Neurocommunications Laboratory, Johns Hopkins University, School of Medicine, Baltimore, Maryland
Studies were made of speech and other motor behavior of a 17-year-old female with severe chronic difficulties in swallowing, chewing, and speaking. Studies included: (a) physical and neurological examination; (b) phonological analysis; (c) electromyography; (d) cinefluorography; (e) non-speech motor tests; (f) tests of phoneme perception, and (g) dichotic auditory perception tests. Neurological examination revealed severe defects in complex somesthetic sensation (e.g. stereognosis). Other sensory functions, including hearing, were normal. Although motor abnormalities of extrapyramidal, cerebellar or peripheral origin were not indicated, the patient was unable to activate the several muscles required for any given speech gesture while at the same time independently controlling their various patterns of activity in normal fashion. It was concluded that this difficulty was not primarily of motor origin but resulted from congenital inability to obtain somesthetic information necessary for learning of the patterns of spatial distribution and temporal modulation of muscle contraction accompanying normal speech. Despite the severe speech production deficits, speech perception approached normality, even in some characteristics which, according to the motor theory of speech perception, are dependent on the listener's referring to the neural correlates of normal speech motor control. Reference to normal motor information does not therefore appear necessary for these types of perceptual performance.