Motor Speech Area Research Articles

Brain activity related to phonation in young patients with adductor spasmodic dysphonia

This study investigated the brain activities during phonation of young patients with adductor spasmodic dysphonia (ADSD) of relatively short disease duration (<10 years). Six subjects with ADSD of short duration (mean age: 24. 3 years; mean disease duration: 41 months) and six healthy controls (mean age: 30.8 years) underwent functional magnetic resonance imaging (fMRI) using a sparse sampling method to identify brain activity during vowel phonation (/i:/). Intragroup and intergroup analyses were performed using statistical parametric mapping software. Areas of activation in the ADSD and control groups were similar to those reported previously for vowel phonation. All of the activated areas were observed bilaterally and symmetrically. Intergroup analysis revealed higher brain activities in the SD group in the auditory-related areas (Brodmann's areas [BA] 40, 41), motor speech areas (BA44, 45), bilateral insula (BA13), bilateral cerebellum, and middle frontal gyrus (BA46). Areas with lower activation were in the left primary sensory area (BA1-3) and bilateral subcortical nucleus (putamen and globus pallidus). The auditory cortical responses observed may reflect that young ADSD patients control their voice by use of the motor speech area, insula, inferior parietal cortex, and cerebellum. Neural activity in the primary sensory area and basal ganglia may affect the voice symptoms of young ADSD patients with short disease duration.

The Selective Role of Premotor Cortex in Speech Perception: A Contribution to Phoneme Judgements but not Speech Comprehension

Several accounts of speech perception propose that the areas involved in producing language are also involved in perceiving it. In line with this view, neuroimaging studies show activation of premotor cortex (PMC) during phoneme judgment tasks; however, there is debate about whether speech perception necessarily involves motor processes, across all task contexts, or whether the contribution of PMC is restricted to tasks requiring explicit phoneme awareness. Some aspects of speech processing, such as mapping sounds onto meaning, may proceed without the involvement of motor speech areas if PMC specifically contributes to the manipulation and categorical perception of phonemes. We applied TMS to three sites-PMC, posterior superior temporal gyrus, and occipital pole-and for the first time within the TMS literature, directly contrasted two speech perception tasks that required explicit phoneme decisions and mapping of speech sounds onto semantic categories, respectively. TMS to PMC disrupted explicit phonological judgments but not access to meaning for the same speech stimuli. TMS to two further sites confirmed that this pattern was site specific and did not reflect a generic difference in the susceptibility of our experimental tasks to TMS: stimulation of pSTG, a site involved in auditory processing, disrupted performance in both language tasks, whereas stimulation of occipital pole had no effect on performance in either task. These findings demonstrate that, although PMC is important for explicit phonological judgments, crucially, PMC is not necessary for mapping speech onto meanings.

Effective cerebral connectivity during silent speech reading revealed by functional magnetic resonance imaging.

Seeing the articulatory gestures of the speaker (“speech reading”) enhances speech perception especially in noisy conditions. Recent neuroimaging studies tentatively suggest that speech reading activates speech motor system, which then influences superior-posterior temporal lobe auditory areas via an efference copy. Here, nineteen healthy volunteers were presented with silent videoclips of a person articulating Finnish vowels /a/, /i/ (non-targets), and /o/ (targets) during event-related functional magnetic resonance imaging (fMRI). Speech reading significantly activated visual cortex, posterior fusiform gyrus (pFG), posterior superior temporal gyrus and sulcus (pSTG/S), and the speech motor areas, including premotor cortex, parts of the inferior (IFG) and middle (MFG) frontal gyri extending into frontal polar (FP) structures, somatosensory areas, and supramarginal gyrus (SMG). Structural equation modelling (SEM) of these data suggested that information flows first from extrastriate visual cortex to pFS, and from there, in parallel, to pSTG/S and MFG/FP. From pSTG/S information flow continues to IFG or SMG and eventually somatosensory areas. Feedback connectivity was estimated to run from MFG/FP to IFG, and pSTG/S. The direct functional connection from pFG to MFG/FP and feedback connection from MFG/FP to pSTG/S and IFG support the hypothesis of prefrontal speech motor areas influencing auditory speech processing in pSTG/S via an efference copy.

