: “I think the cortiQ mappings are really fast. It takes only two minutes. If we do ECS mapping, sometimes we have some problems with seizures and one seizure takes probably more than 30 minutes. That’s the reason why we do a cortiQ mapping first. I think that is really helpful for the patient and also for us in the surgery. Also, ECS cannot reveal activity in some brain areas that cortiQ can detect.”

For your surgical procedures, you created one specific paradigm that includes four tasks, solve Rubik’s cube, read a story, listen to a story and perform calculations. Why did you choose these tasks, and which paradigms will come next?
Kyousuke Kamada: “It is important to create a simple and easy task for the mapping. Patients often suffer from symptoms like language deficits or drowsiness. Often they can just move the Rubik’s cube to activate motor areas or listening to a story to evoke Wernicke’s areas activation. Sometimes they can do a simple calculation, which activates the parietal lobe. With these tasks, we can easily detect activity in brain areas involved in these tasks.”

Picture 2: Patient solving a Rubik’s cube.

In one experiment, you let the patient perform three tasks, listen to a story, name pictures or read Kanji characters. What did you learn from this experiment?
Kyousuke Kamada: “By that time, we were using some letter types. Depending on the Japanese letter systems (alphabets), patients sometimes show activation on the temporal base (ventral temporal cortex). We learned that a temporal base mapping is really crucial for Japanese language and we have to identify this language area. However, it is difficult to electrically stimulate that area.”

Figure 3: cortiQ mapping results of three language related tasks. The red circles with the yellow border indicate significant high-gamma activation (p < 0.05) after Bonferroni correction. The tasks “Listen”, “Name the picture” and “Read the Kanji” took 15, 20 and 26 seconds, respectively, and were repeated three times.

Figure 4: ECS mapping results for language related functional regions on the cortex are represented by colored circles. The resected tumor is highlighted by the rounded rectangle.

What future trends do you see for surgeries with real-time mapping procedures?
Kyousuke Kamada: “In the future, we have to identify additional functions such as memory or more precise language mapping using high resolution electrode grids and investigating different frequency bands.”

Recently, you used the recoveriX system as a motor rehabilitation method after brain surgery. What was the condition of the patient before and after surgery?
Kyousuke Kamada: “This is really impressive. After only one day of recoveriX rehabilitation training, this patient reported better feeling. We also did a one-month experiment with recoveriX. The prognosis was really nice. We included MRI scanning, where we realized that the patient, who did the recoveriX training in this experiment, showed improved activation in the affected motor cortex.”

What results did you get after using recoveriX? Did the patient improve his motor function?
Kyousuke Kamada: “Yes absolutely. We had three patients with recoveriX training, and also three normal volunteers. Patients with recoveriX training improved more than others without recoveriX training. Still, the number of patients is pretty small, so we have to collect data from more patients, but I am sure that recoveriX will help us a lot in future rehabilitation.”

Dr. Kamada, thank you very much!