Dependence of the Parameters of Visual Evoked Potentials on the Parameters of a Complex Visual Stimulus (Tests on Humans)

We recorded visual evoked potentials, VEP, elicited by presentation of a reversal chess pattern; 35 healthy persons were examined. A recording electrode was in point Oz, according to the 10-20 system; dimensions of the chess pattern square fields and their contrast varied from 1.8 to 120 and from 2 to 100%, respectively. Peak latencies, PL, of the N75 component depended on the contrast of stimulus elements in a U-like manner with the minimum within a 20-25% range. The PL of the P100 component monotonically increased with a decrease in the contrast, while the dependence of the PL of N145 was complex: a trend toward a decrease with a decrease in contrast to 30%, a local maximum in about 25%, a decrease and stabilization within a 15-4% range, and a sharp increase at the minimum contrast. The amplitude of N75 decreased with decrease in contrast down to 20-25% and then stabilized; the amplitude of P100 decreased in an S-like mode, with a plateau within 25-4%. The dependence of the N145 amplitude was complex, with a plateau-like maximum at 30-15% contrast. The amplitudes of the negative VEP components, N75 and N145, increased with an increase in the square dimensions to 7.5 and then decreased. Changes in the P100 amplitude included two phases, with a local minimum within an angular dimension range of 30-15^O. The PL of all analyzed components in general increased with a decrease in the angular dimension of the pattern components. The above data are discussed considering concepts on the genesis of different VEP components and on the existence of specialized channels in the visual system, which are responsible for detection of different parameters of a visual object. The complex dynamics of the PL of the analyzed VEP components and of the P100 amplitude related to variation of the contrast and angular dimensions of the elements of a complex stimulus are considered to be determined by a module principle of the organization of the elements constituting different levels of the visual system and by transformations of the receptive fields of these elements on the level of cortical modules, which are related to changes in the stimulus parameters.     

Visual Evoked Potentials and Disorders of Visual Function in Children Suffering from Cerebral Palsy

Using recording of visual evoked potentials (VEP), we examined 126 children (from 1 to 14 years old) suffering from spastic forms of cerebral palsy. In the overwhelming majority of cases (84.1%), we found in these patients significant modifications of the VEP related to dysfunctions of the visual analyzer system at different levels of the latter. We analyzed correlation of clinical manifestations of the disease with deviations of the VEP characteristics from the age norm. We conclude that an EEG examination, including VEP recording, allows one to obtain objective estimates of disorders of the visual function in the studied population of patients.     

Modifications of Visual Evoked Potentials in Patients with Glaucoma

We compared the visual evoked EEG potentials (VEP) elicited by presentation of a reversal chess pattern in patients with glaucoma and in the control group. Amplitudes, peak latencies of the main VEP components (N75, P100, and N145), interpeak intervals, and interpeak magnitudes were measured, and a spectral analysis of the averaged VEP was performed. In patients suffering from glaucoma, the latencies of the N75 and P100 components were greater, while the interpeak intervals P100-N145 and N75-N145 were shorter, than those in the control group. Glaucoma-related changes in the VEP spectral characteristics, in particular a drop in the spectral power of oscillations corresponding to the alpha rhythm, were observed.     

正常人眼的多焦视诱发电位特征

研究31只正常眼视野中央8.6度的多焦（多刺激野）视诱发电位(multifocal visual evoked potential, MVEP)在视野各部位的特征.观察到平均反应密度随离心度增加而减少,并且在下半视野比在上半视野相应部位高;在上半视野,MVEP波形的极性反转发生率较高.MVEP在视野中的改变反映了视网膜和大脑视皮层解剖特征及其拓扑投射关系.     

脑干听觉诱发电位与后循环TIA及脑干梗死的相关性研究

目的:研究脑干听觉诱发电位(BAEP)与后循环短暂性脑缺血发作(TIA)及脑干梗死的相关性。方法:选取我院收治的后循环TIA患者46例作为TIA组,选取同期收治的脑干梗死患者44例作为脑干梗死组,选取同期健康体检者49例作为健康组,TIA组和脑干梗死组均在发病后1周内进行BAEP检查,健康体检者在体检时进行BAEP检查,比较3组的Ⅰ、Ⅲ、Ⅴ波的潜伏期(PL)及Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ波峰间的潜伏期(IPL)。结果:TIA组BAEP异常率71.74%,脑干梗死组BAEP异常率56.82%,健康组BAEP异常率24.49%,TIA组患者BAEP异常率高于健康组,差异有统计学意义(P0.05)。脑干梗死组BAEP异常率高于健康组,差异有统计学意义(P0.05)。TIA组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。TIA组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL与PL均明显高于TIA组(P0.05)。结论:BAEP与后循环TIA及脑干梗死存在相关性,并且较为敏感,是优秀的诊断方法之一。     

