Tactile input plays a key role in visualization, study finds
THURSDAY, May 28 (HealthDay News) -- Touch alone can activate areas of the brain triggered when people look at objects, a finding that shows that these regions process information about objects using different types of sensory input, according to a new study.
Researchers at the University of Birmingham in the United Kingdom studied a man who suffered stroke-related damage in an area of the brain called the lateral occipital cortex (LO), which plays an important role in object recognition. As a result, the man couldn't process visual input normally; he could see objects, but they were jumbled figures to him a condition called visual agnosia.
However, the man could still recognize objects by holding them.
The researchers used functional MRI to compare brain activity in the mans brain and in healthy volunteers while they looked at pictures of objects and scrambled images and touched objects with one hand.
The results showed that tactile input is not secondary to visual recognition in activation of dorsal LO. Rather, it can operate directly through sense of touch, the study found.
"Our data indicate, for the first time, that at least some regions in the LO can be activated normally from touch, even when input from ventral LO is lesioned and visual recognition is prevented," the researchers wrote. "This is consistent with estimates of effective connectivity from functional MRI that have implied that there are direct connections between somatosensory cortex and LO."
The study appears online May 28 in the journal Current Biology.
The U.S. National Institute of Neurological Disorders and Stroke has more about agnosia.
-- Robert Preidt
SOURCE: Cell Press, news release, May 28, 2009
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