Conjugation of unit activity in the visual and sensomotor areas of the rabbit neocortex during a conditioned reflex to sound and light

Conjugation of unit activity in the visual and sensorimotor neocortical areas was studied by means of histograms of cross- and autocorrelation in rabbits with conditioned reflex to light (1st group) and sound (2nd group). Relative number of neurones pairs acting in correlation in the areas remote from each other, in intersignal intervals both before and after stimuli did not differ in the 1st and 2nd groups. At the same time delays in neuronal discharges in one area after the other were different. In the 1st group animals there was a predominance of the number of visual area neurones discharging after sensorimotor with a delay up to 125 ms, in comparison with the number of sensorimotor area neurones discharging after the visual one. In the 2nd group rabbits the number of visual area neurones with such a delay of discharges after sensorimotor was less and, on the contrary, a predominance of sensorimotor area neurones was observed discharging after the visual one. The obtained results allow to suggest that neurones of the visual and sensorimotor neocortex areas form a single functional system in cases when conditioned and unconditioned stimuli are addressed to these areas and when only one of the studied areas is the projection zone for the combined stimuli. Organization of the neurones activity in systems in these two cases is different.     

Physiological properties of sympathetic preganglionic neurones in the thoracic intermediolateral nucleus of the cat

Extracellular spikes were recorded from cell bodies of sympathetic preganglionic neurones in spinal segments T1-T3 of the cat. Each neurone was identified by its antidromic response to electrical stimulation of the sympathetic chain and was found in histological sections to lie within the intermediolateral nucleus. Physiological properties studied in detail included basal activity, spike configuration, and latency of antidromic activation. Also studied, in tests with paired stimuli, were the threshold interstimulus interval evoking two responses, as well as changes in amplitude and latency of the second spike which occurred at intervals near this threshold. Approximately 60% of the units studied were spontaneously active, the rest were silent. Spontaneous activity was characterized by a slow (mean = 3.1 +/- 2.6 (SD) spikes/s), irregular pattern of discharge. With approximately one-third of the cases there was a periodic pattern of discharge in phase with oscillations in blood pressure. This correlation of phasic activity suggests that many of the units studied were involved specifically in cardiovascular function. Silent and spontaneously active units could not be differentiated on the basis of latency of antidromic activation or threshold interstimulus interval; mean latency for the two groups was 7.2 +/- 4.9 ms, mean threshold interval was 6.4 +/- 4.7 ms. Thus, with the exception of basal activity, the physiological properties studied failed to indicate more than a single population of neurones. These results therefore suggest that the sympathetic preganglionic neurones in the intermediolateral nucleus subserving varied autonomic functions share overlapping physiological properties, and that functional differentiation of these neurones may be based on differences in synaptic inputs.     

Comparative study of the activity of medullary respiratory neurones during polypnea triggered by hypothalamic electrical stimulation or by hypothalamic heating (author's transl)

We have compared in "encéphale isolé bas" cats the activity of medullary respiratory neurones during polypnea triggered by electrical stimulation (PSt) or by heating (PTh) of the hypothalamus. The medullary respiratory neurones are classified according to:--their anatomical localization (dorsal or ventral respiratory nucleus);--their axon destination (spinal : bulbo-spinal respiratory neurones; non spinal : propriobulbar neurones);--their discharge pattern;--the correlation coefficient between the number of spikes delivered in each burst and the duration of the corresponding respiratory phase (HILAIRE et MONTEAU, 1975). 1. During the two polypneas (PSt and PTh), we observe:--a reduction of activity that preferentially affects some groups of neurones (propriobulbar neurones) (fig. 3);--an inversion of the discharge firing rate, which increases during inspiration in normopnea and decreases in polypnea (fig. 1; fig. 6);--a decrease of the maximal discharge firing rate for the neurones of different groups (Table V). 2. However, two differences exist : during PSt, the maximal discharge firing rate increases for the inspiratory bulbo-spinal neurones of the dorsal nucleus and for the early-burster inspiratory propriobulbar neurones. The recruitment of the bulbo-spinal inspiratory neurones seems to be different; they are activated earlier during PSt than during PTh (Table VI). 3. Some of the observed differences are probably quantitative and we think that polypnea triggered by hypothalamic electrical stimulation is a good model for thermal polypnea.     

