A digital wireless system for closed-loop inhibition of nociceptive signals

Abstract

Neurostimulation of the spinal cord or brain has been used to inhibit nociceptive signals in pain management applications. Nevertheless, most of the current neurostimulation models are based on open-loop system designs. There is a lack of closed-loop systems for neurostimulation in research with small freely-moving animals and in future clinical applications. Based on our previously developed analog wireless system for closed-loop neurostimulation, a digital wireless system with real-time feedback between recorder and stimulator modules has been developed to achieve multi-channel communication. The wireless system includes a wearable recording module, a wearable stimulation module and a transceiver connected to a computer for real-time and off-line data processing, display and storage. To validate our system, wide dynamic range neurons in the spinal cord dorsal horn have been recorded from anesthetized rats in response to graded mechanical stimuli (brush, pressure and pinch) applied in the hind paw. The identified nociceptive signals were used to automatically trigger electrical stimulation at the periaqueductal gray in real time to inhibit their own activities by the closed-loop design. Our digital wireless closed-loop system has provided a simplified and efficient method for further study of pain processing in freely-moving animals and potential clinical application in patients.

Role for the Ventral Posterior Medial/Posterior Lateral Thalamus and Anterior Cingulate Cortex in Affective/Motivation Pain Induced by Varicella Zoster Virus

“…In Experiment 3, LFP recordings were made using a customized wireless recording module (Zuo et al, 2012 ) attached to a recording electrode implanted directly into the VPM/VPL and ACC. LFP was recorded using a low pass filter of 100 Hz.…”

“…Before recording the rats were briefly (5 min) anesthetized with 2% isoflurane and fitted with a backpack containing the LFP customized wireless recording module (Zuo et al, 2012 ) and then the module was connected to the recording electrode. After waking from anesthesia a 10 min LFP “Baseline” was recorded.…”

An Implantable Wireless Neural Interface System for Simultaneous Recording and Stimulation of Peripheral Nerve with a Single Cuff Electrode

“…Hence, extra devices are required for the more sophisticated experiments where concurrent neural stimulation and recording are required. The neural interface devices introduced in [ 51 , 52 ] are equipped with both functions of neural recording and neural stimulation by using separated modules. However, it is difficult to implant the separated modules with a large size into the limited inner space of a body.…”

Spinal Stimulation for Pain: Future Applications

“…The presence and details of compound action potentials may be revealed by recording from the implanted epidural stimulation electrodes. This has already been done in animals [22] and in a small group of SCS patients [23]. One of the findings suggested a correlation between depression in evoked compound action potentials (ECAP) and thresholds for stimulation [22], which may help in finding the best position for SCS electrodes, but-most remarkably-the in vivo recordings in patients undergoing stimulation revealed a correlation between Aβ ECAP amplitude and the degree of coverage of the painful area [23].…”

“…This has already been done in animals [22] and in a small group of SCS patients [23]. One of the findings suggested a correlation between depression in evoked compound action potentials (ECAP) and thresholds for stimulation [22], which may help in finding the best position for SCS electrodes, but-most remarkably-the in vivo recordings in patients undergoing stimulation revealed a correlation between Aβ ECAP amplitude and the degree of coverage of the painful area [23]. This amplitude of Aβ ECAP is a measure of the level of neuronal recruitment, which may become a feedback parameter for continuous optimization of neuromodulation parameters [23].…”