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Visual and auditory stimuli are relatively easy to present in an MRI environment;
this combined with the fact that vision and audition are the two most widely studied
senses has resulted with a wide array of commercially available devices for these
Purposes-UnfortunatelypresentingtactilestimulusinanMRIenvirOnmentis
considerably more challenging, so before we could study this modality using fMRI we
had to design and build our own device. The design, construction, and performance of
this device is described in the first chapter.
In the second chapter we investigated activation to tactile stimuli in visual area
five (also known as MT for middle temporal). Previous studies have shown activation in
area MT in response to tactile stimuli, however we showed that only a subdivision of
MT, area MST (middle superior temporal) response to tactile stimuli while the rest of
MTdoes not.
In chapter three we describe a human analog to an important multisensory area
present in macaque monkeys called STP (superior temporal polysensory area) which lies
along the fundus of the posterior superior temporal sulcus (STS). Individual neuronsin
this area show activation in response to visual, auditory, and tactile stimuli. Previous
neuroimaging studies have shown multisensory activation to both visual and auditory
stimuli, as well as activation to somatosensory stimuli; however this study is the first to
Showthatresponsestotactilestimuliareco-Iocalizedwithresponsestovisualand
auditory stimuli. This, along with similar anatomical and functional properties
(discussed in the chapter) present strong evidence for identifying this area as a
homologue to STP.