Characteristics of electrical responses by the medial geniculate bodies in Vespertilionidae and Rhinolophidae to ultrasonic stimuli with different frequencies

The total electrical responses and action potentials of the neurons in the medial geniculate bodies in Vespertilionidae and Rhinolophidae were investigated. Maximum sensitivity to ultrasonic stimuli was recorded inMyotis oxygnathus (Vespertilionidae) in the range 10–40 kc/sec and 65–80 kc/sec, and in Rhinolophidae in the ranges 10–70 kc/sec and 81–86 kc/sec. Low thresholds were observed inMyotis oxygnathus for the frequencies covered by their echo-location cries, whereas the thresholds recorded in Rhinolophidae in the 80 kc/sec band (the principal frequency of their echo location cries) were 15–30 dB higher than those for adjacent frequencies. Minimum thresholds of off-responses were observed inMyotis oxygnathus in the range 50–60 kc/sec, and in Rhinolophidae in the range 78–80 kc/sec. The regions of neuronal response in both species of bat were generally similar in form to those of responses recorded in the medial geniculate bodies of other mammals. Some of the neurons in Rhinolophidae with a characteristic frequency of about 80 kc/sec were also sensitive to stimuli with one-half and one-third of the principal frequency. In Rhinolophidae the greatest selectivity for frequencies was possessed by neurons that responded within the range from 80 to 90 kc/sec.A. A. Zhadanov Leningrad State University. Translated from Neirofiziologiya, Vol. 3, No. 2, pp. 138–144, March–April, 1971.     

Sharply tuned cochlear nerve ensemble periodicity responses to sonic and ultrasonic frequencies

Vertebrates are able to perceive the pitch of a series of harmonics, even when the fundamental frequency has been removed from the acoustic stimulus. Neural periodicity responses corresponding to the “missing fundamental” frequency of sonic stimuli have been observed in the auditory system of several animal species, including our own. This paper examines periodic cochlear neural responses of the gerbil. Periodicity responses to both sonic and ultrasonic stimuli originate within the cochlea of this animal. Acoustic stimuli, consisting of 2–12 successive harmonic frequencies, were used to generate an ensemble cochlear nerve periodicity response that was recorded from the round window of the cochlea. This response had a frequency equal to that of the missing fundamental, and not to those of the harmonic stimuli. Forward masking of the stimuli used to produce the periodicity response was used to generate sharp tuning curves, with tip frequencies corresponding to the harmonics and not to the periodicities. The sharpness of these functions increased as the frequencies of the harmonics increased, up to at least 38 kHz. This property could be related to reception of ultrasonic vocalizations utilized by many rodent species. Accepted: 11 April 1997     

Characteristics of electrical responses by cochlear nuclei in Vespertilionidae and Rhinolophidae to ultrasonic stimuli with various fill frequencies

The total electrical response and action potentials of separate neurons in the cochlear nuclei in Vespertilionidae and Rhinolophidae were investigated. Maximum sensitivity to ultrasound was recorded in Vespertilionidae in the frequency ranges 10–30 and 70–80 kc/sec, and in Rhinolophidae in the frequency ranges 10–30 and 84–86 kc/sec. Mininum off-response thresholds were observed in Vespertilionidae in the range 50–60 kc/sec, and in Rhinolophidae in the range 78–80 kc/sec. The areas of responses by neurons in the cochlear nuclei in both species of bats were similar in shape to those recorded in the same structure in other animals. An exception was provided by Rhinolophidae, in which three peculiar types of neurons were observed: 1) neurons whose response area lay in the frequency ranges up to 78 kc/sec or from 80 to 90 kc/sec; 2) neurons responding in the range 40–90 kc/sec, but not sensitive to stimuli with a fill frequency of 78–80 kc/sec; and 3) neurons whose response area lay in the range 78–80 kc/sec, but in which the character of the response changed from tonic to phasic when there was a change in the fill frequency of the stimulus. Maximum selectivity with regard to fill frequency of stimulus was observed in the neurons of Rhinolophidae in the frequency range 70–90 kc/sec.The term "fill frequency" can be rendered as frequency — Consultants Bureau.A. A. Zhdanov Leningrad State University. Translated from Neirofiziologiya, Vol. 3, No. 4, pp. 379–385, July–August, 1971.     

