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In chapter four we used multi-pattern voxel analysis (MVPA) to discriminate the
body location of tactile stimuli. We analyzed voxels in primary and secondary
somatosensory cortex, as well as regions of visual association cortex in lateral
occipitotemporal lobe. Previous MVPA studies focused on decoding visual stimuli,
although since visual cortex is the largest and most distributed of the early sensory
cortices it remained unclear whether this technique could be applied to other modalities
with smaller and less distributed representation. We were able to successfully
discriminate the body location of stimulation to a degree much higher than chance,
proving that this technique can be applied to somatosensory stimuli. In addition to
using all areas to train a classifier, we also trained the classifier using SI, Sll and visual
association cortex separately. The results provided a great amount of insight as to the
role of each area in somatosensory processing.
In chapter five we investigated cross-modal interactions between audition and
Somatosensation using psychophysical experiments. Our results indicated that auditory
tones can affect the detection, perceived spatial location, and the perceived frequency
Ofvibrotactilestimuli.
WhilefMRlprovidesapowerfulmethodtofindbrainareasthatincreaseor
decrease activity in response to a stimulus, activity only demonstrates correlation and
not causation (just because a brain area becomes active during a task does not
necessarily mean that that brain area is necessary for the task). One technique that can
prove causality is Transcranial Magnetic Stimulation (TMS), which can noninvasively and
temporarily disable brain areas. One direction of the research that will build on the