PTERION: A SITE FOR NEUROSURGICAL APPROACH

Pterion is defined as point of sutural confluence seen in the normal ateralis of the skull where frontal, parietal, temporal and sphenoid bones meet. It is a commonly used neurosurgical landmark. The anatomic location of the pterion is important in surgical interventions following surgical approaches to the anterior and middle cranial fossae, following extradural hemorrhage as well as tumors involving inferior aspects of the frontal lobe, such as olfactory meningioma, used in operations on the Broca's motor speech area and in repairing aneurysms of the middle cerebral artery as well as those of the upper basilar complex and also the anatomical varieties of the pterion, is of interest mainly to anthropologists and forensic pathologists, for assessing the location of the pterion in incomplete archeological remains or forensic materials. The pterion exhibits population-based variations. The aim of the study is to determine the position of the pterion using the midpoint of the zygoma (MPZ) and the frontozygomatic suture (FZS) as palpable points.In the present study seventy dry skulls (34 male and 36 female) were used. The dry skulls were obtained from the department of anatomy, K M C Mangalore, Manipal University. Only the intact skulls were included in the study. The sexing was done on the morphological basis. The Distance between pterion to FZS and pterion to MPZ of right and left side of the male skull bones when compared with the right and left side of female skull bones showed statistically significant side difference among male and female bones.

Are There Excitability Changes in the Hand Motor Cortex During Speech in Left-Handed Subjects?

Hemispheric dominance was investigated in left-handed subjects using single transcranial magnetic stimulation to assess the possible effect of forced change in the dominant hand. Single transcranial magnetic stimuli were delivered randomly over the hand area of the left or right motor cortex of 8 Japanese self-declared left-handed adult volunteers. Electromyographic responses were recorded in the relaxed first dorsal interosseous muscle while the subjects read aloud. Laterality quotient calculated by the Edinburgh Inventory ranged from -100 to -5.26 and laterality index calculated from motor evoked potentials ranged from -86.2 to 38.8. There was no significant correlation between laterality quotient and laterality index. Mean data values across all 8 subjects indicated significant increases only in the left hand. Our ratio analysis of facilitation of the hand motor potentials showed that 2 each of the 8 self-declared left-handers were right- and left-hand dominant and the other 4 were bilateral-hand dominant. Speech dominancy was localized primarily in the right cerebral hemisphere in left-handed subjects, but some individuals exhibited bilateral or left dominance, possibly attributable to the forced change of hand preference for writing in childhood. Our findings suggest changes in the connections between the speech and hand motor areas.

Examining the McGurk illusion using high-field 7 Tesla functional MRI

In natural communication speech perception is profoundly influenced by observable mouth movements. The additional visual information can greatly facilitate intelligibility but incongruent visual information may also lead to novel percepts that neither match the auditory nor the visual information as evidenced by the McGurk effect. Recent models of audiovisual (AV) speech perception accentuate the role of speech motor areas and the integrative brain sites in the vicinity of the superior temporal sulcus (STS) for speech perception. In this event-related 7 Tesla fMRI study we used three naturally spoken syllable pairs with matching AV information and one syllable pair designed to elicit the McGurk illusion. The data analysis focused on brain sites involved in processing and fusing of AV speech and engaged in the analysis of auditory and visual differences within AV presented speech. Successful fusion of AV speech is related to activity within the STS of both hemispheres. Our data supports and extends the audio-visual-motor model of speech perception by dissociating areas involved in perceptual fusion from areas more generally related to the processing of AV incongruence.

The effects of anaesthetic agents on cortical mapping during neurosurgical procedures involving eloquent areas of the brain

