For subjects who are mute or with severe verbal disabilities, investigation with:
clicks and pure tones presented with increasing repetition rate, from 2/second to
35/second, as in experiments on normal subjects by Harms &Melcher(2002)
pure tones delivered out of phase at each ear, and
presentation of selected multi-syllabic words.
Note: Cardiac gating by the method of Guimaraes et al.
(1998) will be used; the high rate of blood flow in the
brainstem causes pulsations that mask most auditory
stimuli. Quiet MRI as described by Yetkin et al. (2004) will
also be employed. The highest rate of blood flow is to the
inferior colliculi, as was revealed in the experiments on
cerebral circulation by Landau et al. (1955) in radiographic
pictures as shown to the right.
Harms MP, Melcher JR. Sound repetition rate in the human auditory
pathway: representations in the waveshape and amplitude of fMRI
activation. J Neurophysiol. 2002 Sep;88(3):1433-50.
Church MW et al. Hearing, language, speech, vestibular, and
dentofacial disorders in fetal alcohol syndrome. Alcoholism, Clinical
and Experimental Research 1997; 21:227-237.
Guimaraes AR et al. Imaging subcortical auditory activity in humans.
Hum Brain Mapp. 1998;6(1):33-41.
Yetkin FZ et al. Functional magnetic resonance imaging of activation in
subcortical auditory pathway. Laryngoscope. 2004 Jan;114(1):96-101.
Recognition of multi-syllabic words in quiet (WRIQ) and with increasing levels of
background noise (WRIN) would be tested in higher-functioning subjects
following some of the methods of Church et al. (1997) [82-83].
From Kety (1962)on research of
Landau et al. (1955) Trans Am
Neurol Assoc 80:125-9.