Development of the place principle: acoustic trauma

Developmental changes in the site of receptor damage following pure-tone acoustic overstimulation were examined in the basilar papillae of embryonic and hatchling chickens. During development, a systematic shift in the position of damage toward the apex of the cochlea was produced by each of three frequencies, suggesting that the transduction properties of the sensory epithelium systematically shift with age. These results imply that neurons in the central nervous system may be maximally stimulated by different sounds during development.     

Auditory responses in avian vocal motor neurons: a motor theory for song perception in birds

The hypoglossal motor neurons that innervate the vocal organ (syrinx) of the male zebra finch show a selective, long-latency (50-millisecond) response to sound. This response is eliminated by lesions to forebrain song-control nuclei. Different song syllables elicit a response from different syringeal motor neurons. Conspecific vocalizations may therefore be perceived as members of a set of vocal gestures and thus distinct from other environmental sounds. This hypothesis is an avian parallel to the motor theory of speech perception in humans.     

Frequency sensitivity of single auditory neurons in the gecko Coleonyx variegatus

Although acoustic communication is not pronounced in reptiles, analysis of single auditory neurons in the medulla oblongata shows that the cochlea is a frequency analyser. Auditory neurons of the lizard Coleonyx variegatus respond to acoustic stimuli over a range of less than 0.1 to 17 kilohertz and are maximally responsive between 0.8 and 2.0 kilohertz. The frequencies to which they are most sensitive differ from neuron to neuron, ranging from 0.11 to 4 kilohertz. Some neurons have an inhibitory area which greatly overlaps the response area, so that inhibitory areas do not seem to sharply tune the response area at this level of the auditory tract. The inhibitory area is responsible for producing in some neurons a phasic response and nonmonotonic relation between sound intensity and number of impulses. The response pattern shows a tendency to change from tonic to phasic in more advanced auditory centers. This may serve to code rapid changes in the acoustic stimuli.     

Contrast tuning in auditory cortex

The acoustic features useful for converting auditory information into perceived objects are poorly understood. Although auditory cortex neurons have been described as being narrowly tuned and preferentially responsive to narrowband signals, naturally occurring sounds are generally wideband with unique spectral energy profiles. Through the use of parametric wideband acoustic stimuli, we found that such neurons in awake marmoset monkeys respond vigorously to wideband sounds having complex spectral shapes, preferring stimuli of either high or low spectral contrast. Low contrast-preferring neurons cannot be studied thoroughly with narrowband stimuli and have not been previously described. These findings indicate that spectral contrast reflects an important stimulus decomposition in auditory cortex and may contribute to the recognition of acoustic objects.     

Neural attenuation of responses to emitted sounds in echolocating rats

Bats of the family Vespertilionidae enmit strong ultrasonic pulses for echolocation. If such sounds directly stimulate their ears, the detection of echoes from short distances would be impaired. The responses of lateral lemniscal neurons to emitted sounds were found to be much smaller than those to playback sounds, even when the response of the auditory nerve was the same to both types of sounds. Thus, responses to self-vocalized sounds were attenuated between the cochlear nerve and the inferior colliculus. The mean attenuation was 25 decibels. This neural attenuating mechanism is probably a part of the mechanisms for effective echo detection.     

Identification and characterization of a neuron-specific nuclear antigen in Drosophila

An antigen found only in neuronal nuclei of Drosophila melanogaster is revealed by staining with a monoclonal antibody (Mab44C11). This antigen appears early in development, before neurons show any other signs of antigenic or morphologic differentiation, and persists throughout development. This nuclear staining permits reliable detection of neurons in developmental studies of wild-type and mutant flies. Protein immunoblot analyses and immune precipitation experiments show that the neuronal nuclear antigen is a 50-kilodalton polypeptide.     

Sharks: Attraction by Low-Frequency Sounds

Large sharks (Carcharhinidae, Sphyrnidae), in their natural environment, were attracted to low-frequency (predominantly 20 to 60 cy/sec) pulsed sounds, but apparently not to higher frequency (400 to 600 cy/sec) pulsed sounds, or to low-frequency continuous sounds. The sharks apparently detected and oriented to the sounds in the acoustic far field.     

Ventral posterior thalamic neurons differentially responsive to noxious stimulation of the awake monkey

Of 76 cutaneously activated neurons recorded from the ventral posterior thalamus of awake, behaving monkeys, nine were weakly excited by innocuous skin stimulation and responded maximally only when noxious mechanical cutaneous stimuli were delivered within small, contralateral receptive fields. These results show that neurons capable of encoding the spatial and temporal features of noxious stimuli are located in the ventral posterior thalamus of the awake primate.     

