Tag: brain-computer interface

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A novel robot-assisted method for implanting intracortical sensorimotor devices for brain-computer interface studies

J Neurosurg 142:1280–1288, 2025

A novel robot-assisted method for implanting intracortical microelectrode arrays in brain-computer interface studies was successfully demonstrated in a tetraplegic participant. The technique ensured precise placement, facilitating high-quality signal communication for motor control and sensory feedback, with promising implications for restoring upper-limb function.

• A novel robot-assisted method for implanting intracortical microelectrode arrays in brain-computer interface (BCI) studies is presented, focusing on surgical techniques and challenges.

• The technique was applied in a 31-year-old male with tetraplegia, enabling 2D control of a virtual arm with high success rates and maintaining recording quality over time.

• The robotic neurosurgery technique provides high accuracy and time efficiency, reducing human error and surgeon burden in repetitive procedures.

• Preoperative imaging and robotic systems were used for precise planning and execution of array implantations, ensuring minimal cortical damage and high signal quality.

• The study demonstrated that robotic neurosurgery could be successfully translated into BCI device implantation, aiming to restore upper-limb function.

• Future challenges include refining insertion methods, increasing automation, and addressing intraoperative adjustments for microvessels.

• The study was conducted under an investigational device exemption from the US Food and Drug Administration and received institutional review board approval.

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Classification of Individual Finger Movements Using Intracortical Recordings in Human Motor Cortex

Neurosurgery, Volume 87, Issue 4, 1 October 2020, Pages 630–638

Intracortical microelectrode arrays have enabled people with tetraplegia to use a brain–computer interface for reaching and grasping. In order to restore dexterous movements, it will be necessary to control individual fingers.

OBJECTIVE: To predict which finger a participant with hand paralysis was attempting to move using intracortical data recorded from the motor cortex.

METHODS: A 31-yr-old man with a C5/6 ASIA B spinal cord injury was implanted with 2 88- channel microelectrode arrays in left motor cortex. Across 3 d, the participant observed a virtual hand flex in each finger while neural firing rates were recorded. A 6-class linear discriminant analysis (LDA) classifier, with 10 × 10-fold cross-validation, was used to predict which fingermovement was being performed (flexion/extension of all 5 digits and adduction/abduction of the thumb).

RESULTS: Themean overall classification accuracywas 67% (range: 65%-76%, chance: 17%), whichoccurredat anaverageof 560ms (range:420-780ms) aftermovementonset. Individually, thumb flexion and thumb adduction were classified with the highest accuracies at 92% and 93%, respectively. The index, middle, ring, and little achieved an accuracy of 65%, 59%, 43%, and 56%, respectively, and, when incorrectly classified, were typically marked as an adjacent finger. The classification accuracies were reflected in a low-dimensional projection of the neural data into LDA space, where the thumb-related movements were most separable from the finger movements.

CONCLUSION: Classification of intention to move individual fingers was accurately predicted by intracortical recordings from a human participant with the thumb being particularly independent.

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A novel neural prosthesis providing long-term electrocorticography recording and cortical stimulation for epilepsy and brain-computer interface

J Neurosurg 130:1166–1179, 2019

Wireless technology is a novel tool for the transmission of cortical signals. Wireless electrocorticography (ECoG) aims to improve the safety and diagnostic gain of procedures requiring invasive localization of seizure foci and also to provide long-term recording of brain activity for brain-computer interfaces (BCIs). However, no wireless devices aimed at these clinical applications are currently available. The authors present the application of a fully implantable and externally rechargeable neural prosthesis providing wireless ECoG recording and direct cortical stimulation (DCS). Prolonged wireless ECoG monitoring was tested in nonhuman primates by using a custom-made device (the ECoG im- plantable wireless 16-electrode [ECOGIW-16E] device) containing a 16-contact subdural grid. This is a preliminary step toward large-scale, long-term wireless ECoG recording in humans.

METHODS The authors implanted the ECOGIW-16E device over the left sensorimotor cortex of a nonhuman primate (Macaca fascicularis), recording ECoG signals over a time span of 6 months. Daily electrode impedances were mea- sured, aiming to maintain the impedance values below a threshold of 100 KW. Brain mapping was obtained through wireless cortical stimulation at fixed intervals (1, 3, and 6 months). After 6 months, the device was removed. The authors analyzed cortical tissues by using conventional histological and immunohistological investigation to assess whether there was evidence of damage after the long-term implantation of the grid.

RESULTS The implant was well tolerated; no neurological or behavioral consequences were reported in the monkey, which resumed his normal activities within a few hours of the procedure. The signal quality of wireless ECoG remained excellent over the 6-month observation period. Impedance values remained well below the threshold value; the average impedance per contact remains approximately 40 KW. Wireless cortical stimulation induced movements of the upper and lower limbs, and elicited fine movements of the digits as well. After the monkey was euthanized, the grid was found to be encapsulated by a newly formed dural sheet. The grid removal was performed easily, and no direct adhesions of the grid to the cortex were found. Conventional histological studies showed no cortical damage in the brain region covered by
the grid, except for a single microscopic spot of cortical necrosis (not visible to the naked eye) in a region that had under- gone repeated procedures of electrical stimulation. Immunohistological studies of the cortex underlying the grid showed
a mild inflammatory process.

CONCLUSIONS This preliminary experience in a nonhuman primate shows that a wireless neuroprosthesis, with related long-term ECoG recording (up to 6 months) and multiple DCSs, was tolerated without sequelae. The authors predict that epilepsy surgery could realize great benefit from this novel prosthesis, providing an extended time span for ECoG recording.

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