褐菖鲉的听觉阈值研究

利用听觉诱发电位记录技术研究了褐菖鲉(Sebasticus marmoratus)的听觉阈值。通过采用听觉生理系统记录和分析了8尾褐菖鲉对频率范围在100—1000 Hz的7种不同频率的声音刺激的诱发电位反应。结果表明, 褐菖鲉的听觉阈值在整体上随着频率增加而增加, 对100—300 Hz的低频声音信号敏感, 最敏感频率为150 Hz, 对应的听觉阈值为70 dB re 1 μPa。褐菖鲉的听觉敏感区间与其发声频率具有较高的匹配性, 表明其声讯交流的重要性。同时, 人为低频噪声可能对其声讯交流造成影响。     

硕螽(Deracantha onos)听觉中间神经元的声反应特征

本文报道了硕螽听通路单个听觉中间神经元的声反应特征。依据动作电位发放模式的不同,听觉中间神经元可分为两类,即紧张型与相位型。紧张型听觉中间神经元属于窄凋谐带神经元,敏感的频率范围8—18千赫,反应最佳频率在12千赫附近,与同种雄硕螽叫声的主能峰相匹配。相位型听觉中间神经元属于宽调谐带神经元,有二个敏感频率范围,分别为5—8千赫和12—18千赫。它们对声强度的编码方式也不一样:分别以动作电位的数目与反应潜伏期对声强编码。本文还讨论了不同类型听觉中间神经元的功能意义。     

菊头幅出生后下丘听神经元反应特性的演化

实验在出生后1周到6周的幼年和成年鲁氏菊头蝠(Rhinolophusrouxi)上进行。结果发现,出生第1周的动物下丘听神经元对超声刺激反应的最佳频率低,潜伏期长,阈值高。它们的平均值分别为:31.24±14.08千赫,16.56±3.83毫秒和74.24±6.22dB。同时,调谐曲线宽阔,Q10-dB值小,其均值为2.34±0.96。随着周令增长,上述特性逐渐改变。到第6周时,最佳频率的均值发展到70.16±19.16千赫,最佳频率分布峰值也移至75—85千赫的高频段,反应潜伏期均值降至8.12±1.86毫秒,阈值均值降至32.82±26.36dB,已出现相当多具有非常陡削调谐曲线的神精元,Q10-dB值在20以上者占到80％,有的高达100以上,已接近成年动物。     

菊头幅出生后下丘听神经元反应特性的演化

实验在出生后1周到6周的幼年和成年鲁氏菊头蝠(Rhinolophusrouxi)上进行。结果发现,出生第1周的动物下丘听神经元对超声刺激反应的最佳频率低,潜伏期长,阈值高。它们的平均值分别为:31.24±14.08千赫,16.56±3.83毫秒和74.24±6.22dB。同时,调谐曲线宽阔,Q10-dB值小,其均值为2.34±0.96。随着周令增长,上述特性逐渐改变。到第6周时,最佳频率的均值发展到70.16±19.16千赫,最佳频率分布峰值也移至75—85千赫的高频段,反应潜伏期均值降至8.12±1.86毫秒,阈值均值降至32.82±26.36dB,已出现相当多具有非常陡削调谐曲线的神精元,Q10-dB值在20以上者占到80％,有的高达100以上,已接近成年动物。     

单频刺激声稳态诱发反应的可靠性研究

目的:通过测试正常听力青年男女的听觉多频稳态诱发反应ASSR和单频刺激声稳态诱发反应探求单频刺激声稳态诱发反应的可靠性。方法:选取32名64耳听力正常的青年人作为受试者,对其进行纯音听阈、ASSR及四个0.5、1、2、4k Hz单频刺激声稳态诱发反应阈值测试,并记录0.5、1、2和4k Hz四个频率纯音阈值及ASSR及四个单频刺激声稳态诱发反应阈值。结果:ASSR在0.5、1、2和4k Hz四个频率的反应阈值与纯音听阈阈值相关性系数分别为0.64、0.81、0.79、0.85;0.5k Hz单频刺激声稳态诱发反应阈值与ASSR阈值具有明显统计学差异,其余3个单频刺激声稳态诱发反应阈值与ASSR阈值没有统计学差异,0.5k Hz单频刺激声稳态诱发反应阈值与纯音听阈阈值相关性系数为0.81。结论:ASSR阈值与纯音听阈具有较好的相关性,0.5k Hz单频刺激声稳态诱发反应可以提高0.5k Hz ASSR阈值与纯音听阈的相关性。     

