Involvement of the parietal cortex in perceptual learning (Eureka effect): An interference approach using rTMS

The neural mechanisms underlying perceptual learning are still under investigation. Eureka effect is a form of rapid, long-lasting perceptual learning by which a degraded image, which appears meaningless when first seen, becomes recognizable after a single exposure to its undegraded version. We used online interference by focal 10-Hz repetitive transcranial magnetic stimulation (rTMS) to evaluate whether the parietal cortex (PC) is involved in Eureka effect, as suggested by neuroimaging data. RTMS of the PC did not affect recognition of degraded pictures when displayed 2 s after the presentation of their undegraded version (learning phase). However, rTMS delivered over either right or left intraparietal sulcus simultaneously to the undegraded image presentation, disrupted identification of the degraded version of the same pictures when displayed 30 min after the learning phase. In contrast, recognition of degraded images was unaffected by rTMS over the vertex or by sham rTMS, or when rTMS of either PC was delivered 2 s after the presentation of the undegraded image. Findings strongly support the hypothesis that both PC at the level of the intraparietal sulcus play a pivotal role in the Eureka effect particularly in consolidation processes, and contribute to elucidate the neural network underlying rapid perceptual learning.     

Effects of Middle-Ear Disease and Cleft Palate on High-Frequency Hearing in Children

High-frequency hearing loss in children with cleft palate has been documented recently. The present study was designed to investigate whether hearing loss can result solely as a consequence of middle-ear disease in early life or as a result of cleft palate and its sequelae which include middle-ear disease. Our results demonstrate that auditory functions for test frequencies 250-6 000 Hz were not significantly different among the two investigational groups of children with high incidence of middle-ear disease, and a control group of children with virtually no middle-ear disease. However, for high-frequency thresholds (8 000-20 000 Hz), both groups of children with high incidence of middle-ear disease were statistically different from the control group. Moreover, the children with cleft palate had high-frequency hearing that was statistically similar to that of children with normal orofacial structures and high incidence of middle-ear disease. Middle-ear disease alone, then, is a sufficient condition for loss of high-frequency sensitivity.

La perte auditive des hautes fréquences chez les enfants porteurs d'une fissure palatine a fait l'objet d'une documentation récente. Cette étude a été organisée de façon à établir si la perte auditive pouvait résulter uniquement d'une maladie de l'oreille moyenne dans la petite enfance, ou d'une fissure palatine et de ses séquelles qui comprennent les otites moyennes. Entre les deux groupes d'enfants prédisposés aux otites moyennes, et un groupe de contro?le constitué d'enfants rarement atteints d'otites moyennes, nos résultats n'indiquent pas de différences significatives quant aux fonctions auditives pour des fréquences d'essai de 250 à 6 000 Hz. Néanmoins, en ce qui concerne les seuils aux hautes fréquences (de 8 000 à 20 000 Hz), les deux groupes d'enfants prédisposés aux otites moyennes étaient statistiquement différents du groupe de contro?le. En outre, les enfants porteurs d'une fissure palatine avaient une audition des hautes fréquences qui était statistiquement semblable à celle des enfants porteurs de structures orofaciales normales et qui étaient prédisposés aux otites moyennes. A elle seule, une atteinte de l'oreille moyenne semble done ětre une condition suffisante pour l'apparition d'une perte auditive sur les hautes fréquences.     

Low-Frequency Hearing Loss: Auditory Brainstem Response-Derived Band Analysis

Conventional (0.125-8 kHz) and high-frequency (8-20kHz) audiometry, together with brainstem response audiometry supplemented with derived-band studies have been performed in 6 patients with sensorineural hearing loss: 1 with narrow-band, 3-4 kHz, and 5 with low-frequency threshold elevations. The derived-band results in the latter indicate that the low-frequency audiometric thresholds are spurious, and represent the low-frequency tails of viable high-frequency neurons. Threshold preservation in the 4- to 8-kHz frequency band proved necessary for generation of a normal auditory brainstem response at suprathreshold stimulus levels.

On a étudié sur 6 patients présentant une surdité de perception l'audiogramme conventionnel (0.125-8 kHz) et haute-fréquence (8-20 kHz), ainsi que les potentiels précoces dérivés: l'élévation de seuil était limitée à une bande étroite, 3-4 kHz, chez 1 patient, et intéressait les basses fréquences pour les 5 autres. La technique des potentiels dérivés sur ces derniers sujets montre que les seuils audiométriques sur les graves sont faux et représentent en fait les extrémités basse-frequence de neurones haute-fréquence demeurés sains. La préservation de l'audition au niveau de la bande 4-8 kHz est nécessaire à l'obtention de potentiels précoces normaux aux niveaux supraliminaires.     

Behaviour of High-Frequency Hearing in Noise

Because of an improved coupling and of special loudspeakers high-frequency (HF) audiometry may now be used for routine audiometry. Examinations of 200 weaving-mill workers showed hearing threshold levels with a broad dip at about 4 or 6 kHz but with relatively good hearing at about 11 and 12 kHz. The greatest hearing threshold shifts were observed at 15 kHz and above. The course of the curves clearly showed a dependence on the noise level. With most cases of acute acoustic traumata there was a total loss in the HF range reaching far into the frequency range of normal hearing. This pattern is correlated with the area of destruction of the hair cells in the cytocochleogram. Another characteristic course of the curves was marked by an extreme hearing loss in the HF range showing, however, a horizontal course. A similar cytohistogram could not be found in the literature.     