Frequency following response to cochlear nuclei in cats to polycomponent sonic signals]

Under chloralose-urethane anaesthesia, by means of spectrograms and dynamic spectrograms studies have been made on frequency following response (FFR) in the cochlear nuclei of cats evoked by sonic stimulation. It was shown that FFR readily reproduces frequencies of the acoustic spectrum of separate tones and two-tonal harmonic complexes (the upper reproduced frequency in FFR - 6.0-6.5 kc/sec). The main deteils of the acoustic spectrum of the sounds of speech are also easily reproduced in FFR. Combination tones were observed in FFR during application of two-tonal harmonic complexes. The first harmonic is inhibited in FFR when combined with higher ones (the fifth or the sixth) or at certain phase angle between the first and the second harmonics ("doubling" phenomenon).     

Auditory responses in the torus semicircularis of the cane toad, Bufo marinus. I. Field potential studies

Field potentials have been recorded in the torus semicircularis of the toad, Bufo marinus, in response to brief tones presented in the free field. The amplitude of the potentials varied with the frequency of the stimulus and location of the electrode along the rostro-caudal axis of the torus. All frequencies in the auditory range evoked largest potentials when the stimulus was located in the contralateral auditory field. Potentials evoked by low to mid frequencies were largest when the stimulus was located near the line orthogonal to the long axis of the animal. For progressively higher frequencies, the optimal stimulus position was progressively more anterior in the contralateral field. In animals in which one eighth nerve had been sectioned, field potentials evoked by tones of low to mid frequency were less sensitive to changes in stimulus direction than in normal animals. However, the directional sensitivity of field potentials evoked by mid to high frequencies was similar in monaural and normal animals. These observations suggest that binaural neural integration is important in determining the directional sensitivity of field potentials in the torus evoked by low to mid frequencies but not for potentials evoked by mid to high frequencies.     

Sterilizing Effects of High-Intensity Airborne Sonic and Ultrasonic Waves

The lethal effects of high-intensity airborne sonic (9.9 kc/sec) and ultrasonic waves (30.4 kc/sec) on spores of Bacillus subtilis var. niger ATCC 9372 were determined. The spores, which were deposited on filter-paper strips, were exposed to sound waves for periods varying from 1 to 8 hr, at a temperature of 40 C and a relative humidity of 40%. Significant reductions in the viable counts of spores exposed to airborne sonic or ultrasonic irradiations were obtained. The antibacterial activity of airborne sound waves varied with the sound intensity level, the period of irradiation, and the distance of the sample from the sound source. At similar intensity levels, the amplitude of motion of the sound waves appeared to be a factor in acoustic sterilization.     

Brain-stem auditory evoked potentials in the common marmoset (Callithrix jacchus)

Brain-stem auditory evoked potentials (BAEPs) were recorded in 10 common marmosets (Callithrix jacchus) to investigate the effects of recording electrode configurations, stimulus rate, and stimulus frequency on BAEP wave forms and peak latencies. Tone burst stimulations were used to evaluate the effects of pure tone on BAEP wave forms. Five positive peaks superimposed on positive and negative slow potentials were identified in the BAEP recorded at the linkage between the vertex and the dorsal base of the ear ipsilateral to a monaural stimulus. When the reference electrode was placed at the ipsilateral mastoid or the neck, the amplitudes of positive and negative slow potentials and the incidence of wave I increased. There were no significant changes in peak latencies of BAEP waves with changes in stimulus rate from 5 to 20/s. It was possible to record the BAEPs in response to tone burst stimulations at frequencies extending from 0.5 to 99 kHz. Wave I appeared apparently at high stimulus frequencies; while waves III to V, at low frequencies. Wave II was recorded at frequencies ranging from 0.5 to 99 kHz and comprised a superposition of 2 or 3 potentials.     

"Resonance-like" frequencies of sensorimotor areas evoked by repetitive tactile stimulation.

