足月新生儿听觉脑干电反应的特性

本文工作根据北京市儿童医院临床的需要,在临床实验条件下对足月新生儿的ABR进行了测量,以期分析足月新生儿ABR的电反应特征。 新生儿听觉脑干反应(ABR)的波形是Ⅰ、Ⅲ、Ⅴ波为主的连续波复合体;新生儿在声强80dB(HL)刺激频率20次/秒的短声刺激条件下,I、Ⅲ、Ⅴ波潜伏期大体为2.50,5.00和7.00ms;新生儿ABR潜伏期—刺激强度函数的斜率是30—60μsec/dB(声刺激强度从80到50dB(HL),声刺激频率20次/秒);新生儿ABR Ⅴ波对Ⅰ波的比率大于1.0(短声强度80dB(HL),刺激频率20次/秒);在80dB(HL)短声条件下,改变声刺激频率(从20次/秒增止100次/秒),Ⅴ波潜伏期约延长0.6—1.0ms;新生儿ABR阈值在30—60dB(HL)的范围。综上所述新生儿ABR电反应特性,可以为其听力和脑干功能的临床诊断提供可靠的指标和依据。     

小鼠下丘神经元声刺激跟随力与声时程及强度的关系

自由声场条件下,通过给予小鼠具有不同时程(10、40及100ms)、强度(最小阈值以上5、15、25、35及45dBSPL)、呈现率(0.5、1、2、3.3、5、6.7、10和20Hz)的纯音短声刺激,分析探讨了昆明小鼠下丘神经元声刺激跟随力与声时程及强度的关系。结果发现:多数神经元的脉冲发放数随声强增高而增加,随短声时程的延长而减少;随声强的增高,多数神经元的临界呈现率(CPR)和最大呈现率(MPR)变大,而随短声时程的延长,神经元的CPR、MPR变小为主要趋势;下丘神经元的声反应跟随力总体上随时程延长而下降,随声强加大而提高。推测当声时程延长、强度下降时,前次刺激对后继刺激声反应的抑制性影响增强,提示声时程适当缩短、声强增大可能有助于下丘神经元汇聚更多的声信息进行高级神经处理,从而提高听中枢表征高密度声信息的能力。     

有关猫交叉听力及其对检测耳影响的初步研究

目的研究猫的交叉听力现象及其产生机理,初步探讨交叉听力对检测耳ABR振幅的影响。方法用彻底破坏一侧耳蜗的方法,观察16只听力正常家猫的交叉听力现象及其对检测耳的影响。结果①当短声强度≥75dB(SPL)时,开始出现交叉听力波形,声强增至95dB时,交叉听力波形最典型。②95dB短声产生的交叉听力波形可被40或45dB(SPL)的稳态白噪声（SWN）完全屏蔽掉。③在同一时间轴中比较95dB短声诱发的ABR和交叉听力波形,发现交叉听力之波谷恰与ABR之pⅢ、pⅣ波峰相对应。④两耳均正常时对侧耳负荷的40dBSWN可使95dB短声诱发的ABR之pⅢ、pⅣ波振幅增大,且具统计学意义（P＜0.01）。结论交叉听力对ABR振幅的影响取决于两者的波峰与波谷在同一时间轴上的对应情况,声强较大时记录到的ABR,实质上是交叉听力与刺激侧产生的ABR在同一时间轴上的综合电位。     

成对短声不同间隔对单、双耳听觉脑干反应的影响——衍生听觉脑干反应方法的应用

采用具有不同间隔(0～32ms)的65dB nHL(正常听力水平)的成对短声刺激,记录20名正常人的单侧耳和两耳交替刺激的听觉脑干反应(ABR)。用计算机从成对短声反应中减去单一短声反应以提取衍生ABR。结果表明,单、双耳的衍生ABR V波振幅在成对短声间隔为0.2～1.5ms时,受到明显影响。单耳的减小54％～65％(P<0.01),两耳的减少46％～53％(P<0.01),但单、双耳的衍生ABR I波振幅未显示显著差异(P>0.05)。该结果说明,高位脑干通路在成对短声间隔为0.2～1.5ms时,不但对同侧耳的第2个短声反应能力降低,而且对来自对侧耳的第2个短声也如此。从而推断,在两耳交替刺激的耳间短声间隔小于2ms范围时,在下丘部位可能存在两耳交互作用。结果还提示,临床检查ABR时,采用的短声刺激间隔至少不应小于30ms。     

