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Abstract:
Abstract: It is commonly noted that the left hemisphere is
specialized for language and related cognitive processes, while the
right hemisphere is specialized for visuospatial processes. We are
investigating the idea that specialization of function has an
associated cost. As each hemisphere becomes increasingly
specialized for particular functions, we hypothesize that cortical
regions are co-opted for these burgeoning functions. Since these
co-opted cortical regions were previously performing some other
function, that function will necessarily be adversely affected by
the loss of cortex devoted to it. In our previous research, we
demonstrated that the left hemisphere of a callosotomy patient is
inferior to rats in performing tasks involving visuospatial
judgments. The current study is designed to investigate the
prediction that there are right hemisphere deficits in cognitive
abilities due to the right hemisphere's specialization for
visuospatial functions. The abilities of the right and left
hemispheres of a callosotomy patient are compared to those of
higher primates to determine whether there is any evidence that the
right hemisphere has lost abilities over the course of human
evolution. As predicted, the right hemisphere but not the left
shows specific deficits in cognitive tasks involving comprehension
of quantitative and categorical relations.
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