共查询到20条相似文献,搜索用时 15 毫秒
1.
J. R. McKibben A. H. Bass 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,184(6):563-576
The midshipman fish, Porichthys notatus, generates acoustic signals for intraspecific communication. Nesting males produce long-duration “hums” which attract gravid
females and can be effectively mimicked by pure tones. In this study we examine the encoding of tonal signals by the midshipman
peripheral auditory system. Single-unit recordings were made from afferents innervating the sacculus while presenting sounds
via an underwater loudspeaker. Units were characterized by iso-intensity spike rate and vector strength of synchronization
curves, as well as by peri-stimulus time histograms. Additionally, response-intensity curves and responses to long-duration
(up to 10 s) stimuli were obtained. As has been seen in other teleosts, afferents had highly variable activity profiles. Excitatory
frequencies ranged from 60 to over 300 Hz with most units responding best around 70 or 140 Hz. Thresholds at 90 Hz ranged
from 95 to 145 dB re 1 μPa. Strong synchronization provided a robust temporal code of frequency, comparable to that described
for goldfish. Spike rate showed varying degrees of adaptation but high rates were generally maintained even for 10-s stimuli.
The midshipman peripheral auditory system is well suited to encoding conspecific communication signals, but nonetheless shares
many response patterns with the auditory system of other teleosts.
Accepted: 10 February 1999 相似文献
2.
A G Vasil'ev T I Grigor'eva E A Pavlikova 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1988,38(6):1119-1125
Elaboration of differentiation between sound stimuli was carried out in 15 laboratory rats. After bilateral ablations of auditory inferior colliculi the border frequency of stimulus amplitude modulation was determined for all rats when they still could differentiate between tonal and amplitude-modulated stimuli. Decrease in frequency of modulation by 2 Hz and more from the border frequency caused a complete loss of ability to differentiate. In all rats bilateral inferior colliculi ablations completely disturbed differentiation between tonal and amplitude-modulated signals with modulation frequency below 183-191 Hz (the range of border frequencies). The surgery however did not affect differentiation between tonal and amplitude-modulated signals with the modulation frequencies above 183-191 Hz. The data suggest that the functions of completion of coding of amplitude-modulated stimuli in the auditory system is strictly linked with definite structures. 相似文献
3.
A. S. Khachunts 《Neurophysiology》1982,14(3):191-198
Experiments on waking curarized turtles showed that auditory representation is located in the mediodorsal zone of the tegmentum, in the torus semicircularis, which contains monomodal auditory and bimodal somatoauditory neurons. The somatosensory system is represented more widely and overlaps in the medial zones with the auditory system. Its focus is located in the lateral zones of the dorsal tegmentum (n. intercollicularis), where monomodal somatic neurons were found. Predominance of contralateral somatic projections was discovered. Frequency-threshold curves, obtained by analysis of evoked potentials, were flattened Y-shaped. The range of frequencies received was 40–6000 Hz and the range of optimal frequencies 100–400 Hz. Responses of midbrain auditory neurons could be divided into three principal types: phasic, tonic, and bursting. Neurons with a phasic type of response were characterized by tuning to one optimal frequency, whereas most neurons with responses of tonic type were equally sensitive to two or even three frequencies.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 14, No. 3, pp. 260–269, May–June, 1982. 相似文献
4.
Dagmar Vogel Horst Bleckmann 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(6):671-681
The surface-feeding fish Aplocheilus lineatus uses its cephalic lateral line to detect water surface waves caused by prey insects. The ability of Aplocheilus to discriminate between surface waves with aid of the lateral line system was tested by go/no-go conditioning. Our results
show that Aplocheilus can distinguish between single-frequency surface wave stimuli with equal velocity or equal acceleration amplitudes which
differ only in frequency. Frequency difference limens were about 15%, i.e. fish distinguished a 20-Hz wave stimulus from a
23-Hz stimulus in 100% of the trials. Aplocheilus can also discriminate between pure sine-wave stimuli and sine waves which show abrupt frequency changes. In contrast, fish
were unable to distinguish amplitude-modulated wave stimuli (carrier frequency 20, 40 and 60 Hz, modulation frequency 10 and
20 Hz) from pure sine waves of the same frequency, even if amplitude modulation depth was 80%.
Accepted: 27 December 1996 相似文献
5.
A. G. Vasil'ev 《Neurophysiology》1976,8(1):25-32
Single unit responses in the superior olive of the greater horseshoe bat to ultrasonic stimuli with a filling frequency within the echolocation range were investigated. Some neurons were found to have three completely unconnected response regions with characteristic frequencies of 1/2 and 1/3 of the basic frequency, which was within the 80–86 kHz band. An increase in strength of the stimulus with filling frequency equal to the characteristic frequency of the neuron changed the tonic regime of activity into phasic. Presentation of two stimuli, overlapping in time, replaced the phasic regime by tonic. The frequency of the tonic response corresponded exactly to the beating frequency up to 1200 Hz (synchronization of unit discharges with each beating cycle). The synchronized tonic regime was preserved to definite strengths and filling frequencies of the two stimuli.A. A. Zhdanov State University, Leningrad. Translated from Neirofiziologiya, Vol. 8, No. 1, pp. 30–38, January–February, 1976. 相似文献
6.
