Effects of stimulus frequency and duration on somatosensory discrimination responses
- 166 Downloads
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.
KeywordsElectrophysiology Evoked potentials Somatosensory Cognition
- Hämäläinen H, Sams M, Pertovaara A, Carlson S, Reinikainen K, Näätänen R (1988) Different functional roles of SI and SII somatosensory cortices as reflected by evoked potentials and multiple-unit responses to mechanical stimulation in awake monkey. Neurosci Res Commun 2:143–150Google Scholar
- Kida T, Nishihira Y, Hatta A, Fumoto M, Wasaka T (2001) Automatic mismatch detection in somatosensory modality and the effect of stimulus probability. Jpn J Clin Neurophysiol 29:417–424Google Scholar
- Näätänen R (1992) Attention and brain function. Lawrence Erlbaum Associates, HillsdaleGoogle Scholar
- Spackman LA, Worely A, Boyd SG (2005) Can normal variations in behaviour change vSERPs? In: IPEM proceedings of the 12th annual scientific meeting, GlasgowGoogle Scholar