Yoshikazu Kikuchi

Spatiotemporal signatures of an abnormal auditory system in stuttering.

People who stutter (PWS) can reduce their stuttering rates under masking noise and altered auditory feedback; such a response can be attributed to altered auditory input, which suggests that abnormal speech processing in PWS results from abnormal processing of auditory input. However, the details of this abnormal processing of basic auditory information remain unclear. In order to characterize such abnormalities, we examined the functional and structural changes in the auditory cortices of PWS by using a 306-channel magnetoencephalography system to assess auditory sensory gating (P50m suppression) and tonotopic organization. Additionally, we employed voxel-based morphometry to compare cortical gray matter (GM) volumes on structural MR images. PWS exhibited impaired left auditory sensory gating. The tonotopic organization in the right hemisphere of PWS is expanded compared with that of the controls. Furthermore, PWS showed a significant increase in the GM volume of the right superior temporal gyrus, consistent with the right tonotopic expansion. Accordingly, we suggest that PWS have impaired left auditory sensory gating during basic auditory input processing and that some error signals in the auditory cortex could result in abnormal speech processing. Functional and structural reorganization of the right auditory cortex appears to be a compensatory mechanism for impaired left auditory cortex function in PWS.

Abnormal auditory synchronization in stuttering: A magnetoencephalographic study.

&NA; In a previous magnetoencephalographic study, we showed both functional and structural reorganization of the right auditory cortex and impaired left auditory cortex function in people who stutter (PWS). In the present work, we reevaluated the same dataset to further investigate how the right and left auditory cortices interact to compensate for stuttering. We evaluated bilateral N100m latencies as well as indices of local and inter‐hemispheric phase synchronization of the auditory cortices. The left N100m latency was significantly prolonged relative to the right N100m latency in PWS, while healthy control participants did not show any inter‐hemispheric differences in latency. A phase‐locking factor (PLF) analysis, which indicates the degree of local phase synchronization, demonstrated enhanced alpha‐band synchrony in the right auditory area of PWS. A phase‐locking value (PLV) analysis of inter‐hemispheric synchronization demonstrated significant elevations in the beta band between the right and left auditory cortices in PWS. In addition, right PLF and PLVs were positively correlated with stuttering frequency in PWS. Taken together, our data suggest that increased right hemispheric local phase synchronization and increased inter‐hemispheric phase synchronization are electrophysiological correlates of a compensatory mechanism for impaired left auditory processing in PWS. HighlightsPeople who stutter (PWS) have significantly delayed left‐only N100m latency.PWS have increased local phase synchronization in the alpha band.PWS show increased inter‐hemispheric synchronization in the beta band.Right hemisphere hyperactivity offsets impaired left hemispheric function in PWS.

A case of multiple system atrophy-parkinsonian type with stuttering- and palilalia-like dysfluencies and putaminal atrophy

Both developmental and acquired stuttering are related to the function of the basal ganglia-thalamocortical loop, which includes the putamen. Here, we present a case of stuttering- and palilalia-like dysfluencies that manifested as an early symptom of multiple system atrophy-parkinsonian type (MSA-P) and bilateral atrophy of the putamen. The patient was a 72-year-old man with no history of developmental stuttering who presented with a stutter for consultation with our otorhinolaryngology department. The patient was diagnosed with MSA-P based on parkinsonism, autonomic dysfunction, and bilateral putaminal atrophy revealed by T2-weighted magnetic resonance imaging. Treatment with levodopa improved both the motor functional deficits related to MSA-P and stuttering-like dysfluencies while reading; however, the palilalia-like dysfluencies were much less responsive to levodopa therapy. The patient died of aspiration pneumonia two years after his first consultation at our hospital. In conclusion, adult-onset stuttering- and palilalia-like dysfluencies warrant careful examination of the basal ganglia-thalamocortical loop, and especially the putamen, using neuroimaging techniques. Acquired stuttering may be related to deficits in dopaminergic function.

Kinematic evaluation of penetration and aspiration in laryngeal elevating and descending periods

It is important to evaluate swallowing movements by dividing them into periods of laryngeal closure and release. The purpose of this study was to evaluate penetration–aspiration (PA) according to human pathophysiology and to identify the factors for predicting PA.