Functional specialization in rhesus monkey auditory cortex

Neurons in the lateral belt areas of rhesus monkey auditory cortex prefer complex sounds to pure tones, but functional specializations of these multiple maps in the superior temporal region have not been determined. We tested the specificity of neurons in the lateral belt with species-specific communication calls presented at different azimuth positions. We found that neurons in the anterior belt are more selective for the type of call, whereas neurons in the caudal belt consistently show the greatest spatial selectivity. These results suggest that cortical processing of auditory spatial and pattern information is performed in specialized streams rather than one homogeneously distributed system.     

Real-time recognition of sick pig cough sounds

This paper extends existing cough identification methods and proposes a real-time method for identifying sick pig cough sounds. The analysis and classification is based on the frequency domain characteristics of the signal, while an improved procedure to extract the reference is presented. This technique evaluates fuzzy c-means clustering to parts of the training signals and provides a frequency content reference that mirrors the characteristics of sick pig cough. The extraction of the reference is performed in such a way that allows for the identification process to be implemented in real-time applications that would speed up the diagnosis and treatment process and improve animal welfare in pig houses. Preliminary results for the evaluation of the algorithm are based on individual sounds of healthy and sick animals acquired in laboratory conditions. An 85% overall correct classification ratio is achieved with 82% of the sick cough sounds being correctly identified.     

支配山羊胸腺的神经纤维起源

用ＨＲＰ法研究证明,支配山羊胸腺的初级传入神经来源于双侧Ｃ１～Ｔ５ 脊神经节,以同侧为主;其标记神经元的分布呈双峰型;在双侧结状节也出现少量标记细胞,山羊胸腺的感觉经两侧神经传入,以交感途径占优势;交感节后纤维来自双侧颈前节、颈中节、星状节及Ｔ２～Ｔ５ 椎旁节,其中颈中节和星状节的标记细胞最多;在双侧Ｃ１～２节脊髓腹角和延髓疑核出现标记细胞较多,延髓迷走神经背核、面后核和脊上核出现较少的标记细胞。     

北京鸭脑内蓝斑的解剖

在光镜下观察北京鸭脑的连续切片。并将 HRP 注入食管、胃、心脏和脊髓,逆向追踪迷走神经背核传出神经元在核内的定位。北京鸭迷走神经背核位于延髓呈纵向细胞柱,可明显地分为背侧部和腹侧部。腹侧部含淡染小细胞,多为梭形,细胞直径18～20 μm。背侧部内含中小型细胞,混合排列,直径20～35 μm;在闩前的后段还出现大细胞,直径35～40 μm。在二部的外侧有一小部为外侧部。本文提出按部位划分亚核的原则以利应用。共分为尾侧亚核、吻侧亚核、闩前背侧后核、闩前腹侧后核、闩前外侧后核、闩前背侧前核、闩前腹侧前核、闩前外侧前核共8个亚核。用 HRP 法追踪投射到食管各段、腺胃和肌胃薄肌与厚肌、心脏以及脊髓的神经元,肯定了北京鸭迷走神经背核投射至以上各外周器官的神经元在核内有一定的定位区域。     

Aplysia californica: analysis of nuclear DNA in individual nuclei of giant neurons

The nuclei of the giant neurons of the marine mollusk Aplysia californica can contain more than 0.2 microgram of DNA. This is more than 200,000 times as much DNA as the haploid amount found in Aplysia sperm. On the basis of nuclear DNA content, the giant neurons R-2, P-1, and L-6 of adult animals can each be divided into at least two populations. The mean DNA content of these two populations (0.067 and 0.131 microgram of DNA) are approximately related by a factor of 2. This suggests that much and perhaps all of the genome replicates repeatedly (up to 16 times) during the growth and development of these neurons and that each replication is synchronous. The enormous amount of DNA in these cells opens up the possibility of characterizing the DNA and other constituents of chromatin from individual but phenotypically different neurons.     

Aeroelastic flutter produces hummingbird feather songs

During courtship flights, males of some hummingbird species produce diverse sounds with tail feathers of varying shapes. We show that these sounds are produced by air flowing past a feather, causing it to aeroelastically flutter and generate flutter-induced sound. Scanning laser doppler vibrometery and high-speed video of individual feathers of different sizes and shapes in a wind tunnel revealed multiple vibratory modes that produce a range of acoustic frequencies and harmonic structures. Neighboring feathers can be aerodynamically coupled and flutter either at the same frequency, resulting in sympathetic vibrations that increase loudness, or at different frequencies, resulting in audible interaction frequencies. Aeroelastic flutter is intrinsic to stiff airfoils such as feathers and thus explains tonal sounds that are common in bird flight.     