猫皮层17区细胞对栅形视觉刺激反应的某些特性

1.用玻璃绝缘的钨丝电极作细胞外记录,研究不了麻醉猫视皮层17区单个细胞对栅形刺激反应的某些特点。先用光学投影仪在屏幕上投影各种图形以确定细胞感受野位置,并对该细胞感受野性质作一般观察。随后用以电视监示器改装的方波——正弦波栅形发生器提供刺激,研究此细胞的空间频率-反应特性及对比度-反应特性。 2.所有对正弦波栅形有反应和空间频率选择性的细胞同样对方波栅形也有反应和空间频率选择性。它们的最优频率一致。简单细胞的通频带比复杂细胞的略窄。 3.绝大多数细胞对方波栅形的反应都比对同样条件下的正弦栅形反应大(1.33∶1),对比阈值低。 4.记录到少数细胞(7/54,6个为复杂型,1个类型不明),其方波栅形的频率-反应曲线与正弦波栅形的比较,两种反应在低频端有更大的差别,当把栅形对比度降低为接近阈值水平时,这个差别显著变小.     

虎皮鹦鹉的振动敏感性研究

本文研究了虎皮鹦鹉对正弦振动的敏感性,旨在探索其腿部存在赫氏小体,和阐明其震前声反应与地面振动的关系提供依据,虎皮鹦鹉对５－８０Ｈｚ的正弦振动不敏感,振动位移约２００－５０μｍ才可能激起声行为反应,但对１００－２５０Ｈｚ的正弦振动具有显著的敏感性,反应阈值约１０－２μｍ,对１３０－１７０Ｈｚ和２００－２５０Ｈｚ阈值反应,约７０％的潜伏期分别为ＬＰ＜３０ｓ和ＬＰ＜１５ｓ。     

虎皮鹦鹉(Melopsittacus undulatfus)的振动敏感性研究

本文研究了虎皮鹦鹉对正弦振动的敏感性,旨在探索其腿部存在赫氏小体,和阐明其震前声行为反应与地面振动的关系提供依据。虎皮鹦鹉对５０－８０Ｈｚ的正弦振动不敏感,振动位移约２００－５０μｍ才可能激起声行为反应．但对１００－２５０Ｈｚ的正弦振动具有显著的敏感性,反应阈值约１０－２μｍ。对１３０－１７０Ｈｚ和２００－２５０Ｈｚ阈值反应,约７０％的潜伏期（ＬＰ）分别为ＬＰ＜３０５和ＬＰ＜１５ｓ。     

蝇髓部细胞的运动敏感性

用细胞外记录方法研究了蝇髓部细胞的运动敏感性.实验证明,在蝇髓部有运动敏感型细胞,它们的主要特点是对运动敏感,但不具有方向选择性.其主要性质如下:1.有些细胞对闪光刺激给出超极化反应,有些则为去极化反应;2.对运动反应,但不具有方向性;3.有些对大视场的运动敏感,有些则对小视场的运动敏感;4.反应幅度与图形运动速度有关;5.感受野为简单型,并且不很大.对于可能对应的算法进行了讨论.     

大鼠听神经单纤维的活动

本文以声压级(SP)的dB值为单位,用不同频率(从音频到超声)的声刺激,对大鼠听觉一级神经元325根单一纤维的活动进行了观察。结果表明:每一纤维都有自己的最佳频率和相应的最低阈值。测得最佳频率的最低值为0.58kHz,最高值为62.6kHz; 最低阈值为6dBSPL,其相应频率为27.49kHz;最敏感的频率范围在20—50kHz。频率-阈值曲线在比最佳频率高的一侧斜度陡峭,低的一侧倾斜缓慢。频率-阈值曲线的锐度若以Q值表示,它对最佳频率分布的回归曲线由最佳频率的低频向高频方向逐渐升高,且Q10,Q20,Q30,Q40,Q50,dB的回归曲线具有相似的倾斜度。绝大多数纤维都有自发放电。给最佳频率持续音作用时,随刺激强度的增强,放电速率增加,但到阈上30dB左右皆达饱和。由各频率的最低阈值绘成的听反应阈曲线与行为测听所得的听力曲线颇为近似。     

Spinal dorsal column afferent fiber composition in the pigeon: an electrophysiological investigation

