Brain Imaging Research at the NYU Comprehensive Epilepsy Center

By Thomas Thesen

Chronic epilepsy can have profound influences on the cognitive performance of patients across their life-span. The Cognitive Neurophysiology Research Group at the NYU Comprehensive Epilepsy Center studies sensation and cognition in the human brain in health and disease using novel and sophisticated neuroimaging techniques. The young and active research team is headed by Thomas Thesen, Ph.D. and Chad Carlson, M.D., both Assistant Professors in the Department of Neurology, and collaborates directly with many other members of the Epilepsy Center. The goal of the research group is to investigate how the healthy brain processes sensory and cognitive information, such as language, memory and decision-making amongst others, and to understand what happens when these functions break down in patients with epilepsy. The group, consisting of basic scientists and clinical practitioners, has a special emphasis on translational research: moving state-of-the-art brain imaging techniques from the laboratory into the clinical practice, and at the same time using the clinical environment to generate novel hypotheses about brain function that can be tested in the laboratory. A major goal of the research group is to advance the understanding of cognition in epilepsy in order to help patients preserve and regain their cognitive abilities to enable them to live rich and fulfilling lives.

MRI Brain Morphometry

To study the relationship between brain structure and cognition, the researchers are using high-resolution MRI scans from healthy controls and epilepsy patients. These scans are analyzed with a novel and automated 3D whole-brain segmentation procedure for obtaining delineations of different neuroanatomical structures, including hippocampus, amygdala, thalamus, cerebellum, caudate, putamen, and globus pallidus and ventricles. This technique also measures the thickness of the cortical mantle at every point in the cerebral cortex, a metric which is especially relevant to seizures originating outside the mesial temporal lobes.
The MRIs of individual patients can thus be compared to a group of healthy individuals to detect small, but significant, changes in brain anatomy related to the patient’s epilepsy. These malformations can often cause seizures, but once detected and localized, they prove to be formidable targets for surgery because their removal carries a high chance of achieving seizure freedom. Current routine clinical MRIs rely on visual inspection and are not able to detect subtle malformations. This new method, developed with support from faces, allows for exact quantification and comparison of brain anatomy and has already shown to be more sensitive and reliable to detect disease-related changes in brain structure than conventional approaches. A better diagnosis leads to better treatment.

Mapping of brain function for presurgical evaluation

For patients with medically intractable epilepsy, surgery is often the last hope for obtaining seizure freedom. A comprehensive evaluation prior to surgery, including mapping of brain functions are often essential for success. We are using non-invasive functional MRI and Magnetoencephalography (MEG) along with task paradigms that conform to the current standards in cognitive neuroimaging to study and localize areas in the brain that are associated with language, memory, movement and touch. These assessments help the clinical and neurosurgical team to better ensure that the surgical procedure will only target epileptogenic regions without having an impact on the patient’s sensory and cognitive functions.
Intracranial EEG
Candidates for epilepsy surgery often undergo intracranial EEG monitoring where electrodes are placed inside the skull and directly on the brain. Many of the patients agree to participate in cognitive studies during their hospital stay, a decision which does not influence their clinical care and is conducted in strict accordance with the ethical guidelines of the University Medical Center. The NYU Comprehensive Epilepsy Center has the highest volume of epilepsy surgeries in the country.  Studying the human brain with intracranial EEG allows for the detection of brain activity with an unparalleled degree of spatial and temporal resolution. Over the past years we have assembled a consortium of high-profile collaborators from departments within NYU and other institutions, such as the University of California, San Diego and Harvard. Intracranial EEG studies conducted to date investigate a broad array of topics, such as memory, language, multisensory integration, face-perception and decision-making. We recently started work on brain computer interfaces, whereby a computer reads brain activity recorded from implanted electrodes and learns to interpret the signal.  With this mechanism, a computer cursors or artificial limbs can be controlled through mere ‘thinking’. Such a neural prosthetic device may help patients with paraplegia or locked-in syndrome in the future. The research team is very grateful to all patient volunteers who have devoted their time to help us understand more about the brain and epilepsy! Without them, none of this exciting research would be possible.