J. Mogdans H. Bleckmann 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,185(2):173-180
This report describes the responses of single afferent fibers in the posterior lateral line nerve of the goldfish, Carassius auratus, to pure tone and to amplitude-modulated sinusoidal wave stimuli generated by a dipole source (stationary vibrating sphere).
Responses were characterized in terms of output-input functions relating responses to vibration amplitude, peri-stimulus time
histograms relating responses to stimulus duration, and the degree of phase-locking to both the carrier frequency and the
modulation frequency of the amplitude-modulated stimulus. All posterior lateral line nerve fibers responded to a pure sine
wave with sustained and strongly phase-locked discharges. When stimulated with amplitude-modulated sine waves, fibers responded
with strong phase-locking to the carrier frequency and, in addition, discharge rates were modulated according to the amplitude
modulation frequency. However, phase-locking to the amplitude modulation frequency was weaker than phase-locking to the carrier
frequency. The data indicate that the discharges of primary lateral line afferents encode both the carrier frequency and the
modulation frequency of an amplitude-modulated wave stimulus.
Accepted: 2 June 1999 相似文献
7.
K.-H. Esser B. Lud 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):513-522
In the lesser spear-nosed bat, Phyllostomus discolor, maternal directive calls are characterized by an individual type of sinusoidal frequency modulation (= SFM) pattern. Beside
modulation frequency, modulation depth, carrier frequency, and number of modulation cycles per call contribute to the mother's
vocal signature. Since juvenile P. discolor learn to adapt their isolation calls to the corresponding call characteristics of the own mother or even to playback of a
computer-stored directive call, if hand-reared in the absence of conspecifics, the bats' auditory system ought to be able
to resolve interindividual differences in communication call structure. However, quantitative psychoacoustic data on the discrimination
of SFM signals in this species are not available. Thus, in the present study, lesser spear-nosed bats were trained in a two-alternative
forced-choice procedure to discriminate between two alternatingly presented SFM sound signals differing in modulation frequency.
Other characteristics of acoustic stimuli were identical and designed to mimick the fundamental of species-specific calls.
By gradually reducing the difference in modulation frequency between both stimuli within the behavioural relevant range until
the animals' performance dropped below the 75%-correct level, a considerable auditory spectro-temporal resolution has been
revealed. Particularly in comparison to the overall interindividual variation of this call parameter (minimal modulation frequency = 49 Hz,
maximum = 100 Hz), the determined average difference limen for modulation frequency of 2.42 ± 0.29 Hz seems substantial and
sufficient for labelling individuals.
Accepted: 30 November 1996 相似文献
8.
Jakob Christensen-Dalsgaard Morten Buhl Jørgensen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,164(4):495-499
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 相似文献
9.
Activity of medullar and midbrain auditory neurons at action of amplitude-modulated tone burst was recorded in immobilized common frogs Rana temporaria. Depth of modulation amounted to 10% or 80%, frequency of modulation varied from 5 to 150 Hz, and carrier intensity was in the range of 20–30 dB. Phasic neurons in medulla clearly reproduced the modulation frequency, but only at the 80% modulation depth. However, during presentation of signal with the 10% modulation depth, these neurons practically did not respond. Tonic neurons were able to reproduce the modulation frequency up to 10–150 Hz, but at the 10% modulation depth, the degree of reproduction of envelope was rather low, although for several first modulation periods it rose statistically significantly. In midbrain, the highest frequency of the reproduced modulation sharply fell. At greater modulation frequencies, the response of these neurons qualitatively reminds that of medullar neurons. At the low modulation frequencies, there is identified a group of midbrain neurons with a prominent increase of the signal modulation. This occurs in the frequency diapason up to 60 Hz; at an increase of the modulation frequency the time of achievement of maximal synchronization decreases. The optimal modulation frequency in many neurons of semicircular torus corresponds to parameters of the male nuptial call. 相似文献
10.