Summary The spinal dorsal column of homing pigeons (Colomba livia) was investigated electrophysiologically by recording responses from individual afferent fibers at a high cervical level (segments C4-C5) to mechanical stimulation of wing skin and deep tissue. Of 157 afferent fibers 134 were cutaneous afferents. The remainder were afferents of deep receptors.Thirty of the cutaneous afferents were slowly adapting and 87 rapidly adapting (17 not identified). Rapidly adapting afferents were studied with regard to Pacinianlike characteristics (Herbst corpuscles in birds; vibration sensitive receptors). Of 43 rapidly adapting afferents 38 were classified as afferents of vibration sensitive Herbst corpuscles and 5 as non vibration sensitive rapidly adapting afferents; 44 afferents could not be studied sufficiently with regard to vibrational stimuli. The vibration sensitive Herbst corpuscle afferents had U-shaped vibrational tuning curves and responded best to vibration frequencies of 300 to 400 Hz. The 11 threshold for 300 Hz vibration ranged from 2 to 36 um. Herbst corpuscle afferents always showed strong phase coupling to the stimulus cycle.Afferents of deep receptors showed slowly adapting responses to firm pressure or movements of limbs and were classified as joint receptors. No muscle spindle afferents were encountered.Primary afferent fibers were identified in 89 cases (80 cutaneous and 9 deep), postsynaptic elements in 15 cases (11 cutaneous, 4 deep). Only slowly adapting responses were found in postsynaptic fibers.Abbreviations CV coefficient of variation - EI entrainment index - INTH interval histogram - PSTH peristimulus time histogram - RA rapidly adapting - SA slowly adapting     

Histological and electrophysiological investigations on the vibration-sensitive receptors (Herbst corpuscles) in the wing of the pigeon (Columba livia)

Summary The Herbst corpuscles (HCs) of the pigeon's wing were investigated both histologically and electrophysiologically. All HCs found in the wing were lamellated, basic type corpuscles without any specialized structures. Their lengths ranged from 67 to 853 m (mean = 310 m). Unexpected findings were their large number (about 1000 in the manual part of the wing), their irregular distribution and their preferred orientation (approximately parallel or at right angles to the primary feather follicles). The HCs were highly sensitive to vibrational stimuli applied to wing feathers. Their electrophysiological behaviour has the following characteristics: no spontaneous activity, phase-locked nerve impulses, a 11 stimulus-response relation up to at least 660 Hz at sufficiently high stimulus amplitudes, and a sensitivity to stimulus frequencies up to 1800 Hz. The best frequencies of 52 receptive units for which complete threshold curves were obtained lay between 100 and 900 Hz, 67% of the best frequencies were between 200 and 400 Hz. The threshold amplitudes at best frequency ranged from 0.5 to 150 m. Two virtually non-overlapping mechanosensitive areas on the wing were identified. One is a very narrow band along the frontal edge and the other covers a large area of the remaining wing. They correspond with the two branches of the radial nerve. The histological and electrophysiological findings suggest that the HCs are part of a vibrational sensory system that is principally involved in flight control. The actual aerodynamic state during flight could be detected by the frontal receptive area, and flight behaviour could be adjusted accordingly. The effectiveness of these corrective reactions would then be assessed on the basis of air current changes along the caudal wing edge by the caudal receptive area. Despite some physiological differences considerable similarities between HCs and Pacinian corpuscles support the hypothesis that they evolved from a unique ancestral lamellar receptor.Abbreviations HC(s) Herbst corpuscle(s) - PC(s) Pacinian corpuscle(s) All experiments were carried out at the Ruhr-Universität Bochum, Lehrstuhl für Allgemeine Zoologie     

Response characteristics of Herbst corpuscles in the interosseous region of the pigeon's hind limb

The Herbst corpuscle, found only in birds, is one of the morphologically distinct types of lamellated sensory nerve endings. Its response properties were studied electrophysiologically in anesthetized pigeons by recording from: (A) afferents emerging from single Herbst corpuscles located in the interosseous region of the shank, (B) from vibration-sensitive cells found in the dorsal root ganglia near the lumbosacral enlargement of the spinal cord, and (C) from nerve fibers dissected out of the sciatic nerve. Vibration-sensitive cells in the dorsal root ganglia and in sciatic nerve fibers exhibited properties that were very similar to those found at the Herbst corpuscle itself. All three recording approaches indicated that Herbst corpuscles are vibration-sensitive mechano-receptors with broad bandpass tuning curves. With all approaches, the lowest threshold always fell in the frequency range between 400 and 800 Hz. The value of the threshold, however, varied with the method, being as low as 0.08 m with method C and as high as 1 m with method A. Regardless of method, these neurons exhibited no spontaneous activity, and their firing displayed a special sensory coding pattern at high stimulus amplitude: the nerve impulses were phase locked to the stimulus cycle, exhibiting a 1:1 relationship with it up to a frequency of 500 Hz. Comparison of these data with prior behavioral data suggests that the Herbst corpuscle peripheral mechanoreceptors are part of a vibratory sensory system which acts as a warning device, given attentive behavior.Abbreviations AP action potential - INTH interspike interval histogram     