葡萄糖添加对室温和冻结过程土壤N_2O排放特征影响

为明确外源葡萄糖添加对典型耕作土壤室温和冻结过程N_2O排放特征,应用控制室温和冰柜模拟土壤培养方法,研究室温和冻结过程葡萄糖添加(0、1.5、2.5 mg·g~(–1))对3种典型地带性耕作土壤(黑土、潮土、黄土)N_2O排放的影响。结果表明,室温条件下1.5和2.5 mg·g~(–1)外源葡萄糖添加黑土N_2O排放通量分别比不添加处理增加604.3%和1198.5%,均达5%显著性差异;外源葡萄糖添加显著抑制潮土N_2O排放;3种葡萄糖水平下黄土N_2O排放通量始终处于极低的水平。随冻结过程的进行,黑土和不添加葡萄糖的潮土N_2O排放通量逐渐降低并维持零排放速率;添加葡萄糖处理的潮土N_2O排放通量始终维持零排放速率的水平;黄土N_2O排放通量始终维持在–25-20μg·(m~2·h)~(–1)范围内,甚至出现负排放。与潮土和黄土相比较,常温和冻结过程中添加葡萄糖的黑土需更关注N_2O的排放。     

蟾蜍延脑听中枢的单位电反应的一些观察

我们利用电生理学的方法测定了蟾蜍延脑听反应的区域,并研究了延脑听神经元对短声及纯音的反应特性。结果表明:1.从内耳来的传入冲动主要是向同侧的延脑听区传递的。2.蟾蜍听觉系统感受的频率范围在4,000周/秒以下,对于500—600周/秒以及1,000—1,200周/秒的频率最为敏感。多数听神经元的反应阈值在人听阈上25—35分贝左右。少数在人听阈上5—10分贝或45—55分贝。3.根据短声及特征频率的纯音所引起的反应,可将延脑听神经元的反应分为长潜伏期(平均约12毫秒)及短潜伏期(平均约3毫秒)两种形式。反应潜伏期的长短,可能是由不同类型的神经元的特性所决定的,但在同一神经元,在改变声音刺激的频率或强度时,反应的潜伏期也有变化。4.延脑听神经元对纯音刺激的反应有连续发放的、给声的、给-撤声的以及撤声的几种形式。其中以连续发放的反应形式最为常见。5.有时,纯音引起的连续发放是迭加在振幅达十几毫伏的正相慢波之上的,发放的波形为正单相锋形电位,它的上升相较陡,下降相缓慢。短声也可以引起这样的锋形电位,它们可能是细胞内记录到的反应。     

我国正常成人脑干听觉电反应各波潜伏期的测定

在10名正常被试者的20只耳,用不同强度的短声测定了脑干听觉电反应(BSR)的7个波的潜伏期(数值见表1),结果表明,各波的潜伏期都随刺激声强的减弱(80到0 dB)而延长,且呈直线函数关系,并且这种延长主要来自1波。由每个被试者两耳所诱发的 BSR 各波的潜伏期及其与刺激声强的变化关系都较为恒定和对称。V 波振幅较大,出现率较高,接近主观听觉阈值,是 BSR 中的主波,其潜伏期(声强80 dB 时为5.7±0.6毫秒)如明显超出此范围(6.3毫秒)或两侧不对称时,应考虑为异常。我们还在半数测试例中记录到Ⅷ波,关于它的生理意义,尚不清楚。     