The aim of the present study was to investigate resonance-like frequencies of somatosensory steady-state evoked potentials (SSSEPs) during mechanical stimulation of the left and right index finger. The resonance effects were studied in a group of normal subjects at 8 frequencies between 17 Hz and 31 Hz. Band power was computed in 2 s epochs in eight 2 Hz beta bands starting from 16-18 Hz up to 30-32 Hz and referred to a baseline prior to stimulation. For each subject the band with the largest band power increase was determined on electrodes overlying the contralateral hand area. The band power maxima and therewith the "resonance-like" frequencies were found around 27 Hz.     

加拿大披碱草、老芒麦及其杂种F1代的RAPD分析

加拿大披碱草和老芒麦是披碱草属地理性远缘的2个种。采用RAPD技术,筛选了16个随机引物对这2个种及其F1代进行遗传多态性检测。在获得的186个位点中,114个为多念性位点,占61．29％。从种群内的遗传多态性来看,加拿大披碱草的多态性位点百分率最高(242．04%),其次是老芒麦(9．14%),杂种F1(1．61％)。从种群间的遗传关系来看,加拿大披碱草和老芒麦的遗传距离为0．4979,杂种F1与母本加拿大披碱草的遗传距离(0．2720)较近,而与父本老芒麦的遗传距离(0.4074)相对较远。     

Posttetanic changes in hippocampal minimal evoked potentials

Changes in the EEG induced by a single spike were recorded in the hippocampus of an unanesthetized rabbit. Summation of focal electrical activity synchronous with spontaneous single unit discharges at the symmetrical point of contralateral hemisphere revealed no stable potentials which could reflect these changes. In two cases discharges identified as activity of Shaffer's collaterals were recorded in area CA₁. Summation of post-spike changes in evoked activity recorded by the same microelectrode showed stable negative waves with an amplitute of 40–60 µV, which could have been evoked by single spikes. The curve of amplitude of the averaged evoked potentials versus near-threshold current strength stimulating the intrahippocampal pathways was not smooth in most experiments but stepwise in character. It is suggested that the minimal evoked potential corresponding to the first step (amplitude 40–80 µV) reflects a response to stimulation of one fiber. After above-threshold tetanization prolonged posttetanic potentiation of the minimal evoked potentials did not arise in CA₁ in response to stimulation of Shaffer's collaterals. Minimal evoked potentials recorded in area CA₃ in response to stimulation of the dentate fascia showed clear potentiation. The results are in agreement with the hypothesis of the synaptic localization of the mechanisms responsible for prolonged posttetanic potentiation.Brain Institute, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 9, No. 2, pp. 124–134, March–April, 1977.     

Ontogenetic patterns of frequency-power spectra elicited by flickering light in children: a comparative study of evoked and background EEGs.

Frequency-power spectra of the EEG evoked by repeptitive photic stimulation and of the background EEG were studied during childhood in 43 awake subjects aged between 2 months and 14 years. EEG activity was recorded from the middle parieto-occipital region with the aid of a 1-channel analyzer Lysograf-Alvar, analysing 16 frequencies in the range from 2 to 28 c/sec. The responsiveness of the central nervous system to flickering light improved in the course of childhood in parallel with the significant decline of delta activity and with the prominent increase of alpha intensity in the resting EEG. The 4th month of life appeared to be a marked turning point in the development of evoked and background EEGs. From that age, the bioelectric power at the flash rate corresponding to photic "driving" began to increase together with the highest and optimal driving frequencies. The flash rate, at which evoked potentials changed into the "driven" rhythm, also shifted towards higher frequencies. Subsequently, the amount of energy in the resting EEG increased significantly within the theta, alpha and beta bands and, on the contrary, a prominent decline was observed in the delta range. Marked ontogenetic changes at this age closely coincided with the rapid development of exogenous fibres in the occipital cortex, including the thalamo-cortical conncetions, and fibres of the neuropil in cortical layer I, which might play an important role in the genesis of background and "driven" in the occipital region.     

