title: Electrotactile stimulation on the tongue: Intensity perception, discrimination, and cross-modality estimation.
abstract: Due to its high sensitivity and conductivity, electrotactile stimulation (ETS) on the tongue has proven to be a useful and technically convenient tool to substitute and/or augment sensory capabilities. However, most of its applications have only provided spatial attributes and little is known about (a) the ability of the tongue's sensory system to process electrical stimuli of varying magnitudes and (b) how modulation of ETS intensity affects subjects' ability to decode stimulus intensity. We addressed these questions by quantifying: (1) the magnitude of the dynamic range (DR; maximal comfortable intensity/perception threshold) and its sensitivity to prolonged exposure; (2) subjects' ability to perceive intensity changes; and (3) subjects' ability to associate intensity with angular excursions of a protractor's handle. We found that the average DR (17 dB) was generally large in comparison with other tactile loci and of a relatively constant magnitude among subjects, even after prolonged exposure, despite a slight but significant upward drift (p < 0.001). Additionally, our results showed that as stimulus intensity increased, subjects' ability to discriminate ETS stimuli of different intensities improved (p < 0.05) while estimation accuracy, in general, slightly decreased (increasing underestimation). These results suggest that higher ETS intensity may increase recruitment of rapidly adapting mechanoreceptor fibers, as these are specialized for coding stimulus differences rather than absolute intensities. Furthermore, our study revealed that the tongue's sensory system can effectively convey electrical stimuli despite minimal practice and when information transfer is limited by memory and DR drift.
authors.affiliation: Department of Kinesiology, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Cecil A
authors.initials: CA
authors.lastname: Lozano
authors.forename: Kurt A
authors.initials: KA
authors.lastname: Kaczmarek
authors.forename: Marco
authors.initials: M
authors.lastname: Santello
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D012684:Sensory Thresholds / Q000502:physiology*; D014059:Tongue / Q000294:innervation* / Q000502:physiology*; D014110:Touch
references.citation: IEEE Trans Neural Syst Rehabil Eng. 2008 Aug;16(4):410-5
references.pmid: 18713678
references.citation: Med Biol Eng Comput. 1977 Jul;15(4):363-73
references.pmid: 197328
references.citation: Somatosens Mot Res. 2007 Dec;24(4):179-88
references.pmid: 18097991
references.citation: Am J Otolaryngol. 1989 Sep-Oct;10(5):342-4
references.pmid: 2817250
references.citation: IEEE Trans Rehabil Eng. 2000 Dec;8(4):499-505
references.pmid: 11204041
references.citation: J Acoust Soc Am. 2004 Oct;116(4 Pt 1):2258-68
references.pmid: 15532657
references.citation: Am J Psychol. 1971 Dec;84(4):487-99
references.pmid: 5142061
references.citation: J Acoust Soc Am. 1969 Aug;46(2):372-83
references.pmid: 5804107
references.citation: Am J Psychol. 2004 Winter;117(4):543-64
references.pmid: 15605958
references.citation: J Vestib Res. 2007;17(2-3):119-30
references.pmid: 18413905
references.citation: Trends Cogn Sci. 2003 Dec;7(12):541-6
references.pmid: 14643370
references.citation: Percept Psychophys. 1981 Dec;30(6):579-86
references.pmid: 7335455
references.citation: Neurosci Lett. 2008 Feb 6;431(3):206-10
references.pmid: 18166270
references.citation: J Speech Hear Res. 1970 Sep;13(3):635-44
references.pmid: 5507119
references.citation: IEEE Trans Rehabil Eng. 2000 Jun;8(2):268-70
references.pmid: 10896199
references.citation: J Acoust Soc Am. 1983 Apr;73(4):1283-92
references.pmid: 6687893
references.citation: IEEE Trans Neural Syst Rehabil Eng. 2006 Mar;14(1):116-23
references.pmid: 16562639
references.citation: IEEE Trans Biomed Eng. 1991 Jul;38(7):679-86
references.pmid: 1879861
references.citation: J Neurosurg. 1983 Nov;59(5):781-9
references.pmid: 6604794
references.citation: Ann Biomed Eng. 1986;14(4):369-81
references.pmid: 3752640
references.citation: IEEE Trans Biomed Eng. 1991 Jan;38(1):1-16
references.pmid: 2026426
references.citation: J Clin Neurophysiol. 2000 Nov;17(6):539-58
references.pmid: 11151974
references.citation: IEEE Trans Neural Syst Rehabil Eng. 2003 Mar;11(1):9-16
references.pmid: 12797720
references.citation: J Neurophysiol. 1997 Feb;77(2):737-48
references.pmid: 9065846
references.citation: J Physiol. 1979 Jan;286:283-300
references.pmid: 439026
references.citation: Physiol Behav. 2003 Nov;80(2-3):289-302
references.pmid: 14637228
references.citation: Brain. 2005 Mar;128(Pt 3):606-14
references.pmid: 15634727
references.citation: IEEE Trans Biomed Eng. 1984 Aug;31(8):558-60
references.pmid: 6490033
references.citation: Science. 1978 Apr 21;200(4339):330-2
references.pmid: 635592
references.citation: J Integr Neurosci. 2003 Dec;2(2):159-64
references.pmid: 15011268
references.citation: J Rehabil Res Dev. 2005 Sep-Oct;42(5):705-14
references.pmid: 16586196
references.citation: Scand J Psychol. 1967;8(2):65-76
references.pmid: 6043518
references.citation: Optom Vis Sci. 2001 Jan;78(1):56-64
references.pmid: 11233336
references.citation: Neurology. 1994 Dec;44(12):2361-6
references.pmid: 7991127
references.citation: J Rehabil Res Dev. 1998 Oct;35(4):427-30
references.pmid: 10220221
references.citation: J Acoust Soc Am. 1996 Oct;100(4 Pt 1):2393-414
references.pmid: 8865646
references.citation: IEEE Trans Biomed Eng. 1992 Jul;39(7):701-15
references.pmid: 1516937