视觉诱发电位波形的自动判别分析及其临床应用

计算诱发电位波形第一至第六次谐波的幅度和相位,把这12个参数作为判别分析的自变量.用32只正常眼、31只弱视眼和30只球后视神经炎患眼的诱发电位波形数据建立判别分析系统,再用另外32只正常眼、35只弱视眼和30只球后视神经炎患眼的诱发电位波形数据检验该判别分析系统的判别效果.     

Luminance Information Is Required for the Accurate Estimation of Contrast in Rapidly Changing Visual Contexts

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Evoked potential audiometry of 13 Pacific bottlenose dolphins (Tursiops truncatus gilli)

Evoked potential audiograms were measured in 13 Pacific bottlenose dolphins (Tursiops truncatus gilli) to determine the variability in hearing sensitivity and range of hearing. The auditory evoked potential system used a transducer embedded in a suction cup to deliver sinusoidal amplitude modulated tones to each dolphin through the pan region of the lower right jaw. Evoked potentials were recorded noninvasively using surface electrodes, and hearing thresholds were estimated by tracking the amplitude of the envelope following response, an evoked potential that is phase‐locked to the stimulus modulation rate. Frequencies tested ranged from 10 to 180 kHz in each animal. Variability in the range of hearing and age‐related reductions in hearing sensitivity and range of hearing were consistent with those observed in Atlantic bottlenose dolphins. Comparison of audiograms to a captive population of Atlantic bottlenose dolphins demonstrated that the Pacific bottlenose dolphins tested in this study had significantly lower thresholds at frequencies of 40 and 60–115 kHz. Differences in thresholds between the groups are unlikely to be due to methodological factors.     

用子波变换的能量最大准则分析婴儿痉挛症脑干诱发电位

借鉴流体力学中用子波变换识别湍流相干结构的能量最大准则,解释婴儿痉挛症发病的三联征,尤其想说明智能迟滞的原因.从电生理的角度来说明,为什么脑干是婴儿痉挛症的责任病灶——这个生化及病理已经做出的推测.研究发现婴儿痉挛症患儿的脑干通道对外界刺激的反应能力和信息的传递能力与正常儿童有明显差异,借用能量最大准则在湍流中的解释,认为是因为信息传导阻滞引起患儿智能发育的迟滞,并试着提出评价最理想治疗效果的标准.     

预测性编码在视听觉神经活动中的典型表征

现代神经科学研究指出,大脑是外部世界的“预测器”,它能根据先验知识和当前信息对即将到来的感觉信息进行主动估计,从而完成与外部世界的高效交互。预测性编码是描述预期作用机制的主要理论模型,梳理其在解释视、听觉神经现象方面的研究进展,可为深入理解大脑工作模式提供新的理论基础。本文简述了预测性编码的内容;从常用范式、典型现象、面临争议等方面梳理预期与感觉输入相互作用的典型研究;从有预期无刺激的神经表征、预期相关神经振荡模式两方面简述预期独立于刺激的内源性神经表征;进而回顾了支持预测性编码中分级结构的神经生理证据及重要神经结构。最后,本文从深化理论研究、助力疾病诊疗、启发脑-机接口技术等方面对预测性编码相关研究的发展进行了展望。深入理解预测性编码在视、听觉神经活动中的计算模型及神经表征,有望为揭示大脑感知觉神经活动工作模式开辟新途径。     

Evoked Potentials of the Somatic Cortex and EMG Reactions of the Shoulder Muscles Elicited by Passive Extension of the Elbow Joint in Unanesthetized Cats