Neurophysiology of the vibration sense in locusts and bushcrickets: The responses of ventral-cord neurones

In the locustid Locusta migratoria and the tettigoniids Decticus verrucivorus and Tettigonia cantans, comparative aspects of physiological properties of vibratory/auditory ventral-cord neurones were studied by single cell recordings.These neurones all receive inputs from both vibratory and auditory receptors. Nevertheless, they can be classified into “V neurones” responding preferentially to vibration stimuli, “VS neurones” responding to vibration and airborne sound, and “S neurones” responding preferentially to airborne sound. In every group, there are several types with different physiological properties, normally represented by one neurone on each body side.In Locusta and in the tettigoniid species, the same physiological types of vibratory/auditory neurones were found, although there are differences in the synaptic connectivity of the vibration receptors of the different legs. In Locusta, the middle leg receptors have the strongest influence on the generation of suprathreshold responses of the central neurones, whereas in the tettigoniids the receptors of the ipsilateral fore leg are the most influential.Two of the V neurones receive inputs mainly from campaniform sensilla and other low-frequency vibration receptors, the other V and VS neurones are mainly influenced by the subgenual receptors. Central information processing results in preferential responses to different frequency/intensity ranges in different neurones.Most VS neurone types show the same response characteristics (e.g. time pattern of response, habituation) either to vibration or to airborne-sound stimuli. Simultaneous presentation of both stimuli leads to qualitative changes in the response characteristics. Therefore, the co-processing of auditory and vibratory signals seems to be very important in the acoustic behaviour of grasshoppers.     

Adrenal versus nonadrenal sympathetic preganglionic neurones in the lower thoracic intermediolateral nucleus of the cat: physiological properties

Adrenal and nonadrenal sympathetic preganglionic neurones (SPNs) in the intermediolateral nucleus of spinal segments T8-T10 in the cat were compared according to a number of physiological properties. An SPN was classified as "adrenal" (n = 37) if it could be antidromically activated by electrical stimulation of the adrenal medulla. An SPN that could not be activated from the adrenal medulla yet could be antidromically activated by electrical stimulation of the greater splanchnic nerve was classified as "nonadrenal" (n = 123). Approximately 50% of adrenal SPNs (17 out of 37) were activated antidromically by stimulation of both the greater splanchnic nerve and adrenal medulla, suggesting that these neurones projected to the adrenal medulla via the greater splanchnic nerve, with the other adrenal SPNs taking a different route. The mean conduction velocities of adrenal (6.7 +/- 1.8 (SD) m/s) and nonadrenal (6.7 +/- 1.5 m/s) sympathetic preganglionic axons were similar. Over 80% of adrenal (31 out of 37) and nonadrenal (104 out of 116) SPNs were spontaneously active. The two types of neurone were indistinguishable in terms of the rates and patterns of discharge. Adrenal SPNs discharged with a mean rate of 1.4 +/- 1.1 spikes/s, and nonadrenal SPNs discharged with a mean rate of 1.8 +/- 1.4 spikes/s. With both types of SPN, the pattern of spontaneous activity was either irregular or phasic. With the latter pattern, periodic bursts of discharge were at the same frequency as oscillations in arterial pressure, frequency of ventilation, or phrenic nerve discharge. These data suggest that adrenal and nonadrenal sympathetic preganglionic neurones in the intermediolateral nucleus in caudal thoracic segments share a number of common physiological properties.     

Adrenal versus nonadrenal sympathetic preganglionic neurones in the lower thoracic intermediolateral nucleus of the cat: effects of serotonin, substance P, and thyrotropin-releasing hormone.

Adrenal and nonadrenal sympathetic preganglionic neurones (SPNs) in the intermediolateral nucleus of spinal segments T8-T10 in the cat were compared according to their responses to iontophoretic application of serotonin, substance P, and thyrotropin-releasing hormone (TRH). Responses of both types of SPN to iontophoretic application of serotonin were characterized by an increase in the rate of discharge that was slow in onset (mean +/- SD = 36 +/- 21 s) and prolonged in afterdischarge (115 +/- 70 s) following termination of application. Depression was never observed and responses were similar whether using serotonin at a pH of 3.3 or 4.5, suggesting that the absence of a depressant effect cannot be accounted for by pH, as has been reported with cortical neurones. Iontophoretic application of methysergide resulted in a decrease in the rate of discharge of both types of SPN and blocked the excitatory responses to serotonin. Adrenal and nonadrenal SPNs were excited by iontophoretic application of substance P. Responses of both types of SPN were similar and were characterized by a gradual increase in the rate of discharge that was slow in onset (42 +/- 27 s) and prolonged in afterdischarge (96 +/- 42 s). Finally, adrenal and nonadrenal SPNs were also weakly excited by iontophoretic application of TRH. These responses were slow in onset (48 +/- 27 s) and prolonged in afterdischarge (78 +/- 35 s). These data indicate that serotonin, substance P, and TRH exert excitatory effects on functionally dissimilar sympathetic preganglionic neurones and support the possibility that they may be chemical mediators of synaptic transmission in the intermediolateral nucleus. In addition, these data may be interpreted to support the notion that serotonin, substance P, and TRH are involved in global activation of the sympathetic nervous system.     

