A closed loop feedback system for automatic detection and inhibition of mechano-nociceptive neural activity

Clinical studies have shown that spinal or cerebral neurostimulation can significantly relieve pain. Current neurostimulators work in an open loop; hence, their efficacy depends on the patient's or physician's comprehension of pain. We have proposed and developed a real-time automatic recognition program with signal processing functions to detect action potentials. By using a wireless neurorecording module, spinal neuronal responses to mechanical stimuli (brush, pressure, and pinch) applied to rats' hind paws were recorded. Nociceptive spinal responses were detected and suppressed by our automated module through delivering electrical stimulation to the periaqueductal gray (PAG). The interspike intervals (ISIs) of the fired action potentials were used to distinguish among the three different mechanical stimuli. Our system was able to detect the neuronal activity intensities and deliver trigger signals to the neurostimulator according to a pre-set threshold in a closed-loop feedback configuration, thereby suppressing excessive activity in spinal cord dorsal horn neurons.