Altered neural synchronization to pure tone stimulation in patients with mesial temporal lobe epilepsy: An MEG study

OBJECTIVE Our previous study of monaural auditory evoked magnetic fields (AEFs) demonstrated that hippocampal sclerosis significantly modulated auditory processing in patients with mesial temporal lobe epilepsy (mTLE). However, the small sample size (n = 17) and focus on the M100 response were insufficient to elucidate the lateralization of the epileptic focus. Therefore, we increased the number of patients with mTLE (n = 39) to examine whether neural synchronization induced by monaural pure tone stimulation provides useful diagnostic information about epileptic foci in patients with unilateral mTLE. METHODS Twenty-five patients with left mTLE, 14 patients with right mTLE, and 32 healthy controls (HCs) were recruited. Auditory stimuli of 500-Hz tone burst were monaurally presented to subjects. The AEF data were analyzed with source estimation of M100 responses in bilateral auditory cortices (ACs). Neural synchronization within ACs and between ACs was evaluated with phase-locking factor (PLF) and phase-locking value (PLV), respectively. Linear discriminant analysis was performed for diagnosis and lateralization of epileptic focus. RESULTS The M100 amplitude revealed that patients with right mTLE exhibited smaller M100 amplitude than patients with left mTLE and HCs. Interestingly, PLF was able to differentiate the groups with mTLE, with decreased PLFs in the alpha band observed in patients with right mTLE compared with those (PLFs) in patients with left mTLE. Right hemispheric predominance was confirmed in both HCs and patients with left mTLE while patients with right mTLE showed a lack of right hemispheric predominance. Functional connectivity between bilateral ACs (PLV) was reduced in both patients with right and left mTLE compared with that of HCs. The accuracy of diagnosis and lateralization was 80%-90%. CONCLUSION Auditory cortex subnormal function was more pronounced in patients with right mTLE compared with that in patients with left mTLE as well as HCs. Monaural AEFs can be used to reveal the pathophysiology of mTLE. Overall, our results indicate that altered neural synchronization may provide useful information about possible functional deterioration in patients with unilateral mTLE.

P529: Abnormal auditory synchronization in stuttering: a magnetoencephalographic study

Question: Modulation of the 20-Hz rolandic rhythm to somatosensory input has been proposed to reflect alterations in the motor cortex excitability. In stroke patients, the strength of this modulation is associated with recovery of hand function. In this study we compared the suppression and rebound amplitudes of the 20-Hz (15-25 Hz) rhythm to tactile stimulation and passive movement. Methods: We recorded rhythmic brain activity in 22 healthy subjects (11 males, mean 59 years) with a 306-channel MEG system during tactile stimulation and passive movement. Tactile stimuli were delivered using pneumatic diaphragms to both index fingers alternately with an interstimulus interval of 1.5 s. For passive movements, the subjects’ index fingers were lifted by a nurse every 3 s. Suppression and rebound of the 20-Hz rhythm were analyzed using Temporal Spectral Evolution (TSE) and their amplitudes were quantified from the MEG channel displaying the strongest rebound/suppression. Results: The peak amplitudes of the rebound in both ipsiand contralateral hemispheres were significantly (p<0.05) stronger after passive movement than after tactile stimulation. In contrast, the peak amplitudes of the suppression did not significantly differ between the stimuli. Conclusions: According to our results, passive movements are strong modulators of the motor cortex excitability. Thus, passive movement might be a more robust and feasible tool than tactile stimulation to study motor cortex alterations in stroke patients.

13. Suppression of auditory P50m in stuttering: A magnetoencephalography(MEG) study

The effectiveness of CPAP therapy on central sleep apnea (CSA) remains controversial and factors associated with such effectiveness are still unclear. We investigated effectiveness of CPAP on CSA and related factors, focusing on body position during sleep and presence or absence of underlying cardiac dysfunction. Among 7268 subjects who underwent polysomnography, 115 patients who had central apnea hypopnea index (CAHI) P15 were analyzed. We excluded 47 patients who had rarely lateral position during sleep (<20%). We found 34 subjects (50%) showed significant reductions in AHI on CPAP (i.e. effective group, defined AHI 65 on CPAP or >80% reduction from the diagnostic AHI) whereas residual 34 subjects did not show such reductions (i.e. ineffective group). Ineffective group showed significantly greater AHI on lateral position (L-AHI) and lower % of slow wave sleep (%SWS) on diagnostic study, and more frequently had cardiac dysfunction as compared with effective group. Multivariate logistic regression analysis showed greater LAHI, lower %SWS and presence of cardiac dysfunction are independently associated with the CPAP-ineffectiveness. Our findings suggest that in addition to the underlying cardiac dysfunction, CSA on lateral position may play a role to determine CPAP effectiveness on CSA.