MindEx consists of two Neuroport Multi-Port Arrays, described in detail in the intervention description. Each NeuroPort Multi-Port Array comprises two electrode arrays implanted into human brain tissue, for a total of four electrode arrays. These will be in 1) prefrontal cortex, a brain area involved in scene comprehension, action selection, and error signaling, 2) premotor cortex, a brain area involved in planning ongoing and upcoming actions, 3) posterior parietal cortex, a brain area involved in processing sensory-to-motor transformations during movements, and 4) primary motor cortex, responsible for controlling movement. The pair of electrode arrays in each NeuroPort Multi-Port Array connect to a single percutaneous pedestal attached to the skull during a surgical procedure. Following recovery from the surgical placement, subjects will participate in study sessions up to 5 times a week. They will learn to use thought to control applications on a computer, a laptop, or a tablet.

NeuroPort Multi-Port Arrays allow for the local recording of cerebral cortex. The Mind Extender (MindEx) system is primarily composed of two NeuroPort Multi-Port Arrays. Each Multi-Port device consists of two arrays, each with 100 electrodes in a 10 x 10 configuration, with dimensions 4 mm x 4 mm x 1.5 mm (W x H x D), and a titanium percutaneous connector, 19 mm diameter at the base. Each MultiPort can have a total of 128 active channels (capable of transmitting neural signals to the percutaneous connector) across the two arrays. In our design, we will split active channels evenly between the two arrays resulting in 64 active channels per array. The four arrays of the two Multi-Port device will be implanted into prefrontal cortex, premotor cortex, primary motor cortex, and posterior parietal cortex.

A primary objective of this study is to evaluate the effectiveness of the system in providing users the ability to continuously move a cursor on a tablet/computer.

The hypothesis is that trajectory readability from neural signals will be significantly greater than the level of chance.

Standardized tests will be used to test this objective, and performance will be compared to the level of chance.

One example of a standardized test to be used is the accuracy of continuous trajectory decoding measured by the radial-8 assessment task.

Serious adverse events (SAE) will be evaluated against a 1% threshold level. We will use regular inspection of the subjects' scalps to assess for breakdown, discharge, or infection, and use history and physical exam to evaluate for new symptoms, and compare to baseline assessments.

An underlying hypothesis in this study is that the system will enable users the ability to control a computer/tablet interface by selecting icons.

An underlying hypothesis in the study is that neural signals will enable decoding the chosen target at higher accuracy than the level of chance.

Standardized tests will be used to test this objective, and performance will be compared to the level of chance.

An example of a standardized test to be used is the brain-control for tablet test (BCTT) which grades the accuracy of target selection by mental fixation to the level of chance.

An objective of this study is to determine whether the combination of neural signals from multiple brain regions in brain-computer interface control is more advantageous than from a subset of the brain regions being tested.

The hypothesis is that because the four brain regions being implanted each encode different cognitive functions, their integration will be more useful to brain-computer interface control, than any subset of these regions.

This objective will be tested by standardized tests (such as those mentioned for "Competency in computer/tablet control" and "Continuous trajectory decoding") in different groups of brain regions and reported for each, such as:

1. All four brain regions: prefrontal cortex (PFC), posterior parietal cortex (PPC), dorsal premotor cortex (PMd), primary motor cortex (M1)
2. PMd,PPC, and M1
3. PPC and M1 alone

The functional change in quality of life will be evaluated through a Quality-of-Life Inventory (QOLI) administered periodically throughout the study. This is a 32-item questionnaire with a score range from 1-77, with higher scores reflecting higher satisfaction.