Under the direction of Dr. Nathan Crone, the JHU Cognitive Neurophysiology and BMI Lab is working to identify and validate electrophysiological signatures of human cortical processing and to use them to study the neural mechanisms of motor, sensory, and language functions. Where applicable, we are applying this understanding to the development of assistive systems for individuals with disabilities.
We developed a novel system, the Hybrid Augmented Reality Multimodal Operation Neural Integration Environment (HARMONIE). This system utilizes hybrid input, supervisory control, and intelligent robotics to allow users to identify an object (via eye tracking and computer vision) and initiate (via brain-control) a semi-autonomous reach-grasp-and-drop of the object by the JHU/APL Modular Prosthetic Limb MPL. The novel approach demonstrated in this proof-of-principle study, using hybrid input, supervisory control, and intelligent robotics, addresses limitations of current BMIs.
During the cued production of words, a temporal cascade of neural activity proceeds from sensory representations of words in the temporal cortex to their corresponding articulatory gestures in the motor cortex. Broca's area mediates this cascade through reciprocal interactions with temporal and frontal motor regions. Contrary to classic notions of the role of Broca's area in speech, while the motor cortex is activated during spoken responses, Broca's area is surprisingly silent. Moreover, when novel strings of articulatory gestures must be produced in response to nonword stimuli, neural activity is enhanced in Broca's area, but not in the motor cortex. These unique data provide evidence that Broca's area coordinates the transformation of information across large-scale cortical networks involved in spoken word production. In this role, Broca's area formulates an appropriate articulatory code to be implemented by the motor cortex.
The directionality and intensity of high frequency activity (70-175 Hz) propagation was estimated during ictal and interictal recordings. These analyses revealed prominent divergence and convergence of activity propagation at sites identified by epileptologists as part of the ictal onset zone. In patients with focal ictal onsets, the patterns of propagation recorded during pre-ictal and interictal intervals were very similar to those recorded during seizures. The ability to characterize epileptogenic networks interictally could have important clinical implications by reducing the need for prolonged invasive monitoring to record spontaneous seizures.