We have investigated the central control of laryngeal function for multiple systems including cough, sniff, voice and breathing for speech and voice using functional magnetic resonance imaging. We have used using event related sparse sampling to avoid movement artifact during these activities and scanner noise interference with normal auditory feedback during these activities. We have found widely distributed systems for the control of each of these behaviors that overlap and converge along the Sylvian fissure in the same regions as volitional prolonged exhalation. In addition to the cortical regions for volitional cough that overlap with voluntary breathing control, specific activation occurred in a pontomesencephalic region during voluntary cough. Voluntary sniff to command, a learned respiratory behavior in the human, also involved the same cortical regions in addition to the hippocampus and piriform cortex. The localization of cortical activation for voluntary cough control in humans lays the ground for potential drug development by identifying regions to target in patients with chronic cough. ? ? Convergent with these regions were also those regions for voluntary control of both prolonged exhalation and production of phonatory syllables, which were examined in another study. Contrary to cough and sniff, however, both volitional exhalation and phonation for speech showed greater activation on the left side in the sensori-motor and temporoparietal areas. Significant differences between phonation and exhalation were found primarily in the bilateral auditory cortices with whole-brain analysis. This was initially expected due to the greater intensity of voice feedback occurring during phonatory syllable production. The ROI analysis similarly indicated task differences in the auditory cortex with differences also detected in the infero-lateral motor cortex and dentate nucleus of the cerebellum. A second experiment examined the role of auditory activation during voice production for a phonatory task compared with non-speech vocalization during whimper. Differences between speech-like phonation and whimper tasks occurred; a greater activation was present in the left superior temporal gyrus during phonatory syllables. On the other hand, no differences occurred between phonated and whispered productions of the same syllables demonstrating that the greater activation in the left superior temporal gyrus was not due to differences in the intensity of the auditory feedback. In conclusion, the degree of auditory monitoring was the major difference between phonation for speech and non-speech vocalization or prolonged exhalation. ? ? We are now using both functional and anatomical imaging to examine the brain bases for spasmodic dysphonia, an idiopathic voice disorder that develops spontaneously in mid life. This year, we completed a diffusion tensor imaging study in spasmodic dysphonia patients and found reduced fractional anisotropy in the right internal capsule in comparison with a comparable group of healthy volunteers. A post mortem study of the same region in a patient with spasmodic dysphonia found axonal thinning and calcinosis in the right internal capsule and in the basal ganglia in contrast with brains of older adults without neurological disorders. These are the first findings of neuropathological findings in this idiopathic voice disorder which is considered a focal dystonia affecting the laryngeal motor control for speech.? ? We also examined structural brain correlates of stuttering in childhood. Diffusion tensor imaging was used to examine children who had developmental stuttering in their preschool years and then had either recovered or not recovered when examined later between 9 and 12 years of age using neuroimaging. Both groups had the same white matter deficit in the arcuate fasciculus underlying the rolandic operculum on the left side as was previously reported by others in adults who stutter. This abnormality may place children at risk for stuttering independent of recovery. On the other hand, grey matter volume differences were different from those found previously in stuttering adults. Both the recovered and non-recovered groups had less grey matter volume in the speech regions in both hemispheres. This suggests that the increases in the right hemisphere volume in stuttering adults may be the result of neuroplastic changes induced by speech difficulties and compensatory strategies during a lifetime of stuttering.
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