Five-year follow-up of bilateral stimulation of the subthalamic nucleus in advanced Parkinson's disease

Background: Although the short-term benefits of bilateral stimulation of the subthalamic nucleus in patients with advanced Parkinson's disease have been well documented, the long-term outcomes of the procedure are unknown. Methods: We conducted a five-year prospective study of the first 49 consecutive patients whom we treated with bilateral stimulation of the subthalamic nucleus. Patients were assessed at one, three, and five years with levodopa (on medication) and without levodopa (off medication), with use of the Unified Parkinson's Disease Rating Scale. Seven patients did not complete the study: three died, and four were lost to follow-up. Results: As compared with base line, the patients' scores at five years for motor function while off medication improved by 54 percent (P<0.001) and those for activities of daily living improved by 49 percent (P<0.001). Speech was the only motor function for which off-medication scores did not improve. The scores for motor function on medication did not improve one year after surgery, except for the dyskinesia scores. On-medication akinesia, speech, postural stability, and freezing of gait worsened between year 1 and year 5 (P<0.001 for all comparisons). At five years, the dose of dopaminergic treatment and the duration and severity of levodopa-induced dyskinesia were reduced, as compared with base line (P<0.001 for each comparison). The average scores for cognitive performance remained unchanged, but dementia developed in three patients after three years. Mean depression scores remained unchanged. Severe adverse events included a large intracerebral hemorrhage in one patient. One patient committed suicide. Conclusions: Patients with advanced Parkinson's disease who were treated with bilateral stimulation of the subthalamic nucleus had marked improvements over five years in motor function while off medication and in dyskinesia while on medication. There was no control group, but worsening of akinesia, speech, postural stability, freezing of gait, and cognitive function between the first and the fifth year is consistent with the natural history of Parkinson's disease

Inferior frontal oscillations reveal visuo-motor matching for actions and speech: evidence from human intracranial recordings.

The neural correspondence between the systems responsible for the execution and recognition of actions has been suggested both in humans and non-human primates. Apart from being a key region of this visuo-motor observation-execution matching (OEM) system, the human inferior frontal gyrus (IFG) is also important for speech production. The functional overlap of visuo-motor OEM and speech, together with the phylogenetic history of the IFG as a motor area, has led to the idea that speech function has evolved from pre-existing motor systems and to the hypothesis that an OEM system may exist also for speech. However, visuo-motor OEM and speech OEM have never been compared directly. We used electrocorticography to analyze oscillations recorded from intracranial electrodes in human fronto-parieto-temporal cortex during visuo-motor (executing or visually observing an action) and speech OEM tasks (verbally describing an action using the first or third person pronoun). The results show that neural activity related to visuo-motor OEM is widespread in the frontal, parietal, and temporal regions. Speech OEM also elicited widespread responses partly overlapping with visuo-motor OEM sites (bilaterally), including frontal, parietal, and temporal regions. Interestingly a more focal region, the inferior frontal gyrus (bilaterally), showed both visuo-motor OEM and speech OEM properties independent of orolingual speech-unrelated movements. Building on the methodological advantages in human invasive electrocorticography, the present findings provide highly precise spatial and temporal information to support the existence of a modality-independent action representation system in the human brain that is shared between systems for performing, interpreting and describing actions

Logopenic and nonfluent variants of primary progressive aphasia are differentiated by acoustic measures of speech production

Differentiation of logopenic (lvPPA) and nonfluent/agrammatic (nfvPPA) variants of Primary Progressive Aphasia is important yet remains challenging since it hinges on expert based evaluation of speech and language production. In this study acoustic measures of speech in conjunction with voxel-based morphometry were used to determine the success of the measures as an adjunct to diagnosis and to explore the neural basis of apraxia of speech in nfvPPA. Forty-one patients (21 lvPPA, 20 nfvPPA) were recruited from a consecutive sample with suspected frontotemporal dementia. Patients were diagnosed using the current gold-standard of expert perceptual judgment, based on presence/absence of particular speech features during speaking tasks. Seventeen healthy age-matched adults served as controls. MRI scans were available for 11 control and 37 PPA cases; 23 of the PPA cases underwent amyloid ligand PET imaging. Measures, corresponding to perceptual features of apraxia of speech, were periods of silence during reading and relative vowel duration and intensity in polysyllable word repetition. Discriminant function analyses revealed that a measure of relative vowel duration differentiated nfvPPA cases from both control and lvPPA cases (r2 = 0.47) with 88% agreement with expert judgment of presence of apraxia of speech in nfvPPA cases. VBM analysis showed that relative vowel duration covaried with grey matter intensity in areas critical for speech motor planning and programming: precentral gyrus, supplementary motor area and inferior frontal gyrus bilaterally, only affected in the nfvPPA group. This bilateral involvement of frontal speech networks in nfvPPA potentially affects access to compensatory mechanisms involving right hemisphere homologues. Measures of silences during reading also discriminated the PPA and control groups, but did not increase predictive accuracy. Findings suggest that a measure of relative vowel duration from of a polysyllable word repetition task may be sufficient for detecting most cases of apraxia of speech and distinguishing between nfvPPA and lvPPA

