Decoding Brain States with EEG
Funding: Army Research Laboratory
Student: Jason Ki
Collaborators: Lucas Parra
The ability to faithfully measure human cognitive state would find immediate application in multiple settings (e.g. the control room and navigation environments). Our central hypothesis is that cognitive state modulates the reliability of sensory processing, as measured by the correlation between stimulus features and neural activity. Preliminary data from our group indicates that attentional state and task difficulty modulate the reliability of EEG. These findings were enabled by the development of a new regression technique for measuring the reliability of neural responses. A related hypothesis is that being actively engaged with a stimulus leads to fundamentally different neural responses than when passively observing it. The goal of this work is to increase our understanding of how the brain represents its environment in real-world settings, while also advancing the state-of-the-art in brain-state monitoring.
Shown is the correlation between a video game stimulus and evoked EEG activity experienced in two different modes: actively playing the game (with a brain-computer interface) versus passively watching the game.
Transcranial Laser Stimulation
Student: Gazi Inkiyad
Collaborators: Greg Dmochowski and Hanli Liu
The brain makes up only 5% of the body’s mass, yet consumes over 20% of the its energy. In order to metabolize glucose and generate ATP, the brain requires a steady supply of oxygen in its blood supply. Deficits in cerebral blood flow and oxygenation are associated with ischemic stroke and several neurodegenerative disorders. We are investigating the use of near-infrared light to increase cerebral oxygenation. The experiments involve applying low levels of coherent light (i.e., lasers) to the brain transcranially.
Funding: National Institutes of Health (National Institute on Drug Abuse)
Students: Duc Nguyen, Destiny Berisha
Collaborator: Elisa Konofagou (Mentor)
(collaboration with Elisa Konofagou). Existing techniques for stimulating the brain using electromagnetic fields are limited in spatial resolution and penetration depth. The human skull greatly attenuates low-frequency electric fields, resulting in weak stimulation of the cortex. This has arguably led to the variable and generally insufficient results in TMS and TDCS research. In principle, ultrasound waves can overcome these limitations: ultrasonic waves have already been shown to be focused through the human skull in high-intensity applications for neurosurgery. The same focusing can be applied in a low-intensity regime to achieve targeted neuromodulation of cortical and subcortical brain structures. We are investigating ultrasound as a tool to interrogate brain circuits, beginning with experiments in rodents. The effects of the stimulation are monitored using electrophysiological recordings.