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Effects of stimulus frequency and duration on somatosensory discrimination responses

Spackman, Lynne and Boyd, Stewart and Towell, Anthony (2007) Effects of stimulus frequency and duration on somatosensory discrimination responses. Experimental Brain Research, 177 (1). pp. 21-30. ISSN 0014-4819

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Official URL: http://dx.doi.org/10.1007/s00221-006-0650-0

Abstract

Somatosensory processing of duration and frequency changes was investigated using event-related potentials to vibrotactile stimuli. Intermittent vibration to the fingertips of either hand was presented using a two-stimulus odd-ball paradigm (deviant P = 0.10). One group (N = 12, 18–38 years) was presented with stimulus pairs of 20/70, 50/150 and 170/250 ms. A second group (N = 10, 19–34 years) was tested using frequency pairs of 200/70 Hz. A psychophysical study examined the subjects’ ability to discriminate between different stimulus pairs. A clear negative shift in the response to the deviant stimulus was recorded with all the stimulus conditions used in both experiments. Both frequency changes and duration increments/decrements revealed an initial negativity in the subtraction waveform with a mean onset of 90–170 ms and a following positivity, both of which were dependent on the duration of the stimulus used. A significant decrease in the amplitude of both components was observed with the 170/250 ms pairing, coinciding with a positive correlation between individual discrimination performance and amplitude. These results support the existence of a somatosensory mismatch response with features similar to those of the aMMN and highlight the relevance of the somatosensory-specific positivity. Results from the duration experiment also resolve some of the discrepancies between previous studies.

Item Type:Article
Additional Information:Online ISSN 1432-1106
Research Community:University of Westminster > Social Sciences, Humanities and Languages, School of
ID Code:4086
Deposited On:31 May 2007
Last Modified:30 Oct 2009 12:00

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