Functional MRI has already been used in research on processing of acoustic signals in the
inferior colliculi and other nuclei within the brainstem auditory pathway [22-28]. Figure 5
from a study of interaural time processing shows activity in the inferior colliculi, medial
geniculate bodies, and auditory cortex . Figure 6 shows activity in the inferior colliculi
in response to increasing rates of stimuli . Figure 7 shows differences of activity in a
patient with unilateral tinnitus .
Subjects for the research proposed here will include (a) people with traumatic head injury
and damage of the inferior colliculi verified on MRI scans, as in figure 2. Most head
injuries result in greater damage to wide areas of the brain, but if injury of the inferior
colliculi is seen with MRI, decreased activity can be anticipated with fMRI.
If differences between neurologically normal and head injured people are evident in fMRI
responses to verbal and other auditory stimuli, the same stimuli will be used to test function
in (b) adults with presbyacusis, which may involve decline of function in the inferior colliculi
[29-31], (c) adults with lifelong autism, delay in language development, or persisting
language disorders, (d) children with developmental language delay or disorders, and
(e) adults and children (for whom permission can be obtained) with no childhood or current
Recognition of words of two or more syllables presented in quiet (WRIQ) and with
increasing levels of background noise (WRIN) will be used for testing, as described by
Church et al. in research on developmental language problems in children with fetal
alcohol syndrome [32, 33]. Clicks and pure tones presented with increasing repetition
rate, and pure tones delivered out-of-phase at each ear will also be used (especially for
subjects with severe verbal disabilities).