In patients presenting for surgical resection of lesions involving, or adjacent to, the functionally important eloquent cortical areas, it is vital to achieve complete or near complete resection of the pathology without damaging the healthy surrounding tissues.The eloquent areas that the surgeons are concerned with are the primary motor, premotor cortex, supplementary motor cortex and speech areas. If the lesions are within these regions surgeons could either take a biopsy or do a intracapsular decompression without damaging the mentioned areas to avoid postoperative dysfunction. If the lesions are adjacent to the above mentioned areas, the normal anatomy would get distorted. However, proper identification of the above mentioned areas would enable the surgeon to radically remove the tumours. Intraoperative mapping of the cortex with stimulating and recording electrodes is termed as electrophysiological (EP) mapping.The EP mapping of motor, sensory and language cortex is widely employed in the resection of lesions involving or adjacent to the eloquent areas. Both intravenous and inhalational agents are known to affect these EP mapping techniques. The aim of this review was to evaluate the effect of anaesthetic agents on intra-operative EP mapping in patients undergoing neurosurgical procedures involving, or adjacent to, the functional areas of the cortex under general anaesthesia. We searched the Cochrane Epilepsy Group Specialized Register (7 March 2011), The Cochrane Central Register of Controlled Trials (CENTRAL issue 1 of 4, The Cochrane Library 2011), MEDLINE (Ovid, 1948 to February week 4, 2011), PsycINFO (EBSCOhost, 7 March 2011), and the National Research Register Archive and UK Clinical Research Network (7 March 2011). We also contacted other researchers in the field in an attempt to ascertain unpublished studies. We planned to include randomised and quasi randomised controlled trials irrespective of blinding in patients of any age or gender undergoing neurosurgery under general anaesthesia where cortical mapping was attempted to identify eloquent areas using either somatosensory evoked potentials (SSEPs), or direct cortical stimulation (DCS) triggered muscle motor evoked potentials (mMEPs), or both. We excluded patients from trials where the anaesthetic effects were evaluated during spinal cord surgery or where MEPs were recorded from modes other than direct cortical stimulation such as transcranial electrical stimulation (TcMEPs), MEPs derived from epidural electrodes (D waves) and magnetic stimulation and trials involving awake craniotomies or the asleep-awake-asleep technique during cortical mapping. Two review authors planned to independently apply the inclusion criteria and extract data. No RCTs were found for this study population. This review highlights the need for well-designed randomised controlled trials to assess the effect of anaesthetic agents on cortical mapping during neurosurgical procedures involving eloquent areas of the brain.

A venous malformation accompanying focal cortical dysplasia resulting in a reorganization of language-eloquent areas

Language functions are likely to become reorganized in patients with a congenital anomaly in the left hemisphere, especially if the lesion affects the classical Broca’s or Wernicke’s language areas. We describe a patient who presented with a venous malformation accompanying focal cortical dysplasias in the left frontal region. The epileptogenic zone (EZ) was localized in Broca’s area, and the motor speech area was identified in the ipsilateral posterior part of the superior temporal gyrus by electrocortical stimulation. We completely resected the EZ in Broca’s area. The patient was seizure-free with no post-surgical neurological deficits at last follow-up. The result of this study may help to extend the use of epilepsy surgery within eloquent areas, and also partly explain the plasticity and reshaping of the language processing functional areas associated with a congenital lesion and chronic epilepsy.

Neural correlates of efficacy of voice therapy in Parkinson's disease identified by performance–correlation analysis

LSVT LOUD (Lee Silverman Voice Treatment) is efficacious in the treatment of speech disorders in idiopathic Parkinson's disease (IPD), particularly hypophonia. Functional imaging in patients with IPD has shown abnormalities in several speech regions and changes in these areas immediately following treatment. This study serves to extend the analysis by correlating changes of regional neural activity with the main behavioral change following treatment, namely, increased vocal intensity. Ten IPD participants with hypophonia were studied before and after LSVT LOUD. Cerebral blood flow during rest and reading conditions were measured by H(2)(15)O-positron emission tomography. Z-score images were generated by contrasting reading with rest conditions for pre- and post-LSVT LOUD sessions. Neuronal activity during reading in the pre- versus post-LSVT LOUD contrast was correlated with corresponding change in vocal intensity to generate correlation images. Behaviorally, vocal intensity for speech tasks increased significantly after LSVT LOUD. The contrast and correlation analyses indicate a treatment-dependent shift to the right hemisphere with modification in the speech motor regions as well as in prefrontal and temporal areas. We interpret the modification of activity in these regions to be a top-down effect of LSVT LOUD. The absence of an effect of LSVT LOUD on the basal ganglion supports this argument. Our findings indicate that the therapeutic effect of LSVT LOUD in IPD hypophonia results from a shift in cortical activity to the right hemisphere. These findings demonstrate that the short-term changes in the speech motor and multimodal integration areas can occur in a top-down manner.