A comparative study of hearing ability in fishes: the auditory brainstem response approach 总被引:7,自引:0,他引:7
T. N. Kenyon F. Ladich H. Y. Yan 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(3):307-318
Auditory brainstem response (ABR) techniques, an electrophysiological far-field recording method widely used in clinical evaluation
of human hearing, were adapted for fishes to overcome the major limitations of traditional behavioral and electrophysiological
methods (e.g., invasive surgery, lengthy training of fishes, etc.) used for fish hearing research. Responses to clicks and
tone bursts of different frequencies and amplitudes were recorded with cutaneous electrodes. To evaluate the effectiveness
of this method, the auditory sensitivity of a hearing specialist (goldfish, Carassius auratus) and a hearing generalist (oscar, Astronotus ocellatus) was investigated and compared to audiograms obtained through psychophysical methods. The ABRs could be obtained between
100 Hz and 2000 Hz (oscar), and up to 5000 Hz (goldfish). The ABR audiograms are similar to those obtained by behavioral methods
in both species. The ABR audiogram of curarized (i.e., Flaxedil-treated) goldfish did not differ significantly from two previously
published behavioral curves but was lower than that obtained from uncurarized fish. In the oscar, ABR audiometry resulted
in lower thresholds and a larger bandwidth than observed in behavioral tests. Comparison between methods revealed the advantages
of this technique: rapid evaluation of hearing in untrained fishes, and no limitations on repeated testing of animals.
Accepted: 8 August 1997 相似文献
11.
Temporal selectivity for complex signals by single neurons in the torus semicircularis of Pleurodema thaul (Amphibia: Leptodactylidae) 总被引:2,自引:0,他引:2
Mario Penna Wen-Yu Lin Albert S. Feng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(4):313-328
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 相似文献
12.
T. Knöpfel B. J. M. Hess W. Precht 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1984,154(2):233-240
Summary Firing behaviour of frog (Rana temporaria) single trochlear motoneurons and multi-unit activity of trochlear nerve were studied during sinusoidal linear accelerations or ramp-hold stimuli (side-up, side-down) in the dark. Frequencies of sinusoidal stimulation ranged from 0.05 Hz to 2 Hz and peak accelerations were between 0.001g and 0.1g.Phase lead of trochlear nerve mass activity relative to imposed acceleration decreased with increasing frequency from 43±10° at 0.1 Hz to 13±6° at 1 Hz for transverse acceleration, and from 37±9° at 0.1 Hz to 1.5±5° at 1 Hz for longitudinal acceleration.The majority of trochlear motoneurons, characterized by short antidromic latencies (<3 ms), had response phases ranging from 52°±6° at 0.05 Hz to 18°±11° at 2 Hz. Their phase behaviour was thus similar to that observed in the nerve multi-unit activity. Response sensitivities typically increased with increasing frequency and showed a clear dependency on stimulus amplitude. In addition, some motoneurons were recorded at antidromic latencies between 3 ms and 6 ms. These units showed less phase lead at frequencies below 0.2 Hz and a rather constant sensitivity in the frequency range tested.The present results together with previous work on primary otolith afferents indicate that information in phasic, phasic-tonic and tonic afferents may be transmitted rather faithfully to motoneurons. This implies that, unlike the case in higher vertebrates, very little central processing occurs in the amphibian maculo-ocular reflex. 相似文献
13.
14.
T I Grigor'eva 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1983,33(3):480-485
Elaboration of differentiation of tonal and amplitude-modulated stimuli with a frequency modulation of 5 Hz conducted on laboratory rats in five months after section of brachii colliculi proved to be impossible. The rate of correct reactions did not differ from the probability of random choice during 500 presentations of conditioned stimuli but significantly differed from the values obtained during differentiation of these signals in rats after control operation. Electrophysiological control showed that while in the control group and in intact animals at the presentation of amplitude-modulated stimuli with modulation frequency of 1-20 Hz summary potentials were recorded in the auditory cortex synchronized with their modulation frequency,--in rats after section of brachii colliculi only on- and off-responses were observed. It may be suggested that sensory providing of conditioned activity during the action of amplitude-modulated stimuli with low modulation frequency may be achieved only with the participation of specific pathways. 相似文献
15.
T I Grigor'eva I I Figurina A G Vasil'ev 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1987,37(2):265-271
In 13 laboratory rats with bilateral auditory cortex ablation, the border frequency of amplitude-modulation still allowing differentiation between tonal and amplitude-modulated stimuli, did not change after bilateral section of the brachii of the posterior colliculi. Bilateral auditory cortex ablation and section of the brachii drastically disturbed this differentiation when the modulation frequencies were higher than 27-31 Hz. The data suggest that the completion of coding of amplitude-modulated stimuli does not take place at the level of the medial geniculate body, and that border frequencies defined after auditory cortex ablation are linked with the frontier posterior colliculi--thalamo-cortical system. 相似文献
16.