Vibrational sensitivity of the wing of the pigeon (Columba livia) — a study using heart rate conditioning

Summary The vibrational sensitivity of awake pigeons was tested with the heart rate conditioning method. This method proved to be a very sensitive instrument for the behavioural measurement of the pigeon's sensitivity to mechanical stimuli.Sine wave vibrational stimuli between 50 and 2000 Hz were applied to the 1st, 7th and 16th primary feathers of the wing. The resulting threshold curves were U- or V-shaped with 3 characteristics: (i) The frequency of best response was either 800 or 900 Hz. (ii) Within the broad frequency range of vibrational sensitivity (50 to 2000 Hz) the sensitivity was extremely high at the best frequency: threshold amplitudes lay between 0.5 and 0.09 m. (iii) The threshold curves showed very sharp tuning at best frequency with bandwidths between 0.3 and 0.7 octaves (measured at best frequency 10fold above threshold). The functional meaning of the characteristic vibrational sensitivity of the wing for flight control is discussed; it is interpreted as an adaptation to special situations occurring during flight.Abbreviations CR conditioned response - CS conditioned stimulus - ECG electrocardiogram - HC(s) Herbst corpuscle(s) - UCS unconditioned stimulus All experiments were carried out at the Ruhr-Universität Bochum, Lehrstuhl für Allgemeine Zoologie     

Constrained tibial vibration in mice: a method for studying the effects of vibrational loading of bone

Vibrational loading can stimulate the formation of new trabecular bone or maintain bone mass. Studies investigating vibrational loading have often used whole-body vibration (WBV) as their loading method. However, WBV has limitations in small animal studies because transmissibility of vibration is dependent on posture. In this study, we propose constrained tibial vibration (CTV) as an experimental method for vibrational loading of mice under controlled conditions. In CTV, the lower leg of an anesthetized mouse is subjected to vertical vibrational loading while supporting a mass. The setup approximates a one degree-of-freedom vibrational system. Accelerometers were used to measure transmissibility of vibration through the lower leg in CTV at frequencies from 20 Hz to 150 Hz. First, the frequency response of transmissibility was quantified in vivo, and dissections were performed to remove one component of the mouse leg (the knee joint, foot, or soft tissue) to investigate the contribution of each component to the frequency response of the intact leg. Next, a finite element (FE) model of a mouse tibia-fibula was used to estimate the deformation of the bone during CTV. Finally, strain gages were used to determine the dependence of bone strain on loading frequency. The in vivo mouse leg in the CTV system had a resonant frequency of 60 Hz for +/-0.5 G vibration (1.0 G peak to peak). Removing the foot caused the natural frequency of the system to shift from 60 Hz to 70 Hz, removing the soft tissue caused no change in natural frequency, and removing the knee changed the natural frequency from 60 Hz to 90 Hz. By using the FE model, maximum tensile and compressive strains during CTV were estimated to be on the cranial-medial and caudolateral surfaces of the tibia, respectively, and the peak transmissibility and peak cortical strain occurred at the same frequency. Strain gage data confirmed the relationship between peak transmissibility and peak bone strain indicated by the FE model, and showed that the maximum cyclic tibial strain during CTV of the intact leg was 330+/-82microepsilon and occurred at 60-70 Hz. This study presents a comprehensive mechanical analysis of CTV, a loading method for studying vibrational loading under controlled conditions. This model will be used in future in vivo studies and will potentially become an important tool for understanding the response of bone to vibrational loading.     

Response characteristics of vibration-sensitive neurons in the midbrain of the grassfrog,Rana temporaria

Summary European grassfrogs (Rana temporaria) were stimulated with pulsed sinusoidal, vertical vibrations (10–300 Hz) and the responses of 46 single midbrain neurons were recorded in awake, immobilized animals.Most units (40) had simple V-shaped excitatory vibrational tuning curves. The distribution of best frequencies (BF's) was bimodal with peaks at 10 and 100 Hz and the thresholds ranged from 0.02 to 1.28cm/s² at the BF.Twenty-three neurons showed phasic-tonic and 11 neurons phasic responses. The dynamic range of seismic intensity for most neurons was 20–30 dB.In contrast to the sharp phase-locking in peripheral vibration-sensitive fibers, no phase-locking to the sinusoidal wave-form was seen in the midbrain neurons. The midbrain cells did not respond at low stimulus intensities (below 0.01–0.02 cm/s²) where a clear synchronization response occurs in saccular fibers.Six midbrain neurons had more complex response characteristics expressed by inhibition of their spontaneous activity by vibration or by bi-and trimodal sensory sensitivities.In conclusion, the vibration sensitive cells in the midbrain of the grassfrog can encode the frequency, intensity, onset and cessation of vibration stimuli. Seismic stimuli probably play a role in communication and detection of predators and the vibration-sensitive midbrain neurons may be involved in the central processing of such behaviorally significant stimuli.Abbreviation BF best frequency     