关于光刺激所引起的大■复眼和视叶综合电反应的研究

(一)用一个10％ K_4Fe(CN)_6灌注的玻璃微电极記录了大蠊复眼及視叶不同深度部位对光刺激的电反应。这个电极是从对侧复眼插入的,它同时又与另外一个固定的角膜下电极作为辨差引导。对某些深度的电反应曾加以分析。 (二)电极接触基底膜时,无例外地产生一种振动电位;根据基底膜的位置卽可准确地断定复眼及視叶其他結构的位置。对复眼和视叶的結构曾簡单地加以描述。 (三)用小光点(直徑150μ)、光环(內徑150μ,外徑約1mm)和圓形光(直徑約1mm)刺激,檢查了視网膜电图的相加性和波形是否因刺激形状的不同而有所改变。結果表明,大蠊复眼視网膜电图是完全可以相加的,单相引导出的电位的形状与刺激光的形状无关。沒有証据指示在昆虫复眼有相当于脊椎动物的局部視网膜电图的存在。 (四)大蠊視网膜电图为一純负波,在这个负波里,可区別两个成分,N_1和N_2,它們在整个小网膜細胞层都可以不衰减地被記录出来;在基底膜紧下,主要只記录到N_2。視叶的外髓层也有一个正向电位反应,但它的电場不到达复眼。 (五)漸次增强明适应,N_1比N_2更快被压抑。 (六)对于大蠊視网膜电图某些部分的起源以及与其他某些昆虫的不同,本文曾加以讨論。     

兔内膝体神经元对短声引起的晚放电一些特性的观察

实验在118只以三碘季铵酚麻痹的兔上进行。微电极记录短声引起的内膝体神经元反应,在157个单位中,有9个单位表现出两次放电反应(占5.7%)。第一次反应(早放电)的潜伏期为10—13ms,第二次反应(晚放电)为20—28ms,后者的出现与声刺激强度有关,当声强度减至30dB 时,晚放电消失,而早放电不变。静脉注射盐酸氯丙嗪(6mg/kg)后,晚放电被阻抑,早放电仍然不变,85分钟后晚放电重新出现。以上实验结果提示,晚放电可能是听觉冲动经由脑干网状结构多突触上行途径传至内膝体的结果。     

抑制性频谱整合对大棕蝠下丘神经元声强敏感性的影响

自由声场条件下 ,采用特定双声刺激方法研究了不同频率通道之间的非线性整合对下丘神经元声强敏感性的调制作用。实验在 1 2只麻醉与镇定的大棕蝠 (Eptesicusfuscus)上进行 ,双电极同步记录 2个配对神经元的声反应动作电位。主要结果如下 :1 )所获 1 1 0个 (5 5对 )配对神经元中 ,85 5 %表现为抑制性频谱整合作用 ,其余 1 4 5 %为易化性频谱整合 ;2 )阈上 1 0dB (SPL)放电率抑制百分比与神经元最佳频率 (BF)及记录深度呈负相关 ;3)抑制效率随声刺激强度升高而逐步下降 ;4 )当掩蔽声分别位于神经元兴奋性频率调谐曲线(FTC)内 (MSin) /外 (MSout)时 ,其抑制效率存在差异。前者的放电率抑制百分比及声反应动力学范围(DR)下降百分比均显著高于后者 ;5 )抑制性频谱整合导致 3类DR改变 :6 1 6 %为下降、 1 0 9%增加、另有2 7 5 %变化小于 1 0 %。本结果进一步支持如下设想 :下丘不同频率通道之间的抑制性频谱整合参与了对强度编码的主动神经调制活动     

听神经复合动作电位适应性的定量研究

本文研究了短声串作为刺激时,听神经复合动作电位(CAP)中发生的掩蔽作用随短声串的各项参数变化的关系.结果表明:①双短声诱发的CAP中掩蔽作用随两个短声间距的增大而减小;②掩蔽声越强,或被掩蔽声越弱,掩蔽作用越明显.恢复所需的时间也越长;③掩蔽作用随掩蔽声个数的增多而增大,当个数增大到一定数目时,掩蔽作用趋于饱和.     