Glutamate, the dominant excitatory transmitter in neuroendocrine regulation

Glutamate has been found to play an unexpectedly important role in neuroendocrine regulation in the hypothalamus, as revealed in converging experiments with ultrastructural immunocytochemistry, optical physiology with a calcium-sensitive dye, and intracellular electrical recording. There were large amounts of glutamate in boutons making synaptic contact with neuroendocrine neurons in the arcuate, paraventricular, and supraoptic nuclei. Almost all medial hypothalamic neurons responded to glutamate and to the glutamate agonists quisqualate and kainate with a consistent increase in intracellular calcium. In all magnocellular and parvocellular neurons of the paraventricular and arcuate nuclei tested, the non-NMDA (non-N-methyl-D-aspartate) glutamate antagonist CNQX (cyano-2,3-dihydroxy-7-nitroquinoxaline) reduced electrically stimulated and spontaneous excitatory postsynaptic potentials, suggesting that the endogenous neurotransmitter is an excitatory amino acid acting primarily on non-NMDA receptors. These results indicate that glutamate plays a major, widespread role in the control of neuroendocrine neurons.     

Echo-ranging neurons in the inferior colliculus of bats

Bats measure the distance to an object in terms of the time lag between their outgoing orientation sounds and the returning echo. For measurement of the time lag, the latency of response of a neuron to a stimulus must be nearly constant regardless of the stimulus amplitude and envelope. Otherwise, a large error would be introduced into the measurement. Bats have neurons that are specialized for echo ranging.     

6种家禽孤束核的脊髓通路：HRP逆行追踪法研究

应用微电泳逆行追踪技术，分别向北京鸭，麻鸭，鹅、鸡、鸽和鹌鹑脊髓的颈、胸、腰段的一侧灰质中导入辣根过氧化物酶系统地研究了其孤束核至脊髓传导通路和细胞构筑。结果如下：在颈髓不同节段单侧灰质导入Ｈ ＲＰ后，６种家禽延髓的双侧孤束核内都出现了大量的标准细胞；     

Estradiol is concentrated in tyrosine hydroxylase-containing neurons of the hypothalamus

Localization of [3H]estradiol in tyrosine hydroxylase-containing neurons of rat brain was shown by a combined technique of autoradiography and immunohistochemistry. [3H]Estradiol was concentrated in the nuclei of tyrosine hydroxylase-containing neurons in the nucleus arcuatus, nucleus periventricularis hypothalami, and the zona incerta. These results suggest that estradiol acts directly on dopamine-producing neurons of the tuberoinfundibular system and incertohypothalamic system.     

褐菖鲉发声系统形态结构及其发声特征研究

分别采用形态学和模拟领地入侵的方法研究了褐菖鲉发声系统和发声特征。结果表明,褐菖鲉发声系统由鱼鳔肌和鱼鳔组成。鱼鳔肌前方附着于颅骨的翼耳骨,后经第1～7肋骨,与鱼鳔背后侧部相连。在领地入侵模拟实验中,褐菖鲉发出了连续脉冲的“咕噜噜”声音,其平均脉冲周期为(32.6±2.6) ms,平均脉冲间隔为(51.8±81.4) ms, 主频为68～175 Hz。对单个声音脉冲中包涵的正弦波型的能量周期分析发现：其声音主频与最大能量周期的倒数一致,表明褐菖鲉是采用鱼鳔肌收缩的发声机制。     

家禽动眼神经副交感核和Cajal中介核至脊髓的直接投射——HRP法研究

采用微电泳导入法和微量注射法,将HRP分别引入脊髓的颈中部、颈膨大部和腰膨大部,逆行追踪了北京鸭、麻鸭、鹅、鸡、鸽子和鹌鹑6种家禽的上位神经元。结果发现：大量标记细胞不仅分布于中脑对侧红核,还分布于双侧的动眼神经副交感核（EW核）,Cajal中介核和中央灰质,少量标记细胞分布于中脑网状结构和中缝核。标记细胞分布数量的规律是：颈中部引入HRP后,出现的标记细胞最多;颈膨大部引入HRP者次之;腰膨大部引入HRP后,出现的标记细胞最少。两种方法的实验结果没有明显的差异。6种动物之间的差异也不显著。各组实验中,在中脑的顶盖没有任何部位出现标记细胞。研究结果表明：家禽的中脑脊髓通路中,除了具有红核脊髓束、网状脊髓束和中缝脊髓束外,还存在着EW核至脊髓的直接传导通路和Cajal中介核至脊髓的直接传导通路。