Activation of the Left Inferior Frontal Gyrus in the First 200 ms of Reading: Evidence from Magnetoencephalography (MEG)

BackgroundIt is well established that the left inferior frontal gyrus plays a key role in the cerebral cortical network that supports reading and visual word recognition. Less clear is when in time this contribution begins. We used magnetoencephalography (MEG), which has both good spatial and excellent temporal resolution, to address this question.Methodology/Principal FindingsMEG data were recorded during a passive viewing paradigm, chosen to emphasize the stimulus-driven component of the cortical response, in which right-handed participants were presented words, consonant strings, and unfamiliar faces to central vision. Time-frequency analyses showed a left-lateralized inferior frontal gyrus (pars opercularis) response to words between 100–250 ms in the beta frequency band that was significantly stronger than the response to consonant strings or faces. The left inferior frontal gyrus response to words peaked at ∼130 ms. This response was significantly later in time than the left middle occipital gyrus, which peaked at ∼115 ms, but not significantly different from the peak response in the left mid fusiform gyrus, which peaked at ∼140 ms, at a location coincident with the fMRI–defined visual word form area (VWFA). Significant responses were also detected to words in other parts of the reading network, including the anterior middle temporal gyrus, the left posterior middle temporal gyrus, the angular and supramarginal gyri, and the left superior temporal gyrus.Conclusions/SignificanceThese findings suggest very early interactions between the vision and language domains during visual word recognition, with speech motor areas being activated at the same time as the orthographic word-form is being resolved within the fusiform gyrus. This challenges the conventional view of a temporally serial processing sequence for visual word recognition in which letter forms are initially decoded, interact with their phonological and semantic representations, and only then gain access to a speech code.

Handedness: dependent asymmetrical location of the human primary gustatory area, area G

In magnetoencephalogram studies, the primary gustatory area, area G, is not always seen in the same coronal plane in both hemispheres. We investigated possible asymmetry in right-handed and left-handed individuals by functional MRI. Group analyses revealed a significant difference in the antero-posterior coordinates of the area G between the right and left hemispheres in the right-handed group, but not in the left-handed group, indicating significant morphometric asymmetry in the former group and ambiguous morphometric asymmetry in the latter. However, in left-handed individuals with motor speech areas detected in the right hemisphere, area G was more posteriorly located in the right than in the left hemisphere. These findings suggest that the motor speech area contributes to the asymmetric location of area G.

Persistent dysarthria after cefazolin-induced status epilepticus

Background: Cefazolin is a well-known antibiotic associated with seizures. However, intrathecal cefazolin-induced status epilepticus (SE) is very rare and resultant persistent dysarthria has not been previously reported.Case report: A 66-year-old woman underwent epidural adhesiolysis due to lumbar spinal stenosis and 500 mg of cefazolin was infused through the thecal puncture site during the procedure. SE developed abruptly 40 minutes later and it persisted for 3 days. Severe dysarthria, dysphagia and cognitive dysfunction developed after the cessation of SE. Although the patient's other symptoms showed much improvement after rehabilitation, the dysarthria did not improve after intense speech therapy for 8 months. The brain MRI showed no abnormal findings, but the 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) of the brain demonstrated hypometabolic areas in the bilateral inferior frontal gyrus and the primary motor cortex, representing the oromotor area.Conclusion: Although the exact mechanism underlying the dysarthria is unknown, the dysfunction of the inferior frontal network for speech production revealed by the brain FDG-PET, including the motor speech area (Broca's area), left insula and bilateral primary and premotor cortex representing the oromotor area, might have been responsible for the persistent dysarthria in this patient.

Walking the talk—Speech activates the leg motor cortex

Speech may have evolved from earlier modes of communication based on gestures. Consistent with such a motor theory of speech, cortical orofacial and hand motor areas are activated by both speech production and speech perception. However, the extent of speech-related activation of the motor cortex remains unclear. Therefore, we examined if reading and listening to continuous prose also activates non-brachiofacial motor representations like the leg motor cortex. We found corticospinal excitability of bilateral leg muscle representations to be enhanced by speech production and silent reading. Control experiments showed that speech production yielded stronger facilitation of the leg motor system than non-verbal tongue–mouth mobilization and silent reading more than a visuo-attentional task thus indicating speech-specificity of the effect. In the frame of the motor theory of speech this finding suggests that the system of gestural communication, from which speech may have evolved, is not confined to the hand but includes gestural movements of other body parts as well.