Temporal selectivity for complex signals by single neurons in the torus semicircularis of Pleurodema thaul (Amphibia: Leptodactylidae)

Responses of auditory neurons in the torus semicircularis (TS) of Pleurodema thaul, a leptodactylid from Chile, to synthetic stimuli having diverse temporal patterns and to digitized advertisement calls of P. thaul and three sympatric species, were recorded to investigate their temporal response selectivities. The advertisement call of this species consists of a long sequence of sound pulses (a pulse-amplitude-modulated, or PAM, signal) having a dominant frequency of about 2000 Hz. Each of the sound pulses contains intra-pulse sinusoidal-amplitude-modulations (SAMs). Synthetic stimuli consisted of six series in which the following acoustic parameters were systematically modified, one at a time: PAM rate, pulse duration, number of pulses, and intra-pulse SAM rate. The carrier frequency of these stimuli was set at the characteristic frequency (CF) of the isolated units (n = 47). Response patterns of TS units to synthetic call variants reveal different degrees of selectivities for each of the temporal variables, with populations of neurons responding maximally to specific values found in the advertisement call of this species. These selectivities are mainly shaped by neuronal responsiveness to the overall sound energy of the stimulus and by the inability of neurons to discharge to short inter-pulse gaps. Accepted: 30 October 1996     

Neural response to very low-frequency sound in the avian cochlear nucleus

Recordings were made in the chick cochlear nucleus from neurons that are sensitive to very low frequency sound. The tuning, discharge rate response and phase-locking properties of these units are described in detail. The principal conclusions are: 1. Low frequency (LF) units respond to sound frequencies between 10-800 Hz. Best thresholds average 60 dB SPL, and are occasionally as low as 40 dB SPL. While behavioral thresholds in this frequency range are not available for the domestic chick, these values are in good agreement with the pigeon behavioral audiogram (Kreithen and Quine 1979). 2. About 60% of the unit population displays tuning curves resembling low-pass filter functions with corner frequencies between 50-250 Hz. The remaining units have broad band-pass tuning curves. Best frequencies range from 50-300 Hz. 3. Spontaneous discharge rate was analyzed quantitatively for LF units recorded from nucleus angularis. The distribution of spontaneous rates for LF units is similar to that seen from higher CF units (300-5000 Hz) found in the same nucleus. However, the spontaneous firing of LF units is considerably more regular than that of their higher CF counterparts. 4. Low frequency units with low spontaneous rates (SR's less than 40 spikes/s) show large driven rate increases and usually saturate by discharging once or twice per stimulus cycle. Higher SR units often show no driven rate increases. 5. All LF units show strong phase-locking at all excitatory stimulus frequencies. Vector strengths as high as 0.98 have been observed at moderate sound levels. 6. The preferred phase of discharge (relative to the sound stimulus) increases with stimulus frequency in a nearly linear manner. This is consistent with the LF units being stimulated by a traveling wave. The slope of these phase-frequency relationships provides an estimate of traveling wave delay. These delays average 7.2 ms, longer than those seen for higher CF auditory brainstem units. These observations suggest that the peripheral site of low frequency sensitivity is the very distal region of the basilar papilla, an area whose morphology differs significantly from the rest of the chick basilar papilla. 7. LF units are described whose response to sound is inhibitory at frequencies above 50 Hz.     

Reactivity of neurons of the orbito-frontal cortex of the cat during exposure to the scent or sight of food

Reactivity of neurones in orbitofrontal cortex of the cat to the action of light or sound was studied in consecutive stages of alimentary behaviour conditioned by the smell and then the sight of food. Changes were found of the character of neuronal reactions to the light and sound stimuli at the change of smell to the sight of food. A conclusion is drown, that polysensory properties of the neurones of the orbitofrontal cortex provide integral organization of brain sensory function at separate stages of alimentary behaviour.     

