R A Gaunt et al 2009 J. Neural Eng. 6 055009 doi:10.1088/1741-2560/6/5/055009
R A Gaunt1, J A Hokanson2 and D J Weber1,2
Show affiliationsCurrent research in motor neural prosthetics has focused primarily on issues related to the extraction of motor command signals from the brain (e.g. brain–machine interfaces) to direct the motion of prosthetic limbs. Patients using these types of systems could benefit from a somatosensory neural interface that conveys natural tactile and kinesthetic sensations for the prosthesis. Electrical microstimulation within the dorsal root ganglia (DRG) has been proposed as one method to accomplish this, yet little is known about the recruitment properties of electrical microstimulation in activating nerve fibers in this structure. Current-controlled microstimulation pulses in the range of 1–15 µA (200 µs, leading cathodic pulse) were delivered to the L7 DRG in four anesthetized cats using penetrating microelectrode arrays. Evoked responses and their corresponding conduction velocities (CVs) were measured in the sciatic nerve with a 5-pole nerve cuff electrode arranged as two adjacent tripoles. It was found that in 76% of the 69 electrodes tested, the stimulus threshold was less than or equal to 3 µA, with the lowest recorded threshold being 1.1 µA. The CVs of afferents recruited at threshold had a bimodal distribution with peaks at 70 m s−1 and 85 m s−1. In 53% of cases, the CV of the response at threshold was slower (i.e. smaller diameter fiber) than the CVs of responses observed at increasing stimulation amplitudes. In summary, we found that microstimulation applied through penetrating microelectrodes in the DRG provides selective recruitment of afferent fibers from a range of sensory modalities (as identified by CVs) at very low stimulation intensities. We conclude that the DRG may serve as an attractive location from which to introduce surrogate somatosensory feedback into the nervous system.
87.80.-y Biophysical techniques (research methods)
87.19.R- Mechanical and electrical properties of tissues and organs
87.19.lt Sensory systems: visual, auditory, tactile, taste, and olfaction
Issue 5 (October 2009)
Received 19 December 2008, accepted for publication 20 April 2009
Published 1 September 2009
R A Gaunt et al 2009 J. Neural Eng. 6 055009
A. Gáspár et al. 2009 ApJ 697 1578
E Thornton 1960 Proc. Phys. Soc. 76 104
B. Abbott et al. 2007 ApJ 659 918
A E A Warburton and R W Hatfield 1977 J. Phys. A: Math. Gen. 10 909
Alberto L Delis et al 2009 Physiol. Meas. 30 931
Thomas Mussenbrock and Ralf Peter Brinkmann 2007 Plasma Sources Sci. Technol. 16 377
Joseph D Mitchell and Nikola P Petrov 2009 Eur. J. Phys. 30 417
P H Pretorius et al 1998 Phys. Med. Biol. 43 407
Alex Harvey 2009 Eur. J. Phys. 30 877