We recorded electromyographic (EMG) reactions from the flexors of the elbow joint and evoked potentials (EP) from the somatic cortex (fields 3, 4, and 6) of unanesthetized cats. These reactions were elicited by perturbation of an external extensor loading applied to the arm and evoking passive extension of the elbow joint. Perturbation of the loading was performed in two modes: (i) with different fixed force moments within a 0.04–0.2 N·m range, but with a constant rate of change in this moment (3.2 N·m·sec^–1), and (ii) with a constant force moment magnitude (0.2 N·m), but with different rates of change in this moment (from 0.1 to 6.4 N·m·sec^–1). When the elbow joint was passively extended, an EMG response was generated in the m. biceps brachii. The amplitude of this response correlated with the amplitude of perturbation of the external loading, and the time course of the response was rather close to that of the evoked passive moment. It was possible to differentiate several (up to seven) successive components in EP recorded from the three above-mentioned cortical fields; among them, the component N(50–60) was the most stable and clearly manifested. Its amplitude did not depend on the level of external loading and decreased with a decrease in the rate of loading perturbation. The time course of the N(50–60) changed insignificantly with variation of temporal parameters of the stimulus and of the evoked movement. We conclude that the spinal level and the cortical level responsible for formation of the stretch reflex differ significantly from each other in their functional roles. Reactions of the spinal level (which could be characterized by changes in EMG) are to a greater extent related to a change in the position of the limb link, while reactions of the cortical level (EP) are determined by the arrival of information about changes in the forces applied to the joint. Neurons of the somatic cortex, which are excited in the course of the stretch reflex, cannot be considered the main source responsible for generation of the M2 component of the myographic response. It is supposed that the cortical level predetermines the formation of non-reflex motor commands related to motor reflexes closed in the somatic brain cortex.     

The developmental effects of extremely low frequency electric fields on visual and somatosensory evoked potentials in adult rats

Abstract

The purpose of our study was to investigate the developmental effects of extremely low frequency electric fields (ELF-EFs) on visual evoked potentials (VEPs) and somatosensory-evoked potentials (SEPs) and to examine the relationship between lipid peroxidation and changes of these potentials. In this context, thiobarbituric acid reactive substances (TBARS) levels were determined as an indicator of lipid peroxidation. Wistar albino female rats were divided into four groups; Control (C), gestational (prenatal) exposure (Pr), gestational+ postnatal exposure (PP) and postnatal exposure (Po) groups. Pregnant rats of Pr and PP groups were exposed to 50?Hz electric field (EF) (12?kV/m; 1?h/day), while those of C and Po groups were placed in an inactive system during pregnancy. Following parturition, rats of PP and Po groups were exposed to ELF-EFs whereas rats of C and Pr groups were kept under the same experimental conditions without being exposed to any EF during 68 days. On postnatal day 90, rats were prepared for VEP and SEP recordings. The latencies of VEP components in all experimental groups were significantly prolonged versus C group. For SEPs, all components of PP group, P2, N2 components of Pr group and P1, P2, N2 components of Po group were delayed versus C group. As brain TBARS levels were significantly increased in Pr and Po groups, retina TBARS levels were significantly elevated in all experimental groups versus C group. In conclusion, alterations seen in evoked potentials, at least partly, could be explained by lipid peroxidation in the retina and brain.     

促红细胞生成素对脑损伤早产儿NBNA评分、肝肾功能以及脑干听觉诱发电位的影响

目的:探讨促红细胞生成素(EPO)对脑损伤早产儿新生儿神经行为测定(NBNA)评分、肝肾功能以及脑干听觉诱发电位的影响。方法:选取2015年2月~2018年7月期间我院收治的脑损伤早产儿117例,将上述研究对象根据随机数字表法将其分为对照组(n=58)和观察组(n=59),对照组患儿给予常规对症治疗,观察组在对照组的基础上联合EPO治疗,比较两组NBNA评分、肝肾功能以及脑干听觉诱发电位,记录两组患儿治疗期间并发症发生情况。结果:观察组纠正胎龄40周时NBNA评分高于对照组(P<0.05)。两组患儿治疗后峰间期(Ⅰ~Ⅲ波、Ⅲ~Ⅳ波、Ⅰ~Ⅳ波)、潜伏期(Ⅰ波、Ⅲ波、Ⅳ波)均较治疗前降低,且观察组低于对照组(P<0.05)。两组患儿治疗前、后尿素氮(BUN)、肌酐(Cr)、血清谷丙转氨酶(SGPT)、总胆红素(TBIL)比较差异均无统计学意义(P>0.05)。两组患儿动脉导管未闭、新生儿败血症发生率比较差异无统计学意义(P>0.05),而观察组支气管肺发育不良、颅内出血、脑干听觉诱发电位异常等发生率低于对照组(P<0.05)。结论:EPO对脑损伤早产儿具有一定的神经保护作用,能够有效保护受损神经细胞与听觉神经通路,降低脑损伤并发症的发生率,且不影响患儿的肝肾功能。     