Dopaminergic modulation of the P50 auditory-evoked potential in a computer model of the CA3 region of the hippocampus: its relationship to sensory gating in schizophrenia

 We modeled the neuronal circuits that may underlie a sensory-processing deficit associated with schizophrenia. Schizophrenic patients have small P50 auditory-evoked responses to click stimuli compared to normal subjects. The P50 auditory-evoked response is a positive waveform recorded in the EEG approximately 50 ms after the auditory click stimulus. In addition to relatively small amplitudes, schizophrenic patients do not gate or suppress the P50 auditory-evoked response to the second of two paired-click stimuli spaced 0.5 s apart. Neuropleptic medication, which decreases dopaminergic neuronal transmission, increases the amplitude of the P50 auditory-evoked response but does not improve gating. Normal subjects have large P50 auditory-evoked responses to click stimuli when compared to unmedicated schizophrenic patients, and they gate their response to paired click stimuli or have smaller P50 auditory-evoked response amplitudes to the second of two click stimuli spaced 0.5 s apart. Schizophrenic patients do not gate and have similar response amplitudes to both clicks. We hypothesized that the small amplitudes of unmedicated schizophrenic subjects were due to a state of occlusion whereby excessive background noise in local circuits reduced the ability of cells to respond synchronously to sensory input, thereby reducing the amplitude of the P50 waveform in the EEG. Because the P50 auditory-evoked potential amplitudes increased with neuroleptic medication, which reduces dopaminergic neuronal transmission, we hypothesized a role for dopamine in modulating the signal-to-noise (S/N) in the local circuits responsible for sensory gating. To test the hypothesis that modulation of the S/N ratio reduces sensory gating, we developed a model of the effects of dopaminergic neuronal transmission that modulates the S/N in neuronal circuits. The model uses the biologically relevant computer model of the CA3 region of the hippocampus developed in the companion paper [Moxon et al. (2003) Biol Cybern, this volume]. Modified Hebb cell assemblies represented the response of the network to the click stimulus. The results of our model showed that excessive dopaminergic input impaired the ability of cells to respond synchronously to sensory input, which reduced the amplitudes of the P50 evoked responses. Received: 3 December 2001 / Accepted: 23 October 2002 / Published online: 28 February 2003 Correspondence to: K.A. Moxon (e-mail: karen.moxon@drexel.edu, Tel.: +1-215-8951959, Fax: +1-215-8954983) Supported by USPHS, MH01245 & MH58414, MH-01121, and research grants from the Department of Veterans Affairs and the National Alliance for Research on Schizophrenia and Depression.     

锯缘青蟹视网膜电图特性的昼夜节律变化

本文系统地分析了锯缘青蟹scylla serrata视网膜电图特性(敏感度、光谱敏感性和波形)的昼夜节律性变化。这种节律性可能主要是由于视网膜屏蔽色素位置的昼夜变化所致,但也可能存在另一种机制。     

耳蜗电位的持续反应与其中单个脉冲的反应

研究了豚鼠耳蜗电位中持续反应与其中的单个脉冲反应的关系。由于听学系统存在着非线性,因此仅仅知道由单个短声诱发的耳蜗电位脉冲反应还无法预测一串等间隔重复短声诱发的持续反应。然而,等间隔重复短声串中第5个以后的每个短声受前面所有短声的掩蔽都相同,诱发的反应都相同,因此持续反应的稳态部分可以由掩蔽作用达到饱和时单个短声的反应通过延时相加得到。本文在时间域和频率域上定量地证明了这点。     

听觉诱发电位早成分中掩蔽作用与刺激参数之间的关系

本文研究了用短声串作为刺激时,其中每个短声所诱发的反应所受到的掩蔽作用与其前短声的个数、间距以及强度之间的关系.实验表明,个数越多,掩蔽作用越强,但当个数大到一定数目时,所受掩蔽作用渐趋饱和,不再随个数的增大而增大;间距越小,掩蔽作用越强;强度越大,掩蔽作用也越强     

Long latency auditory evoked potentials: intensity, inter-stimulus interval, and habituation

