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Research Proposal
Speech understanding
Inferior colliculus lesions
Brainstem aphasia?

fMRI of the inferior colliculi
Testing strategies
Anticipated results

Working hypotheses
Language areas on fMRI
Effects of asphyxia at birth
Maturation of the brain
Time-table of myelination
Learning to speak "by ear"
Metabolism in the brain
Protective mechanisms
Catastrophic factors
Brainstem damage
The inferior colliculi appear to be important for speech understanding
Since 1991, with the advent of magnetic resonance imaging (MRI),
eleven cases of deafness and auditory agnosia have been reported,
associated with selective (and bilateral) damage of the inferior colliculi.
Loss of speech understanding ("word deafness") was the primary
problem in nine of these cases [1-10].
The inferior colliculi are metabolically the most active site in the brain
Blood flow and aerobic metabolism are highest in the inferior colliculi [11-15}
The inferior colliculi are vulnerable to any catastrophic disruption of
aerobic metabolism
[16-18, 19-23].
The inferior colliculi are prominently involved in the brainstem pattern of
damage caused by alcohol intoxication, or poisoning by many other toxic
substances, which also can often be catastrophic
[24-29, 30-37].
The inferior colliculi are prominently damaged by a brief period of
oxygen deprivation before, during or after birth
[38-39, 40-49].
Perinatal compromise can cause damage in the inferior colliculi
Impairment of function is likely in infants with prenatal exposure to
alcohol and other drugs
Impairment of function is likely in infants who suffer oxygen deprivation
during a difficult birth and/or develop neonatal jaundice
Impairment of function should be even more serious for infants than adults
who suffer sudden "word deafness" following injury to the inferior colliculi.
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Working version
October 2006
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