小脑重复经颅磁刺激联合吞咽康复训练对脑卒中后吞咽障碍患者吞咽功能、脑干听觉诱发电位和血清神经损伤指标的影响

摘要 目的：观察小脑重复经颅磁刺激（rTMS）联合吞咽康复训练对脑卒中后吞咽障碍患者脑干听觉诱发电位、吞咽功能和血清神经损伤指标的影响。方法：纳入我院于2019年10月-2021年3月期间收治的60例脑卒中后吞咽障碍患者。按照随机数字表法分为对照组（给予吞咽康复训练,30例）和观察组（给予小脑rTMS联合吞咽康复训练,30例）,均治疗3周。观察两组治疗3周后的临床总有效率,对比两组治疗前、治疗3周后的吞咽功能、脑干听觉诱发电位和血清神经损伤指标。结果：观察组的临床总有效率高于对照组（P<0.05）。观察组治疗3周后改良曼恩吞咽能力评估量表（MMASA）评分升高,且高于对照组（P<0.05）。观察组治疗3周后波潜伏期（Ⅰ、Ⅲ、Ⅳ）、波峰间潜伏期（Ⅰ~Ⅲ,Ⅲ~Ⅳ,Ⅰ~Ⅳ）降低,且低于对照组（P<0.05）。观察组治疗3周后血清视锥蛋白样蛋白1（VILIP-1）、神经肽Y（NPY）、神经元特异性烯醇化酶（NSE）、扣针蛋白5（Fibulin-5）水平降低,且低于对照组（P<0.05）。结论：小脑rTMS联合吞咽康复训练可有效改善脑卒中后吞咽障碍患者的吞咽功能,减轻神经损伤,缩短脑干听觉诱发电位的潜伏期。     

Somatosensory evoked potentials of median and tibial nerves in rhesus monkeys (Macaca mulatta) under captivity: influence of ontogenic status in neonatal, infant, young, adult, and senile stages

Background Somatosensory evoked potentials (SEPs) constitute a useful neurophysiologic tool commonly used to assess the functionality and developmental degree of the nervous system. Objective To analyze somatosensory pathways of the Macaca mulatta species throughout different ontogenetic statuses. Methods Twenty non‐human primates were divided into five age‐dependant groups. Recording of SEPs was executed by stimulation of lower limb at the tibial nerve and upper limb and recorded at the median nerve. Results Two wave series were observed for all groups for both limbs studied. Significant differences were found at the upper right limb at C4, C7 and also for the antecubital fossa site. The lower limbs showed a single significant right‐wing deflection. Conclusions Differences found in signals generated by the nervous system in response to somatosensory stimuli among the studied groups are thought to be developmental in origin, as the most remarkable deviations were seen in younger monkeys.     

Intraretinal variability and specialization of cones in Japanese anchovy (Engraulis japonicus,Engraulidae)

The retina of anchovies is characterized by an unusual arrangement and ultrastructure of cones. In the retina of Japanese anchovies, Engraulis japonicus, three types of cones are distributed into rows. The nasal, central, temporal, and ventro‐temporal regions of the retina were occupied exclusively by the long and short cones. Triple cones, made up of two lateral components and one smaller central component, were found only in the dorsal and ventro‐nasal retinal regions. In the outer segments of all short and long cones from the ventro‐temporal region, the lamellae were oriented along the cell axis and were perpendicular to the lamellae in the long cones, providing a morphological basis for the detection of polarization. This lamellar orientation is unique to all vertebrates. The cones were examined with respect to regional differentiation in their size and spectral properties via light microscopy, transmission electron microscopy, and microspectrophotometry. Various dimensions of cones were measured in preparations of isolated cells. The cones from the ventro‐temporal region had different dimensions than cones of the same type located in other retinal regions. Triple cones from the dorsal region were significantly larger than triple cones from the ventro‐nasal region. The spectral absorbance of the lateral components of triple cones in the ventro‐nasal retina was identical to the absorbance of all long and short cones from the ventro‐temporal region. These are shifted to shorter wavelengths relative to the absorbance of the lateral components of the triple cones located in the dorsal retina. Thus, the retina of the Japanese anchovy shows some features of regional specialization common in other fishes that improves spatial resolution for the upwards and forwards visual axis and provides spectral tuning in downwelling light environment. That results from the differentiation of cone types by size and by different spectral sensitivity of various retinal areas. J. Morphol. 277:472–481, 2016. © 2016 Wiley Periodicals, Inc.