Microgrid II - Electrocorticography Signals for Human Hand Prosthetics

Stroke, spinal cord injury, extremity injury and degenerative/locked-in syndromes are among
those conditions that may benefit from sustainable neuroprosthetic options. The investigators
have studied human motor cortex and related cortical areas with direct brain recording
(electrocorticography or ECoG) as a signal for motor neuroprosthetics. Completing exciting
studies in humans with local fields using intracortical electrodes and long-term working
brain-computer interfaces with EEG, electrocorticography surveys an intermediate level of
spatial specificity and may have durability in long-term recordings. ECoG signals could
ultimately be obtained epidurally or even more superficially if the exact signals were better
understood. To date, the investigators have demonstrated that ECoG signals from motor cortex
can be used to decode movement and have a precision using clinic arrays (1 cm resolution)
that can decode hand movement and allow for the separation of digit movement. These signals
have been used for brain-computer interface and can be used to control a prosthetic hand in
humans.

Electrocorticography (ECoG) is the recording of brain signals directly from the cortical
surface. In patients undergoing surgical treatment of epilepsy, these signals have been
available and have shown to be rich sources of motor-related signals that can drive a hand
neuroprosthetic as part of a brain-computer interface (BCI). Though the clinically available
resolution of 1 cm allows for separation of different types of finger movement by using the
high-frequency characteristics of the ECoG recording (70-100Hz), higher spatial resolutions
(3mm) increases the ability to decode finger movements and more complicated hand movements,
such as grasping of different objects. Ideal resolution is one of the several gaps in
knowledge limit pursuing implementation of ECoG-based BCI along with uncertainty about the
longevity of ECoG signals and human implementation of feedback directly to cortex through
electrical stimulation.

Specific Aim:

Higher resolution arrays over subacute (1 week) time frame to allow for adaptation and BCI
use of the higher resolution signals. An 8x8 array of 3mm resolution will be placed over
sensorimotor cortex. Grasp synergies will be determined and mapped onto the electrodes to
determine control channels for each synergy. Control of multiple synergies will move a
simulated robotic hand to a visually cued target shape

1. Hand synergies will be independently mapped onto the 3mm x 3mm (microarray) with at
least one independent electrode for each of the first three synergies

2. Using the signals from the microarray, participants will correctly move the robotic hand
into one of 6 target postures with 50% accuracy.

Inclusion Criteria:

- Must be able to speak and read English

- Cognitive ability to follow study directions

- Patients that are scheduled to undergo grid placement clinically for treatment of

- intractable epilepsy

- 18 years of age or older

Exclusion Criteria:

- Patients who are not considered candidates for epilepsy surgery

- Individuals who have a diagnosis that would not allow them to participate in research
procedures. For example, a physical disability that would limit hand movements and
range of motion.