An electromechanical stimulator system for neurophysiological and psychophysical studies of pain.
We have developed a computer-based electromechanical stimulator system suited for neurophysiological and psychophysical studies of pain. The core of the stimulator is a servo-controlled linear motor capable of generating 1 kg of force over a 22-mm range. Forces collinear and tangenital to the interchangeable probe tip are calculated using the signal from 3 load cells (resolution: 1/8 g; range: 250 g) arranged in an equilateral triangle. Probe position is measured with an optical encoder (resolution: 1 micron; range: 25 mm). A microprocessor-based digital control system permits smooth switching of feedback control between force or position at the 1-kHz update rate. The stimulator is mounted on a microprocessor-controlled 3-axis translation system that allows automatic movement of the probe over a range of greater than 15 cm to an accuracy of better than 10 microns. The stimulator can be programmed to move in a coordinate system parallel to the skin surface being examined. An IBM-compatible computer is used to command stimulus paradigms and to display real-time motor performance and neural spike-train data. The system has been used to measure the response of nociceptive afferents in monkey to controlled force stimuli applied to various positions within the receptive field.
Schneider
W
W
Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099, USA.
Slugg
R M
RM
Turnquist
B P
BP
Meyer
R A
RA
Campbell
J N
JN
D000818:Animals; D004558:Electric Stimulation / Q000295:instrumentation*; D005246:Feedback; D000882:Haplorhini; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D009619:Nociceptors / Q000502:physiology; D010147:Pain Measurement / Q000295:instrumentation*; D010812:Physical Stimulation / Q000295:instrumentation*; D012879:Skin Physiological Phenomena; D012984:Software