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.
Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099, USA.
W
W
Schneider
R M
RM
Slugg
B P
BP
Turnquist
R A
RA
Meyer
J N
JN
Campbell
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