THE CHILD AND THE WORLD: How Children acquire Language

HOW CHILDREN ACQUIRE LANGUAGE Over the last few decades research into child language acquisition has been revolutionized by the use of ingenious new techniques which allow one to investigate what in fact infants (that is children not yet able to speak) can perceive when exposed to a stream of speech sound, the discriminations they can make between different speech sounds, differentspeech sound sequences and different words. However on the central features of the mystery, the extraordinarily rapid acquisition of lexicon and complex syntactic structures, little solid progress has been made. The questions being researched are how infants acquire and produce the speech sounds (phonemes) of the community language; how infants find words in the stream of speech; and how they link words to perceived objects or action, that is, discover meanings. In a recent general review in Nature of children's language acquisition, Patricia Kuhl also asked why we do not learn new languages as easily at 50 as at 5 and why computers have not cracked the human linguistic code. The motor theory of language function and origin makes possible a plausible account of child language acquisition generally from which answers can be derived also to these further questions. Why computers so far have been unable to 'crack' the language problem becomes apparent in the light of the motor theory account: computers can have no natural relation between words and their meanings; they have no conceptual store to which the network of words is linked nor do they have the innate aspects of language functioning - represented by function words; computers have no direct links between speech sounds and movement patterns and they do not have the instantly integrated neural patterning underlying thought - they necessarily operate serially and hierarchically. Adults find the acquisition of a new language much more difficult than children do because they are already neurally committed to the link between the words of their first language and the elements in their conceptual store. A second language being acquired by an adult is in direct competition for neural space with the network structures established for the first language

Orofacial cutaneous function in speech motor control and learning

International audienceSomatosensory signals from facial skin can provide a rich source of sensory input. However, it is unknown yet how cutaneous input works on speech motor control and learning. This chapter introduces a kinesthetic role of orofacial cutaneous afferents in speech processing. We argue for specificity of the orofacial somatosensory system from anatomical and physiological perspectives. The contribution of cutaneous afferents to speech production is evident in neurophysiological and psychophysical findings. Somatosensory modulation associated with facial skin deformation induces a reflex for articulatory motion adjustment in speech production and also an adaptive motion change in speech motor learning. In addition, cutaneous mechanoreceptors are narrowly tuned at the skin lateral to the oral angle. An intriguing function of somatosensory inputs associated with facial skin deformation is to interact with the processing of speech perception. Taken together, orofacial cutaneous afferents play an important role in both speech production and perception

On the Assessment of Stability and Patterning of Speech Movements

Speech requires the control of complex movements of orofacial structures to produce dynamic variations in the vocal tract transfer function. The nature of the underlying motor control processes has traditionally been investigated by employing measures of articulatory movements, including movement amplitude, velocity, and duration, at selected points in time. An alternative approach, first used in the study of limb motion, is to examine the entire movement trajectory over time. A new approach to speech movement trajectory analysis was introduced in earlier work from this laboratory. In this method, trajectories from multiple movement sequences are time- and amplitude-normalized, and the STI (spatiotemporal index) is computed to capture the degree of convergence of a set of trajectories onto a single, underlying movement template. This research note describes the rationale for this analysis and provides a detailed description of the signal processing involved. Alternative interpolation procedures for time-normalization of kinematic data are also considered

Comparing Motor Speech Skills of Children with High Functioning Autism versus those of Typically Developing Children using Diadochokinetic Tasks

Undergraduate Research Scholarship for $3000Motor speech function assessments have long been used to help determine diagnoses and treatments for speech-language pathology clients that are suspected of having apraxia, dysarthria, or other frank motor speech disorders. However, motor speech function is rarely assessed in children who may show more subtle motor speech problems, such as speech clients with autism spectrum disorders (ASDs), developmental disorders that primarily affect the development of social and communication skills. The purpose of this study is to look at the particular speech motor task of diadochokinesis (DDK) and determine whether there are group or stimulus type effects on performance. Specifically, (1) are there differences between children with high functioning autism (HFA) and typically developing (TD) children on DDK measurements (rate, accuracy, and consistency)?, and (2) do participant groups differ in their performance on monosyllabic versus multisyllabic stimuli?. To perform this study, two groups (HFA and TD children) were given the DDK task of repeating monosyllabic sounds (/pa/, /ta/, and /ka/) and then multisyllabic sounds (/pataka/) as long and as fast as they could. Mean performances from both groups were compared on the measurements of rate, accuracy, and consistency. The results showed that the HFA group performed generally faster rates across the tasks, but had significantly lower accuracy and consistency scores than the TD group. The findings also showed that, in terms of rate, all participants performed more poorly on the multisyllabic task than the monosyllabic tasks, regardless of group membership. Although the number of participants was small, this study showed promising results in using the DDK task to assess the motor speech skills in children with autism. Further studies are suggested for looking at the importance of rate, accuracy, and consistency in the utterances of HFA children.No embarg