意大利蝗和西伯利亚蝗高温耐受能力及酶活性比较研究

【目的】阐明意大利蝗Calliptamus italicus和西伯利亚蝗Gomphocerus sibiricus高温耐受能力及酶活性差异。【方法】以3℃为间隔,将意大利蝗和西伯利亚蝗成虫分别在27~48℃、24~42℃下处理4 h后测定死亡率及POD、SOD和CAT活性值。【结果】27~42℃处理下,意大利蝗存活率显著大于西伯利亚蝗(P<0.05)。雌性意大利蝗的LT50、LT90分别为48.76℃和50.67℃,雄虫则分别为47.90℃和50.53℃;雌性西伯利亚蝗的LT50、LT90分别为39.21℃和42.10℃,雄虫则分别为36.11℃和41.43℃。随着温度升高,雄性意大利蝗和雌、雄西伯利亚蝗体内POD、SOD、CAT活性先升高后降低,雌性意大利蝗体内POD活性则先降低后升高。27~42℃范围内,西伯利亚蝗体内POD和SOD活性值增幅较大,分别达到54.69%、23.54%;意大利蝗体内则以CAT活性值增幅最大,为27.02%。【结论】两种蝗虫耐高温能力存在差异,意大利蝗具有更强的耐热能力。     

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.     

Detection of low‐frequency tones and whale predator sounds by the American sand lance Ammodytes americanus

Auditory evoked potentials (AEP) were used to measure the hearing range and auditory sensitivity of the American sand lance Ammodytes americanus. Responses to amplitude‐modulated tone pips indicated that the hearing range extended from 50 to 400 Hz. Sound pressure thresholds were lowest between 200 and 400 Hz. Particle acceleration thresholds showed an improved sensitivity notch at 200 Hz but not substantial differences between frequencies and only a slight improvement in hearing abilities at lower frequencies. The hearing range was similar to Pacific sand lance Ammodytes personatus and variations between species may be due to differences in threshold evaluation methods. AEPs were also recorded in response to pulsed sounds simulating humpback whale Megaptera novaeangliae foraging vocalizations termed megapclicks. Responses were generated with pulses containing significant energy below 400 Hz. No responses were recorded using pulses with peak energy above 400 Hz. These results show that A. americanus can detect the particle motion component of low‐frequency tones and pulse sounds, including those similar to the low‐frequency components of megapclicks. Ammodytes americanus hearing may be used to detect environmental cues and the pulsed signals of mysticete predators.     

Chronic exposure of primates to 60-Hz electric and magnetic fields: III. Neurophysiologic effects

The neurophysiologic effects of combined 60-Hz electric (E) and magnetic (B) fields, of magnitudes comparable to those produced by high-voltage powerlines, were investigated in 10 monkeys (Macaca nemestrina). Six animals (experimental group) were each exposed to three different levels of E and B fields: 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G. Field exposures were preceded and followed by sham exposures, during which factors of field generation were present (e.g., heat, vibration, noise, etc.) without E and B fields. Each of the five segments (i.e., the three exposure segments and the initial and final sham exposure segments) lasted 3 weeks. Animals were exposed for 18 h/day (fields on at 1600 h, off at 1000 h). Four other animals (external control group) were given sham exposure for the entire 15-week period. Auditory, visual, and somatosensory evoked potentials were recorded twice a week, during the daily 6-h field-off period. E- and B-field exposure had no effect on the early or mid-latency evoked potential components, suggesting that exposure at these levels has no effect on peripheral or central sensory afferent pathways. However, there was a statistically significant decrease in the amplitudes of late components of the somatosensory evoked potential during the 10kV/m and 0.3 G, and 30 kV/m and 0.9 G exposure levels. This result is possibly related to the opiate antagonist effect of electromagnetic field exposure reported by others.     

