Two rhesus macaques were trained to perform the functionally unconstrained reach-return arm movements, while high-density ECo G or local field potential (LFP) signals were recorded from the PMv area (Fig. Overall, the food reach-return accuracy of the two monkeys was 99.4%, the reach duration was 1050 ± 290 ms, and the return duration was 590 ± 200 ms.
Through the time-frequency analysis of ECo G and LFP oscillations, the entire frequency spectrum was divided into three frequency bands according to the similar characteristic modulation during the movement tasks: (1) low-frequency band (less than 9 Hz); (2) intermediate-frequency band (9–40 Hz); and (3) high-frequency band (greater than 40 Hz).
Overview of the experimental design and 3D rendered illustration of unconstrained arm movements.
(A) The position of high-density ECo G array in the monkey’s left hemisphere.
There is also no information on how high-density ECo G signalsmay be potentially used in the PMv for BMI control.
Since patients’ paralyzed limbs cannot move, the awake-behaving non-human primate model is a good pre-clinical model for developing such a cortically-controlled movement paradigm.
High-density ECo G-based BMIs have been used to classify individual finger movements.
We found that neural activity from a small number of electrodes within the PMv can be used to accurately predict reach-return movement onset and directionality.Movement trajectories from XZ and YZ planes were recorded using two cameras, respectively. Colorful dots were used to distinguish the distal (wrist joint with green color), middle (elbow joint with red color), and proximal portions (shoulder joint represent by triceps with blue color) of the right upper limb of monkey.The wireless recording system received the ECo G signals from the monkey’s head stage, and transmitted these signals to the data acquisition system. The lines connected dots represent the forearm and the upper arm abstractly.Red dots represent the 32 electrodes; the black line indicates the central sulcus (CS) of the left hemisphere.(B) Schematic diagram showing the experimental configuration of the reach-return task, where monkey was trained to reach for food offered by the experimenter in three-dimensional space without explicit cues; top-down view depicts the body-centered X-Y coordinates; the Z coordinate is perpendicular to the horizontal plane.(C) Starting position of the monkey’s right arm while perched. Using the ECo G signal from monkey T, we observed a longer-lasting reduction of power amplitudes (event-related desynchronization, ERD) starting well before and ending after reach-return movements, in the intermediate-frequency band range (9–40 Hz).In a broad band of high-frequency signals from 40 Hz up to 200 Hz, a consistent amplitude increase (event-related synchronization, ERS) was observed before the movement onset during the movement period (Fig. Spectrograms showing the time- and frequency-resolved amplitude spectra of reach-return movement from one representative PMv channel (Channel 10).Brain-machine interface (BMI) techniques can provide an indirect bridge between the brain and intact limbs and/or an external prosthetic device.By partially restoring lost motor function, BMIs may improve a patients’ ability to directly interact with their environment and provide a higher quality of life.Motor paralysis can be secondary to a disruption in the neural pathways between the brain and muscle without disrupting normal cognitive ability.Indeed many patients suffer from diseases, such as spinal cord injury, amyotrophic lateral sclerosis and cerebral palsy, but retain motor cortical circuitries necessary for planning and orchestrating movement.