Electrophysiological evidence of functional integration between the language and motor systems in the brain: a study of the speech Bereitschaftspotential.

OBJECTIVE: We investigated whether the Bereitschaftspotential (BP), an event related potential believed to reflect motor planning, would be modulated by language-related parameters prior to speech. We anticipated that articulatory complexity would produce effects on the BP distribution similar to those demonstrated for complex limb movements. We also hypothesized that lexical semantic operations would independently impact the BP. METHODS: Eighteen participants performed 3 speech tasks designed to differentiate lexical semantic and articulatory contributions to the BP. EEG epochs were time-locked to the earliest source of speech movement per trial. Lip movements were assessed using EMG recordings. Doppler imaging was used to determine the onset of tongue movement during speech, providing a means of identification and elimination of potential artifact. RESULTS: Compared to simple repetition, complex articulations produced an anterior shift in the maximum midline BP. Tasks requiring lexical search and selection augmented these effects and independently elicited a left lateralized asymmetry in the frontal distribution. CONCLUSIONS: The findings indicate that the BP is significantly modulated by linguistic processing, suggesting that the premotor system might play a role in lexical access. SIGNIFICANCE: These novel findings support the notion that the motor systems may play a significant role in the formulation of language.

Functional neuroanatomy of human vocalization: an H215O PET study.

Vocalization in lower animals is associated with a well-described visceromotor call system centered on the mesencephalic periacqueductal grey matter (PAG), which is itself regulated by paramedian cortical structures. To determine the role this phylogenetically older system plays in human phonation, we contrasted voiced and unvoiced speech using positron emission tomography and then evaluated functional connectivity of regions that significantly differentiated these conditions. Vocalization was associated with increased and highly correlated activity within the midline structures--PAG and paramedian cortices--described in lower mammalian species. Concurrent activation and connectivity of neocortical and subcortical motor regions--medial and lateral premotor structures and elements of basal ganglia thalamocortical circuitry--suggest a mechanism by which this system may have come under an increasing degree of voluntary control in humans. Additionally, areas in the temporal lobe and cerebellum were selectively activated during voiced but not unvoiced speech. These regions are functionally coupled to both visceromotor and neocortical motor areas during production of voiced speech, suggesting they may play a central role in self-monitoring and feedback regulation of human phonation.

Gene expression analysis of the catalytic subunit of human telomerase (hEST2) in the differential diagnosis of serous effusions.

Diagnostic accuracy in effusion cytology based on morphologic examination is not always satisfactory. Therefore, various diagnostic adjuncts such as immunocytochemistry or deoxyribonucleic acid cytometry are employed in this diagnostic field. Recently, demonstration of telomerase activity has been proposed as a possible marker for malignancy. In this study a seminested reverse transcription-polymerase chain reaction (RT-PCR) strategy for expression analysis of the catalytic subunit of human telomerase (hEST2) was used in 58 serous effusions. RT-PCR results correlated with cytologic diagnoses in 14 of 17 malignant effusions. In eight effusions cytologically suspicious for malignancy, PCR results were in accordance with the clinical follow-up. However, hEST2 RT-PCR was also positive in six of 15 cytologically benign effusions that consisted predominantly of inflammatory and mesothelial cells. Using the telomeric repeat amplification protocol, it could be demonstrated that cultured, proliferating benign mesothelial cells may present a weak telomerase activity, as is known in other benign cells including activated lymphocytes. In conclusion, the simple and rapid method of hEST2 RT-PCR serves to support the cytologic diagnosis of malignancy, but false-positive PCR results resulting from activated lymphocytes and proliferating mesothelial cells must be considered.

Changes in vocal intensity in Parkinson's disease following pallidotomy surgery.

The present study was designed to examine changes in vocal intensity following unilateral posteroventral pallidotomy (PVP) in a large sample of speakers with Parkinson's disease (PD) that exhibited a range of hypokinetic dysarthria. Twenty-five persons with PD were recorded using a variety of speech tasks, once prior to and once following PVP. The pre-PVP vocal SPL was subtracted from the post-PVP vocal SPL to derive a relative change in vocal SPL. Mildly dysarthric participants had significantly greater relative increases in vocal SPL following PVP than either moderately or severely dysarthric participants who had reduced vocal SPL following PVP. If future results follow those observed in the present data, mildly dysarthric Parkinson's patients may benefit most from unilateral PVP perhaps due to less overall destruction of the basal ganglia sensorimotor control circuits involved in oral facial functions, thus increasing the chances to observe improvements postsurgery.

Effects of speech therapy and pharmacologic and surgical treatments on voice and speech in Parkinson's disease: a review of the literature.

The purpose of this review was to examine the different treatment approaches for persons with Parkinson's Disease (PD) and to examine the effects of these treatments on speech. Treatment methods reviewed include speech therapy, pharmacological, and surgical. Research from the 1950s through the 1970s had not demonstrated significant improvements following speech therapy. Recent research has shown that speech therapy (when persons with PD are optimally medicated) has proven to be the most efficacious therapeutic method for improving voice and speech function. Pharmacological methods of treatment in isolation do not appear to significantly improve voice and speech function in PD across research studies. Surgical treatment methods including pallidotomy and deep brain stimulation may be significant treatment options which improve voice and speech function in some persons with PD. Possible explanations for the differential responses to treatment are discussed. Future studies should investigate the effects of combined treatment approaches. Perhaps the combination of pharmacological, surgical and speech treatment will prove superior to treatments combining pharmacological and surgical or pharmacological and speech therapy in improving the communication abilities of persons with PD.