Neural correlates of speech and non-speech processing: Role of language experience in brain activation

In adults, neural responses to the acoustic properties of native and non-native speech sounds differ. Recent magnetoencephalography (MEG) studies indicate that two regions of the brain, the superior temporal area and inferior parietal area (Broca's), in both the left and right hemispheres, may contribute to how the adult brain responds to the acoustic properties of speech. The aim of the present study was to investigate neural activation in adults when listening to native and non-native speech, and to non-speech analogs of speech. We used MEG to examine activation of the superior temporal and inferior parietal areas. Native speakers of Finnish were presented with Finnish (/pa/ and /ta/) and Chinese (/t "looped c" "superscript h" i/ and /"looped c" i/) syllables, and sine-wave replicas of /pa/ and /ta/, in a passive oddball paradigm. Our analysis examines the properties of localized neural activities to determine how activation of sensory and motor speech areas differs for speech and non-speech, and the role of language experience in brain activation.

Toothbrushing-induced epilepsy with structural lesions in the primary somatosensory area

We report three patients with reflex toothbrushing-induced epilepsy associated with small circumscribed structural lesions in the primary somatosensory cortex in close proximity to the hand and speech motor areas. Sensory symptoms were observed at clinical onset with localizing focal ictal and interictal epileptiform discharges on EEG. These cases refine the localization, possible mechanisms of epileptogenesis, and classification of this reflex epilepsy.

Neuronal Dysfunction and Schizophrenia Symptoms

Neuronal Dysfunction and Schizophrenia Symptoms

Neuronal Dysfunction and Schizophrenia Symptoms

Neuronal Dysfunction and Schizophrenia Symptoms

Hemispheric asymmetry, modular variability and age-related changes in the human entorhinal cortex

The verrucae areae entorhinalis (VAE) are a characteristic feature of the human brain that occupy the anterior and posterolateral parts of the parahippocampal gyri and correspond to the islands of layer II neurons. We analyzed VAE in 60 neurologically normal subjects ranging from 23 to 85 years of age using a casting method. In 10 of these subjects the total number of neurons in the entorhinal islands was estimated stereologically using the optical fractionator. The number and surface area of VAE were higher in the left hemisphere compared with the right, and this leftward asymmetry was highly significant. Regression analysis showed a negative correlation between average VAE area and age in both hemispheres, representing a rate loss of about 800 μm 2 per year. The estimated number of neurons obtained with the optical fractionator showed no significant difference between the left and the right hemisphere (468,000±144,000 vs. 405,000±117,000). There was a highly significant negative correlation between neuron numbers and age in both sides. In addition, clusters of small, undifferentiated layer II neurons (‘heterotopias’) were frequently observed in the rostral part of the entorhinal cortex in young and elderly adults. Layer II entorhinal neurons are among the first to show neurofibrillary changes during normal aging. The present data confirm the occurrence of age-related neuron loss in the entorhinal cortex. Considering the consistent projections from ipsilateral auditory association areas that, together with Broca’s motor-speech area (Brodmann areas 44 and 45), show leftward asymmetry from early infancy (such as Brodmann area 22, planum temporale, and area 52 in the long insular gyrus), we speculate that functional lateralization of the human entorhinal cortex may be associated with specialization for memory processing related to language. Due to the dependence of hippocampal formation on entorhinal projections, this finding is also consistent with the greater capacity of the left hippocampus for verbal episodic memory.

The pterion in Turkish male skulls.

This study was conducted to determine the location and type of pterion in Turkish males. The importance of the pterion is its relation to the middle meningeal artery, Broca's motor speech area on the left side, and surgical interventions relating to pathologies of the sphenoid ridge and optic canal. Specific measurements were taken on both sides of 26 Turkish human male skulls, none of which showed any obvious pathology or trauma. The sphenoparietal type of pterion was the most common (96% right side, 79% left side), followed by the frontotemporal (4% right side, 17% left side), and finally the epipteric type (4% left side only). The distances on the right and left sides respectively from the center of the pterion to the frontozygomatic suture were 3.30+/-0.40 cm and 3.44+/-0.39 cm, to the zygomatic arch 4.05+/-0.39 cm and 3.85+/-0.25 cm, to the optic canal 4.39+/-0.40 cm and 4.36+/-0.40 cm, and to the sphenoid ridge 1.40+/-0.33 cm and 1.48+/-0.32 cm. The thickness of the skull at the center of the pterion was 0.41+/-0.14 cm and 0.39+/-0.12 cm on the right and left sides respectively. These findings should be of use in surgical approaches and interventions via the pterion.

Book Review

Book Review