The Role of High-Frequency Audiometry in Early Detection of Ototoxicity

Ototoxicity is one of the unwanted side-effects of a number of medical drugs. As ototoxicity appears to be most pronounced in the higher frequencies, it can be assessed at an earlier stage by using high-frequency audiometry from 8 to 20 kHz. We have investigated the precision of these measurements. In spite of inaccuracies of headphone positioning, which may influence especially the high-frequency thresholds, standard deviations for frequencies above 8 kHz were obtained that were nearly as small as for audiometry up to 8 kHz. Age-related reference curves for the higher frequencies are presented. The results on 100 ears of patients treated with platinum-derivatives show the importance of high-frequency audiometry for the early detection of ototoxicity.

Certains médicaments ont un effet toxique sur l'oreille interne (ototoxicité). Cet effet se produit d'abord au niveau des hautes fréquences et peut ětre détecté plus töt par audiométrie dans les fréquences de 8 à 20 kHz que par audiométrie conventionnelle. Bien que la position des écouteurs sur la těte puisse influencer le seuil des hautes fréquences, nous avons obtenu des écarts-types presqu'aussi petits qu'avec audiométrie jusqu'à 8 kHz. Des courbes de référence en fonction de l'aˇge sont présentées. L'importance de l'audiométrie dans les hautes fréquences pour la détection précoce d'un effet ototoxique est démontrée à partir des résultats obtenus chez 100 malades traités par des dérivés du platine.     

Reliability of Auditory Brainstem Responses from Sequenced High-Frequency (≥ 8 kHz) Tonebursts

An auditory brainstem response method is described for evoking responses to 4 high-frequency (8, 10,12 and 14 kHz) tone-bursts in the same amount of time normally required to obtain responses to single tonebursts. Reliability of responses to high-frequency toneburst stimuli presented in the conventional manner (one at a time) has been previously documented. In the present study, high-frequency tonebursts were presented to 20 normal-hearing subjects singly and in a 4-stimulus sequence. The reliability of resulting responses did not differ significantly between single- and multiple-stimulus test conditions. It is concluded that this sequenced-stimulus concept could be developed for use in serial monitoring of individuals receiving ototoxic agents as well as being broadly applicable to clinical situations in which patients cannot or will not respond voluntarily.     

高频超声对先天性肥厚性幽门狭窄的诊断价值

目的:探讨高频超声对先天性肥厚性幽门狭窄(CHPS)的诊断价值。方法:回顾性分析36例经手术及病理证实为CHPS患儿的高频超声特征,测量幽门肌层厚度、幽门管长度、直径并计算狭窄指数(SI)。随机选取20例健康婴幼儿为正常组,对其高频超声测值与CHPS组进行分组比较,同时对CHPS组术前高频超声测值与术中测值进行配对比较。结果:CHPS组高频超声测量幽门肌层厚度(5.0±0.61)mm,幽门管长度(23.3±2.15)mm,幽门管直径(15.6±2.14)mm,幽门狭窄指数(78.1±12.50)%。正常组幽门肌层厚度(1.6±0.52)mm,幽门管长度(12.3±2.50)mm,幽门管直径(10.2±1.10)mm,幽门狭窄指数(25.6±4.10)%。正常组与CHPS组比较差异均有显著统计学意义(P<0.01),CHPS组术前超声测值与术中测值配对比较无显著性差异(P>0.05)。结论:高频超声对CHPS的诊断简便易行、准确可靠,避免患儿吞钡和X线照射以及减少误吸,具有重要的临床应用价值。     

Characteristics of the sequence effect in Parkinson's disease

The sequence effect (SE) in Parkinson's disease (PD) is progressive slowing of sequential movements. It is a feature of bradykinesia, but is separate from a general slowness without deterioration over time. It is commonly seen in PD, but its physiology is unclear. We measured general slowness and the SE separately with a computer‐based, modified Purdue pegboard in 11 patients with advanced PD. We conducted a placebo‐controlled, four‐way crossover study to learn whether levodopa and repetitive transcranial magnetic stimulation (rTMS) could improve general slowness or the SE. We also examined the correlation between the SE and clinical fatigue. Levodopa alone and rTMS alone improved general slowness, but rTMS showed no additive effect on levodopa. Levodopa alone, rTMS alone, and their combination did not alleviate the SE. There was no correlation between the SE and fatigue. This study suggests that dopaminergic dysfunction and abnormal motor cortex excitability are not the relevant mechanisms for the SE. Additionally, the SE is not a component of clinical fatigue. Further work is needed to establish the physiology and clinical relevance of the SE. © 2010 Movement Disorder Society.     

高频电刀处理家兔牙髓对牙周组织表面温度变化的实验研究

目的利用红外线测温技术测量高频电刀处理家兔牙髓时牙周组织表面的温度变化,初步评估高频电刀产生的高热可能对牙周组织的影响程度。方法选取20只3月龄的健康实验家兔,共40颗上颌门齿,再随机分成4个小组。在上腭黏膜标记好固定测温点,分别使用5.0 W、10 W、15 W、20 W输出功率的高频电流处理相应小组的家兔牙髓(分别处理冠髓或根髓),并同步对已标记的2个测温点测温,根据温度变化的数据进行统计学分析。结果经高频电刀处理牙髓前后的牙周组织表面温度变化值在-0.02℃～2.61℃之间;处理冠髓时,使用15 W及以上功率的,两测温点有统计学差异;处理根髓时,使用20 W功率的,两测温点有统计学差异;使用10 W及以上功率分别处理冠髓和根髓,牙颈部和根尖的温度变化有统计学差异。结论使用4种输出功率处理家兔牙髓,牙周组织表面温度的变化值(-0.02℃～2.61℃),都在对牙周组织不造成副损伤的安全阈值内。由此,我们认为,使用20 W以内输出功率处理家兔牙髓时,对根尖周的热损伤不会太大。