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directly modulating the distance of the auditory information, as well as the intensity
(Occelli, et al. 2008), might be informative regarding some of the boundary conditions of
these enhancing effects on Somatosensation from audition.
It is important to note that our experiments used simultaneous auditory and
tactile stimuli. Therefore, it is unlikely that our results are a consequence of a spatial
orienting of attention effect of the sound on touch, as has been shown in other studies
(cf. Spence and Driver 1997). In contrast to spatial orienting, which requires some time
for attention to move to the locus of an event (Posner 1980), our results could have
been influenced by an increased level of general alerting and/or arousal when an
auditory stimulus was presented. However, the fact that the enhancements of touch
from sound were spatially- and frequency-specific rather than more generally enhancing
suggests that a general alerting or arousal account for these results is insufficient. In
some of our previous work, we have also demonstrated that a simultaneous visual
stimulus can affect tactile processing in similar ways (Johnson, et al. 2006). Taken
together, these findings suggest that these multisensory enhancement effects may be a
result of superadditive processing of vision, audition, and touch in brain areas coding for
all of these sensory modalities (e.g., the superior colliculus and the posterior parietal
cortex). We are currently examining these enhancing effects of sound on touch using
functional magnetic resonance imaging, which may provide further clues to the neural
mechanisms underlying these effects.
Recently, we reported a patient with an interesting linkage between touch and
sound (Ro, et al. 2007). Following a thalamic stroke, the patient had somatosensory