Experiment 1 elicited the P1, N1, P2, and N2 components of the long latency auditory evoked potential (AEP) using a 1000 Hz tone presented at 30, 50, or 70 dB SPL and 1-, 3-, or 5-second inter-stimulus intervals to assess the relative effects of the combination of these variables on component amplitude and latency. Four blocks of 16 tone presentations each were recorded from each subject to determine if changes in the AEP would occur because of short-term habituation. Both stimulus factors interacted significantly in a systematic fashion for the amplitude measures, with increases in latency also associated with increases in intensity and inter-stimulus interval. Only minor changes across the four trial blocks for either the amplitude or latency measures were observed over the various stimulus presentation conditions. Experiment 2 employed the same tone stimulus presented at 50 dB SPL and a 3-second inter-stimulus interval. Eight blocks of 64 trials were recorded from each subject on each day for four days to investigate long-term habituation effects. No substantial changes in any of the component amplitudes or latencies were obtained across the 32 trial blocks. It was concluded that intensity and inter-stimulus interval interact to determine AEP amplitude as well as latency values and that the constituent components do not change appreciably with repeated stimulus presentations, even after several days.     

The 3-channel Lissajous' trajectory of the auditory brain-stem response. V. Effects of stimulus intensity in the cat

Three-channel Lissajous' trajectories (3-CLTs) of the cat auditory brain-stem response (ABR) were recorded using click stimuli ranging from 10 to 70 dB impulse SPL and were analyzed using planar analysis.The number of planar segments increased from typically 4 at 10 dB to 12 at 70 dB but certain shape features of the 3-CLT (apices) were preserved across stimulus levels. As stimulus level was raised, size of individual planar segments increased. There were progressive decreases in apex latency as stimulus level was increased. The combined durations of groups of high intensity planar segments were similar to those of their low intensity forms. Shape, size and orientation of planar segments tended to change more across stimulus intensities below 40 dB than above and appear to relate to the number of planar segments at any given stimulus level.These results suggest that changes in latency seem to be primarily cochlear in origin, whereas the origin of other observed changes is uncertain. The 3-CLT ABR is sensitive to intensity, especially below 40 dB, and can thus detect changes in auditory system function in response to changes in stimulus intensity, regardless of electrode position.     

强声对豚鼠动作电位（N_1）潜伏期的影响及永久性阈移（PTS）早期预测指标分析

用慢性面神经管长期置入电极方法,测试了不同时间,不同强度的白噪声或２．８３ＫＨｚ强纯音暴露下清醒豚鼠的ＡＰ（Ｎ１）潜伏期。结果发现,暴露后对短声及各频率短纯音反应的ＡＰ（Ｎ１）潜伏期均出现统计学意义的延长者,可作为预测永久性阈移（ＰＴＳ）的一项较理想的指标。     

强声对豚鼠动作电位（N_1）潜伏期的影响及永久性阈移（PTS）早期预测指标分析

用慢性面神经管长期置入电极方法,测试了不同时间,不同强度的白噪声或２．８３ＫＨｚ,强纯音暴露下清醒豚鼠的ＡＰ（Ｎ１）潜伏期,结果发现,暴露后对短声及各频率短纯音反应的ＡＰ（Ｎ１）潜伏期均出现统计学意义的延长者,可作为预测永久性阈移（ＰＴＳ）的一项较理想的指标。     

Analysis of variance delimitation of factors influencing studies of acoustic evoked potentials]

The effect of the variables "stimulus intensity", "residual effect of previous stimulus intensity", "period effect" and "subject effect" on the amplitudes and on the peak latencies of the N1 and P1 components of the acoustical EEG evoked potentials was studied in human subjects with the use of an orthogonal experimental design. The stimulus intensity (30, 50 and 80 dB) accounts for the greatest part of the total variance of the amplitudes and of the peak latencies of N1.-The existence of a totalvariance component due to differences between the subjects is also statistically significant (P equals 5%), As far as the period effect (habituation effect) is concerned, only its effect on the amplitude of N1 - P2 is statistically significant. - The residual effect of the stimulus intensity used in the previous series was not significant.