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。     

Brain-stem evoked potentials and noise effects in seagulls

Brain-stem auditory evoked potentials (BAEP) recorded from the seagull were large-amplitude, short-latency, vertex-positive deflections which originate in the eighth nerve and several brain-stem nuclei. BAEP waveforms were similar in latency and configurations to that reported for certain other lower vertebrates and some mammals. BAEP recorded at several pure tone frequencies throughout the seagull's auditory spectrum showed an area of heightened auditory sensitivity between 1 and 3 kHz. This range was also found to be the primary bandwidth of the vocalization output of young seagulls. Masking by white noise and pure tones had remarkable effects on several parameters of the BAEP. In general, the tone- and click-induced BAEP were either reduced or obliterated by both pure tone and white noise maskers of specific signal to noise ratios and high intensity levels. The masking effects observed in this study may be related to the manner in which seagulls respond to intense environmental noise. One possible conclusion is that intense environmental noise, such as aircraft engine noise, may severely alter the seagull's localization apparatus and induce sonogenic stress, both of which could cause collisions with low-flying aircraft.     

Characteristics of evoked potentials and single neuron responses in the cat sensorimotor cortex to sound stimuli with different frequencies.

The characteristics of the averaged evoked potentials (AEP) (experiments with awake non-paralysed animals), of the evoked potentials (EP) and of the responses of single sensorimotor cortical neurons (acute experiments) of cats to tone-bursts with frequencies within 0.1-6.0 kHz were studied. Response selectivity to the tone-burst frequencies which are energetically pronounced in some biologically significant sounds for the cat was observed. The averaged curve of the dependence of the amplitude of AEP in the somatosensory cortical region (S1) on the tone-burst frequency has reliable maximum values at the frequencies of 0.8, 1.6 and 2.0-3.0 kHz. Most pronounced changes in the heart rhythm were observed within the tone-burst frequency ranges in which the AEP of the highest amplitudes were recorded. The amplitude of the AEP was found to increase during the conditioned reflex elaboration. The curve of the dependence of the probability of the EP occurrence on the frequency at equal sound pressure levels had maximum values at the frequencies of 1.6 and 3.2 kHz. The highest amplitude values of EP were found at frequencies of 0.8, 1.6 and 3.2 kHz. More than half of the recorded neurons revealed the lowest values of the response thresholds and the maximum values of the occurrence probability under suprathreshold stimulation at frequencies close to 0.8, 1.6, and 3.2 kHz. It is supposed that the above mentioned feature of the input frequency organization in sensorimotor cortex is connected with the selectivity as to the biological significance of acoustic stimuli.     

Evoked potentials in the frog medulla to electrical stimulation of the glossopharyngeal nerve

Evoked potentials in the frog medulla to stimulation of the glossopharyngeal nerve appear on the ipsilateral side in a zone of limited area. They are recorded at depths not exceeding 2000 µ. Depending on their form the surface evoked potentials are divided into two groups, negative and positive—negative, differing from each other in their parameters and properties. During insertion of the microelectrode the phase of the negative potential is changed. The principal slow components of the responses reflect postsynaptic processes. The first fast wave of the evoked potential is regarded as the presynaptic component. Differences in the properties of the evoked potential recorded at different points are determined by the neuromorphological heterogeneity of the structures of the primary center.     

Contrast transfer function of the visual system]

Visually evoked potentials were used to determine the spatial contrast response function of the visual system and the visual acuity of the pigeon. The spatial contrast response describes the relationship between the contrast in a pattern of vertical stripes, whose luminance is a function of position, and the amplitude of the visually evoked response at various spatial frequencies for a given temporal frequency (pattern reversal frequency); it indicates how particular spatial frequencies are attenuated in the visual system. The visually evoked responses were recorded using monopolar stainless steel electrodes inserted into the stratum griseum superficiale of the optic tectum; the depth of penetration was determined on the basis of a stereotactic atlas. The stimulus patterns were generated on a video monitor placed 75 cm in front of the animal's eye perpendicular to the optic axis. The spatial contrast response function measured at 10% contrast and 0.5 Hz reversal frequency shows a peak at a spatial frequency of 0.5 c/deg, corresponding to 1 degree of visual angle, and decreases progressively at higher spatial frequencies. The high-frequency limit (cut-off frequency) for resolution of sinusoidal gratings, estimated from the contrast response function, is 15.5 c/deg, corresponding to a visual acuity of 1.9 min of arc.