The name is absent

A third general category of somatosensory fMRI studies use automated
mechanical stimulation. Pneumatic systems have been used effectively (Briggs, et al.
2004; Stippich, et al. 1999), although only at low frequency of stimulation. A hydraulic
system has also been described (Golaszewski, et al. 2002) with a slightly greater range of
stimulation frequency, but still less than 130Hz, and with a minimum displacement of
0.5mm, unsuitable for near-threshold studies. It is also possible to use Lorentz-forces
created by the scanner to generate vibration, although each device will only work at a
fixed distance outside the bore of the scanner (Graham, et al. 2001). Custom-built
motorized devices that are constructed of non-ferrous metal, with the motor placed
well away from the scanner bore, can be used to deliver precise stimuli, such as a
grating or embossed letters to a single body part, typically the finger tip (Burton, et al.
2006; Burton, et al. 2004; Ingeholm, et al. 2006).

Another popular solution is piezoelectric devices (Gizewski, et al. 2005;
Harrington, et al. 2000). Although piezoelectrics have been dismissed as having too little
displacement to provide robust tactile stimulation (Briggs, et al. 2004; Graham, et al.
2001), modern devices are capable of displacements of over a millimeter and have the
advantages of a wide range of possible stimulation frequencies and amplitudes (up to
several mm). Most MR-CompatibIe somatosensory stimulators (piezoelectricor
otherwise) are capable of stimulating only a single body region at a time. Because the
somatosensory system is organized Somatotopically, there are advantages to delivering
stimuli to many body parts in a single experiment. For instance, it allows a more
complete delineation of the extent of somatosensory cortex and raises the possibility of

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