A behavioral study of vibrational sensitivity in the pigeon (Columba livia)

Summary The pigeon (Columba livia) has a well-developed ability to detect weak vibrations. Using the method of heart-rate conditioning the vibrational sensitivity was determined for four pigeons at an error probability of P<0.025. The threshold-frequency relationships indicate that the greatest sensitivity to vibrational stimuli is found in the frequency range from 300 to 1,000 Hz with thresholds of about 0.1 m; lowest threshold is 0.04 m at 500 Hz (Fig. 4). Pigeons can respond not only to the frequency of a stimulus, but also to its intensity. The interval decrement (in %) of ECG is a positive correlative function of the stimulus intensity, the calculated values being approximately 4–5% per order of magnitude of the stimulus amplitude (in m) at best frequencies (Fig. 5). The value of vibration detection for birds is discussed.Abbreviation ECG electrocardiogram     

Neurophysiology of the vibration sense in locusts and bushcrickets: Response characteristics of single receptor units

The response characteristics of the vibration receptors in the legs of the migratory locust, Locusta migratoria, and the tettigoniid Decticus verrucivorus were investigated electro-physiologically by single cell recordings. The legs were stimulated by sinusoidal vibrations. There are four types of vibration receptor in each leg of Locusta and Decticus, which can be classified physiologically. One type—most probably campaniform sensilla—shows a phase-locked response to vibrations from 30 to 200 Hz, its threshold reflecting the displacement. A second type shows similar responses in the same frequency range, but its reactions depend on the stimulus acceleration. The receptor cells of the subgenual organ are very sensitive to vibration from 30 to at least 5000 Hz, and their responses depend on acceleration. There are two types of subgenual receptors, one of which shows a clear maximum of sensitivity between 200 and 1000 Hz, with a threshold below 0.01 m/sec^?2 acceleration. Subgenual receptors with different thresholds and different characteristic frequencies occur in each leg. The receptors of each leg pair have quite similar mean sensitivities and characteristic frequencies. However, in the front legs of tettigoniids the more sensitive subgenual receptors and an additional receptor type also respond to low-frequency airborne sound up to 10 kHz.     

Analysis of the interference electromyogram of the human soleus muscle under vibrational stimulation

The characteristics of EMG structure are studied for the voluntarily contracting human m. soleus against the background of vibrational stimulation. Averaging over the vibration cycle and spectral analysis are used. Averaging reveals EMG nonuniformity over the cycle; narrow peaks appear in the spectrum at the vibration frequency. EMG analysis proves informative at high vibration frequencies (70–120 Hz), while analysis of the rectified EMG proves informative at low frequencies (30–70 Hz). In the case of tibial ischemic blockade the peak disappears earlier than the tendon reflex. As the force increases, the peak amplitude normalized to the EMG power decreases. The peak rises with prolonged contraction under vibration. These effects are thought to reflect the changes in the relative contribution to the stimulating influx to the motoneurons of the part which is delivered via short connections from the muscle receptors.Institute for Problems of Information Transmission, Acdemy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 23, No. 1, pp. 57–65, January–February, 1991.     

Frequency modulation of theta volleys of septal neurons during rhythmic oligosynaptic stimulation in the rabbit

Activity of the neurones with stable theta-bursts was recorded extracellularly in intact and hippocampectomized septum of unanaesthetized chronic rabbits during low-frequency (3-17 Hz) stimulation of horizontal limb of the diagonal band or the lateral septal nucleus. Gradual entrainment and phase-locking of the spontaneous theta-cycles occurred. Two types of entrainment were observed: "entrainment by pause", where interburst interval was reset by the stimuli; and "entrainment by burst", where bursts were time-locked to the stimuli. Such reorganization of the spontaneous bursts occurred in a narrow frequency range of stimulation (from 4 Hz up to 9-12 Hz), with the best resonance following in the range of "basic" theta frequencies of the awake rabbit (5-6 Hz). With stimulation beyond the theta-range three phenomena occurred: shift of the burst frequencies to higher or lower harmonics of stimulation frequencies; complex interactions of basic background frequency with the rhythm of stimulation ("beating"); escape from the influence of the stimuli with return to background theta-burst frequency.