Respiratory, postural and spatio-kinetic motor stabilization, internal models, top-down timed motor coordination and expanded cerebello-cerebral circuitry: a review

Human dexterity, bipedality, and song/speech vocalization in Homo are reviewed within a motor evolution perspective in regard to &#xd;&#xa;&#xd;&#xa;(i) brain expansion in cerebello-cerebral circuitry, &#xd;&#xa;(ii) enhanced predictive internal modeling of body kinematics, body kinetics and action organization, &#xd;&#xa;(iii) motor mastery due to prolonged practice, &#xd;&#xa;(iv) task-determined top-down, and accurately timed feedforward motor adjustment of multiple-body/artifact elements, and &#xd;&#xa;(v) reduction in automatic preflex/spinal reflex mechanisms that would otherwise restrict such top-down processes. &#xd;&#xa;&#xd;&#xa;Dual-task interference and developmental neuroimaging research argues that such internal modeling based motor capabilities are concomitant with the evolution of &#xd;&#xa;(vi) enhanced attentional, executive function and other high-level cognitive processes, and that &#xd;&#xa;(vii) these provide dexterity, bipedality and vocalization with effector nonspecific neural resources. &#xd;&#xa;&#xd;&#xa;The possibility is also raised that such neural resources could &#xd;&#xa;(viii) underlie human internal model based nonmotor cognitions. &#xd;&#xa

Neural correlates of spatial location mapping on the Simon effect

Previous studies show that the effect of practice with incompatible location mapping results in a reverse Simon effect. However, the neural correlates of this phenomenon are yet to be clarified. This study used functional magnetic resonance imaging (fMRI) to explore the neural correlates of the Simon effect after location mapping in 20 healthy young adults who are native English speakers. The results show that incompatible location mapping leads to reduced activation in the premotor, primary motor, supplementary motor area (SMA) and mid-cingulate cortex. As practice with the Simon effect reveals subtle changes in motor function, application of the Simon task in rehabilitation training programs is recommended.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science

The neurological underpinnings of cluttering: Some initial findings

Background Cluttering is a fluency disorder characterised by overly rapid or jerky speech patterns that compromise intelligibility. The neural correlates of cluttering are unknown but theoretical accounts implicate the basal ganglia and medial prefrontal cortex. Dysfunction in these brain areas would be consistent with difficulties in selection and control of speech motor programs that are characteristic of speech disfluencies in cluttering. There is a surprising lack of investigation into this disorder using modern imaging techniques. Here, we used functional MRI to investigate the neural correlates of cluttering. Method We scanned 17 adults who clutter and 17 normally fluent control speakers matched for age and sex. Brain activity was recorded using sparse-sampling functional MRI while participants viewed scenes and either (i) produced overt speech describing the scene or (ii) read out loud a sentence provided that described the scene. Speech was recorded and analysed off line. Differences in brain activity for each condition compared to a silent resting baseline and between conditions were analysed for each group separately (cluster-forming threshold Z > 3.1, extent p 30 voxels, uncorrected). Results In both conditions, the patterns of activation in adults who clutter and control speakers were strikingly similar, particularly at the cortical level. Direct group comparisons revealed greater activity in adults who clutter compared to control speakers in the lateral premotor cortex bilaterally and, as predicted, on the medial surface (pre-supplementary motor area). Subcortically, adults who clutter showed greater activity than control speakers in the basal ganglia. Specifically, the caudate nucleus and putamen were overactive in adults who clutter for the comparison of picture description with sentence reading. In addition, adults who clutter had reduced activity relative to control speakers in the lateral anterior cerebellum bilaterally. Eleven of the 17 adults who clutter also stuttered. This comorbid diagnosis of stuttering was found to contribute to the abnormal overactivity seen in the group of adults who clutter in the right ventral premotor cortex and right anterior cingulate cortex. In the remaining areas of abnormal activity seen in adults who clutter compared to controls, the subgroup who clutter and stutter did not differ from the subgroup who clutter but do not stutter. Conclusions Our findings were in good agreement with theoretical predictions regarding the neural correlates of cluttering. We found evidence for abnormal function in the basal ganglia and their cortical output target, the medial prefrontal cortex. The findings are discussed in relation to models of cluttering that point to problems with motor control of speech