Closed-loop neuromodulation systems aim to treat a variety of neurological conditions by delivering and adjusting therapeutic electrical stimulation in response to a patient’s neural state, recorded in real time. Existing systems are limited by low channel counts, lack of algorithmic flexibility, and the distortion of recorded signals by large and persistent stimulation artifacts. We address these issues with a wireless artifact-free neuromodulation device (WAND) [1], [2] that enables research applications requiring high-throughput data streaming, low-latency biosignal processing, and simultaneous sensing and stimulation.

WAND system architecture. (a) The 3D CAD model of WAND with the primate headstage and battery pack. (b) Top- and bottom-view photographs of the WAND circuit board. (c) Micrograph of custom neuromodulation integrated circuit (NMIC) (Cortera Neurotechnologies [3]).

The device is an integrated and non-modular version of OMNI (see OMNI project) [4] with all its components (CM, AM, and two NMs) on a single board, enabling in-vivo expermients of the system. It is capable of closed-loop recording and stimulation on 128 channels, with on-board processing to fully cancel stimulation artifacts. In addition, it can detect neural biomarkers and automatically adjust stimulation parameters in closed-loop mode.

Residual artifact analysis and cancellation. (left) 1-second segments of baseline LFP with no stimulation (white), stimulation with no artifact cancellation (red), and stimulation with artifact cancellation (blue). (right) Spectrogram of full 90-second recording during the different stimulation phases.

In a behaving nonhuman primate, the device enabled long-term recordings of local field potentials and the real-time cancellation of stimulation artifacts, as well as closed-loop stimulation to disrupt movement preparatory activity during a delayed-reach task. The neuromodulation device may help advance neuroscientific discovery and preclinical investigations of stimulation-based therapeutic interventions.

(a) Overnight, untethered recording of brain signals from an NHP during sleep. (b) Delta (0.5–4 Hz) and theta (4–7 Hz) power from two-hour segment of overnight recording. K-means was used to classify the activity into states of increased (light blue background) and decreased (white background) delta and theta activity. (c) LFP recordings during center-out joystick task with timeline of task periods for movement and reward. Plotted beta power is aligned to the Go Cue, and each row represents activity from a single trial.

This project was a collaboration between several groups at UC Berkeley (Profs. Jan Rabaey, Elad Alon, Jose Carmena, and Rikky Muller) and Cortera Neurotechnologies.

  1. A wireless and artefact-free 128-channel neuromodulation device for closed-loop stimulation and recording in non-human primates A. Zhou, S. R. Santacruz, B. C. Johnson, G. Alexandrov, A. Moin, F. L. Burghardt, J. M. Rabaey, J. M. Carmena, and R. Muller Nature Biomedical Engineering 2018 [arXiv] [Link]
  2. WAND: A 128-channel, closed-loop, Wireless Artifact-free Neuromodulation Device A. Zhou, S. R. Santacruz, B. Johnson, G. Alexandrov, A. Moin, F. Burghardt, I. Izyumin, E. Alon, J. Rabaey, J. M. Carmena, and R. Muller In Society for Neuroscience (SfN) annual meeting 2017 [PDF]
  3. An implantable 700 \muW 64-channel neuromodulation IC for simultaneous recording and stimulation with rapid artifact recovery B. C. Johnson, S. Gambini, I. Izyumin, A. Moin, A. Zhou, G. Alexandrov, S. R. Santacruz, J. M. Rabaey, J. M. Carmena, and R. Muller In Symposium on VLSI Circuits 2017 [PDF]
  4. Powering and Communication for OMNI: A Distributed and Modular Closed-Loop Neuromodulation Device A. Moin, G. Alexandrov, B. C. Johnson, I. Izyumin, F. Burghardt, K. Shah, S. Pannu, E. Alon, R. Muller, and J. M. Rabaey In International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) 2016 [PDF]