次声作用对大鼠血浆SOD、MDA、NO 水平的影响*

目的:通过观察16 Hz/130 dB次声作用大鼠不同时间其血浆超氧化物歧化酶(SOD)、丙二醛(MDA)、一氧化氮(NO)水平的变化,揭示次声作用对大鼠氧化应激损伤的特点。方法:80只SD大鼠随机分为次声作用1、7、14、21和28 d组及对应的假暴露组,每组8只大鼠。次声暴露组每日定时在次声舱内接受16 Hz/130 dB次声作用2h,连续1、7、14、21和28 d,假暴露组除不施加次声作用外,其在次声舱中放置的时间、次数、采样时间点均和次声暴露组相同。次声暴露后即刻测定大鼠血浆SOD、MDA、NO水平,测得的结果与假暴露组进行比较。结果:与假暴露组相比,大鼠血浆SOD活力在次声作用后显著降低(P<0.05),且随次声作用时间延长,SOD活力逐渐降低;大鼠血浆MDA含量在次声作用后显著升高(P<0.05),且随次声作用时间延长,MDA含量逐渐升高;大鼠血浆NO含量在次声作用7、14 d时显著降低(P<0.05),1、21和28 d时无统计学差异(P>0.05)。结论:次声作用可引起大鼠氧化应激损伤,损伤的程度与次声暴露时间有关。     

Audiogram of the chicken (Gallus gallus domesticus) from 2 Hz to 9 kHz

The pure-tone thresholds of four domestic female chickens were determined from 2 Hz to 9 kHz using the method of conditioned suppression/avoidance. At a level of 60 dB sound pressure level (re 20 μN/m²), their hearing range extends from 9.1 Hz to 7.2 kHz, with a best sensitivity of 2.6 dB at 2 kHz. Chickens have better sensitivity than humans for frequencies below 64 Hz; indeed, their sensitivity to infrasound exceeds that of the homing pigeon. However, when threshold testing moved to the lower frequencies, the animals required additional training before their final thresholds were obtained, suggesting that they may perceive frequencies below 64 Hz differently than higher frequencies.     

Convergent properties of 3 types of visual cortex neurons recorded with various action potential amplitudes

Responses of visual cortex neurones recorded with large (N1), mean (N2) and small (N3) amplitudes of action potentials to photic, acoustic and electro-cutaneous stimuli were studied. It was shown that N1 neurones as differing from N3 were predominantly polymodal, often reacted with inhibitory responses and their background activity was characterized by random distribution of interstimuli intervals. Inputs for heteromodal stimuli were found to differ in N1 and N3 neurones. The results suggest existence of functional heterogeneity of neurones, recorded with different action potential amplitudes.     

家鸽峡核神经元的形态

本文采用Golgi-Cox浸染法,研究了家鸽峡核神经元的形态。按其主树突的分布图式,可将鸽峡核神经元分成三类:(1)单极神经元,(2)双极神经元和(3)多极神经元。峡核两部分(Imc和Ipc)的神经元在胞体大小、树突粗细及其伸展趋势上均有明显差别。     

Single unit activity in the guinea-pig cochlear nucleus during sleep and wakefulness.

The effects of waking and sleep on the response properties of auditory units in the ventral cochlear nucleus (CN) were explored by using extracellular recordings in chronic guinea-pigs. Significant increases and decreases in firing rate were detected in two neuronal groups, a) the "sound-responding" and b) the "spontaneous" (units that do not show responses to any acoustic stimuli controlled by the experimenter). The "spontaneous" may be considered as belonging to the auditory system because the corresponding units showed a suppression of their discharge when the receptor was destroyed. The auditory CN units were characterized by their PSTH in response to tones at their characteristic frequency and also by the changes in firing rate and probability of discharge evaluated during periods of waking, slow wave and paradoxical sleep. The CNS performs functions dependent on sensory inputs during wakefulness and sleep phases. By studying the auditory input at the level of the ventral CN with constant sound stimuli, it was shown that, in addition to the firing rate shifts, some units presented changes in the temporal probability of discharge, implying central actions on the corresponding neurons. The mean latency of the responses, however, did not show significant changes throughout the sleep-waking cycle. The auditory efferent pathways are postulated to modulate the auditory input at CN level during different animal states. The probability of firing and the changes in the temporal pattern, as shown by the PSTH, are thus dependent on both the auditory input and the functional brain state related to the sleep-waking cycle.     

