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Abstract:
There is growing evidence from neuropsychology and
neuroimaging that knowledge of living things is localized
separately in the brain from knowledge of nonliving things. Is the
functional distinction between living and nonliving things, and
their segregation in neural tissue, innate, or does experience play
a role in their neural differentiation? If genetically determined,
then perinatal damage to the normal substrates of living things
should result in an enduring category-specific knowledge
impairment. Adam was 14 y.o when tested and had sustained bilateral
posterior cerebral artery strokes at one day of age, resulting in
lesions typical of patients with adult-onset impairments in
knowledge of living things. In Experiment 1, Adam had a significant
impairment in naming drawings of living things, compared to
drawings of nonliving things matched on a variety of factors
determining naming difficulty. In Experiment 2, Adam's visual and
nonvisual semantic knowledge of living and nonliving things was
compared with that of age-matched control subjects, revealing a
category-specific impairment for living things (with no
modality-specificity). In Experiment 3, we found the
living/nonliving distinction so rigidly hardwired that the
acquisition of new verbal knowledge about living things was
selectively impaired, relative to age-matched controls. We conclude
that part of the newborn brain is genetically predetermined to
house knowledge about living things, and when this area is
unavailable, other brain areas cannot acquire this function.
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