Speech and oral motor learning in individuals with cerebellar atrophy.

The purpose of this study was to determine whether cerebellar pathology interferes with motor learning for either speech or novel tasks. Practice effects were contrasted between persons with cerebellar cortical atrophy (CCA) and control participants on previously learned real speech, nonsense speech, and novel nonspeech oral-movement tasks. Studies of limb motor learning suggested that control participants would evidence reduced variability, increased speed of movement, and reduced movement amplitude with practice as compared with the CCA group. No significant differences were found between the real- and nonsense-speech tasks. For both speech tasks, although neither group reduced their movement variability with practice, both groups significantly reduced jaw closing displacement and velocity with practice. For the novel nonspeech oral-movement task, no change with practice was observed in either group in terms of variability, amplitude, or peak velocity. No effects of cerebellar pathology were seen in either the speech- or oral-movement tasks. These results demonstrated that with practice of speech tasks, a previously learned motor skill, movement speed and displacement decreased in both groups. Therefore, the effects of practice differed between previously learned speech tasks and the novel oral-movement task regardless of cerebellar pathology.

Voice and speech characteristics of persons with Parkinson's disease pre- and post-pallidotomy surgery: preliminary findings.

Pallidotomy surgery, lesioning the globus pallidus internal, has been performed to alleviate Parkinsonian symptoms and drug-induced dyskinesias. Improvements in limb motor function have been reported in recent years following pallidotomy surgery. The purpose of this preliminary study was to determine the effect of pallidotomy surgery on select voice and speech characteristics of 6 patients with Parkinson's disease. Acoustic measures were analyzed pre-pallidotomy surgery and again at 3 months following surgery. Preliminary findings indicated that all participants demonstrated positive changes in at least one acoustic measure; 2 of the participants consistently demonstrated positive changes in phonatory and articulatory measures, whereas 3 participants did not consistently demonstrate positive changes postsurgery. The results are discussed relative to the differential effects observed across participants.

Speech production impairments following left and right hemisphere stroke.

A speech production impairment can occur following damage to either the left or right hemisphere. The nature of the impairment, however, differs depending on which hemisphere is damaged and within the left hemisphere, whether the damage is to the anterior or posterior language areas. This paper reviews the recent literature on the types of speech production impairments that follow damage to the left and right cerebral hemispheres. Damage to the left hemisphere anterior language area causes primarily a phonetic impairment, i.e. a deficit in executing the articulatory maneuvers of sound production with a preserved ability to select the correct sound. Damage to the left hemisphere posterior language area causes primarily a phonological impairment, i.e. a deficit in the correct selection of a sound with an intact ability to implement the articulatory maneuvers for that incorrect sound. Damage to the right hemisphere can cause a speech production problem to the prosodic aspects of language. These differences have direct implications for the theraputic remediation of these speech production impairments.

Abnormalities in long latency responses to superior laryngeal nerve stimulation in adductor spasmodic dysphonia.

Sensorimotor responses to repeated electrical stimulation of the superior laryngeal nerve were compared in 8 patients with adductor spasmodic dysphonia (ADSD) and 11 normal controls to determine if adductor response disinhibition occurred in ADSD. Pairs of electrical pulses were presented at interstimulus intervals varying from 100 to 5,000 milliseconds (ms). Three responses were measured in thyroarytenoid muscles: ipsilateral R1 responses at 17 ms and ipsilateral and contralateral R2 responses between 60 and 75 ms. Conditioned response characteristics, the percent occurrence and percentage amplitude of initial responses, were measures of response inhibition. As a group, the patients had reduced response inhibition: their conditioned ipsilateral R1 response amplitudes were increased, as was the frequency of their conditioned contralateral muscle responses (p < or = .002) compared to normal. However, the patients' initial responses were normal in latency and frequency characteristics, demonstrating that the brain stem mechanisms for these responses were intact. These results suggest a central disinhibition of laryngeal responses to sensory input in ADSD.

Stop consonant production in isolated and repeated syllables in Parkinson's disease.

To determine if Parkinson's disease (PD) patients have increasing difficulty as speech tasks become longer or more complex, the timing and accuracy of isolated syllables and repeated sequences of syllables were studied. Acoustic measures of PD patient's syllables were similarly impaired relative to normal controls for both isolated and repeated syllable sequences. Listeners' identification scores were equally high for both types of productions. Unlike previous studies of other types of movements in PD, speech accuracy and timing does not deteriorate as items become longer or more complex.

Effects of botulinum toxin injections on speech in adductor spasmodic dysphonia.

Adductor spasmodic dysphonia involves an overadduction of the vocal folds during speech causing uncontrolled voice and pitch breaks and slow, effortful speech. The disorder is resistant to speech therapy and often recurs following initial benefit from unilateral recurrent laryngeal nerve resection. Botulinum toxin injections into multiple sites of the thyroarytenoid muscle on one side were performed in 16 patients. Speech was recorded prior to injection and three times post-injection. Symptoms were measured by two examiners from speech spectrograms without knowledge of speaker identity or recording session. Significant (p less than or equal to 0.03) reductions in pitch and voice breaks, phonatory aperiodicity, and sentence time occurred only when injections resulted in unilateral vocal fold paralysis. Symptoms returned with the restoration of vocal fold movement, 3 months later. Reduction in speed of swallowing without aspiration was reported in 80% of cases. Although speech volume was reduced, there were no instances of aphonia.