The characteristics of the neuronal reactions of the cat somatosensory cortex to a heteromodal complex conditioned signal]

On alert cats the change was studied of the activity of the neurones of the sensorimotor cortical area at instrumental reaction to a simultaneous heteromodal complex stimulus. It was shown that in the projection of distal limb areas a group could be singled out of neurones, which changed their activity in one direction depending on the character of presented signals. In these cells an increase of discharges frequency was observed in response to complex stimulus, consisting of light and sound signals. After the extinction of the motor reaction both to the complex stimulus and to its components neuronal reactions of lesser intensity was recorded, what determined the absence of the motor reaction. This group of neurones had receptive fields localized on distal limb areas, it was activated at fulfillment of the movement of catching the reinforcement and belonged to neurones of the pyramidal tract. The neurones with receptive fields on the whole limb surface or changing their activity at the animal pose change, had variable reactions to positive and differentiation stimuli.     

Dynamics of the activity of rabbit visual cortex neurons during elaboration of elementary conditioned reflexes to time and association

Elaboration of a reflex to time (with omissions of stimuli) and of association; light--light + electrocutaneous stimulation of the paw was studied on neurones of the rabbit visual cortex. It was shown that by similarity of patterns of the discharge to a conditioned stimulus and to reinforcement, 83% of neurones reveal the formation of a reflex to time, and 57%--elaboration of association. Three ways of coding plastic reorganizations of the neuronal discharges are suggested; by the total number of spikes in the response, by the total sum of inhibitory periods, and by the pattern of the response. It has been found that in the reflex to time the early components of the response to the stimulus are reproduced during omissions; in elaboration of the association the late components of the discharge reaction to reinforcement are mainly repeated. Most cells with plastic reorganizations possessed polysensority and revealed discharge sensitization during habituation.     

Conditioned reactions of hippocampal neurons during amphetamine poisoning and its counteraction with haloperidol

Activity of 144 neurones of the dorsal part of the rabbits hippocamp was recorded during elaboration of motor conditioned reflex to time. Chronic amphetamine intoxication lowered the ability of hippocampal neurones to form conditioned reactions in response to pairings of sound stimuli with electrocutaneous reinforcement and fully suppressed mechanisms of reproduction by cells of engrams of previous pairings in series of their omissions Single administration of haloperidol to intact animals somewhat increased the number of neurones reacting to the pairing and their omissions in conditioned reflex to time without significantly influencing the intensity and dynamics of reproduction of endogenous cellular reactions in the series of consecutive omissions of pairing. Haloperidol administration during amphetamine intoxication elicited shifts towards normalization of conditioned activity of neurones, eliminating the suppressing action of amphetamine on mechanisms of reproduction of engrams of combined stimuli. Such "therapeutic" effect of haloperidol in many cases did not depend on the character of its psychotropic action. The properties of amphetamine and haloperidol action on the cells of the hippocamp are discussed as compared to their action on the neurones of other brain structures, previously studied in an analogous experimental situation.     

Electrophysiological responses from the peripheral olfactory system of the American eel,Anguilla rostrata

Summary A method is described for recording with microelectrodes from central neurones in locusts,Schistocerca gregaria americana, that are free to perform a large fraction of their behavioural repertoire. This tethered preparation has been used to examine the individual responses of large neurones in the neck connectives to a range of sensory stimuli.From differences in the responses of the units examined and from their positions in the connective, as determined by dye iontophoresis, 31 separate neurones have been identified. The axons of these cells had relatively constant diameters and cord positions in different animals and appeared in both right and left connectives but with their positions mirror reversed. The majority of these 31 cells carried descending information from the head ganglia and under our experimental conditions, 7 were found to have wind stimulation as their strongest sensory input, 17 had visual stimulation, 4 had sound stimulation and 3 had proprioceptive input.Abbreviations DCMD descending contralateral movement detector (neurone) - DIMD descending ipsilateral movement detector (neurone)     

Infrasound in the flutter jumps of the capercaillie (Tetrao urogallus): apparently a physical by-product

We have tested our assumption that infrasound from flutter jumps of displaying cocks is significant for capercaillie (Tetrao urogallus) orientation. Seven captive females were used for playback experiments during a period when they were extremely disposed to mating and thus expected to respond intensively to signals from males. However, no behavioural response was found, neither to infrasound nor to the audible sound from flutter jumps. We suggest that flutter jumps have only visual functions and that infrasound is nothing but a physical by-product. In large mammals, also, the role of infrasound for communication is as yet uncertain.     

Infrasound in the capercaillie ( Tetrao urogallus )

We examined the sounds made by displaying male capercaillies on a lek in the Black Forest for infrasonic components. Vocalizations did not contain infrasound, whereas flutter jumps produced substantial low-frequency sound energy, with regularly spaced frequency peaks and maximum energy below 20 Hz. This pattern was found in recordings from different distances and for all tested individuals. Nonvocal infrasound may be significant in territorial behavior or orientation of capercaillie.