Morten Buhl Jørgensen Jakob Christensen-Dalsgaard 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):493-502
We studied the directionality of spike rate responses of auditory nerve fibers of the grassfrog, Rana temporaria, to pure tone stimuli. All auditory fibers showed spike rate directionality. The strongest directionality was seen at low
frequencies (200 – 400 Hz), where the spike rate could change by up to nearly 200␣spikes s−1. with sound direction. At higher frequencies the directional spike rate changes were mostly below 100 spikes s−1. In equivalent dB SPL terms (calculated using the fibers' rate-intensity curves) the maximum directionalities were up to
15 dB at low frequencies and below 10 dB at higher frequencies. Two types of directional patterns were observed. At frequencies
below 500 Hz relatively strong responses were evoked by stimuli from the ipsilateral (+90o) and contralateral (−90o) directions while the weakest responses were evoked by stimuli from frontal (0o or +30o) or posterior (−135o) directions. At frequencies above 800 Hz the strongest responses were evoked by stimuli from the ipsilateral direction while
gradually weaker responses were seen as the sound direction shifted towards the contralateral side. At frequencies between
500 and 800 Hz both directional patterns were seen. The directionality was highly intensity dependent. No special adaptations
for localization of conspecific calls were found.
Accepted: 23 November 1996 相似文献
17.
T. C. Tricas J. G. New 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,182(1):89-101
Elasmobranch fishes localize weak electric sources at field intensities of <5 ηV cm−1, but the response dynamics of electrosensory primary afferent neurons to near threshold stimuli in situ are not well characterized.
Electrosensory primary afferents in the round stingray, Urolophus halleri, have a relatively high discharge rate, a regular discharge pattern and entrain to 1-Hz sinusoidal peak electric field gradients
of ≤20 ηV cm−1. Peak neural discharge for units increases as a non-linear function of stimulus intensity, and unit sensitivity (gain) decreases
as stimulus intensity increases. Average peak rate-intensity encoding is commonly lost when peak spike rate approximately
doubles that of resting, and for many units occurs at intensities <1 μV cm−1. Best neural sensitivity for nearly all units is at 1–2 Hz with a low-frequency slope of 8 dB/decade and a high-frequency
slope of −23 dB/decade. The response characteristics of stingray electrosensory primary afferents indicate sensory adaptations
for detection of extremely weak phasic fields near 1–2 Hz. We argue that these properties reflect evolutionary adaptations
in elasmobranch fishes to enhance detection of prey, communication and social interactions, and possibly electric-mediated
geomagnetic orientation.
Accepted: 20 June 1997 相似文献
18.
Functional organization of the electroreceptive midbrain in an elasmobranch (Platyrhinoidis triseriata) 总被引:1,自引:1,他引:0
Jeff Schweitzer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1986,158(1):43-58
The response properties of 322 single units in the electroreceptive midbrain (lateral mesencephalic nucleus, LMN) of the thornback ray, Platyrhinoidis triseriata, were studied using uniform and local electric fields. Tactile, visual, or auditory stimuli were also presented to test for multimodality. Most LMN electrosensory units (81%) are silent in the absence of stimulation. Those with spontaneous activity fired irregularly at 0.5 to 5 impulses/s, the lower values being more common. Two units had firing rates greater than 10/s. Midbrain electrosensory units are largely phasic, responding with one or a few spikes per stimulus onset or offset or both, but the adaptation characteristics of some neurons are complex. The same neuron can exhibit phasic or phasic-tonic responses, depending upon orientation of the electric field. Tonic units without any initial phasic over-shoot were not recorded. Even the phasic-tonic units adapt to a step stimulus within several seconds. Unit thresholds are generally lower than 0.3 microV/cm, the weakest stimulus delivered, although thresholds as high as 5 microV/cm were recorded, Neuronal responses reach a maximum, with few exceptions, at 100 microV/cm and decrease rapidly at higher intensities. LMN neurons are highly sensitive to stimulus repetition rates: most responded to frequencies of 5 pulses/s or less; none responded to rates greater than 10/s. Three distinct response patterns are recognized. Best frequencies in response to sinusoidal stimuli range from 0.2 Hz (the lowest frequency delivered) to 4 Hz. Responses decrease rapidly at 8 Hz or greater, and no units responded to frequencies greater than 32 Hz. Most LMN neurons have small, well defined excitatory electroreceptive fields (RFs) exhibiting no surround inhibition, at least as detectable by methods employed here. Seventy-eight percent of units recorded had RFs restricted to the ventral surface: of these, 98% were contralateral. The remaining 22% of units had disjunct dorsal and ventral receptive fields. Electrosensory RFs on the ventral surface are somatotopically organized. Anterior, middle, and posterior body surfaces are mapped at the rostral, middle, and caudal levels, respectively, of the contralateral LMN. The lateral, middle, and medial body are mapped at medial, middle, and lateral levels of the nucleus. Moreover, the RFs of all units isolated in a given dorsoventral electrode track are nearly superimposable. About 40% of LMN, measured from the dorsal surface, is devoted to input from ventral electroreceptors located in a small region rostral and lateral to the mouth.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
19.
G. I. Rozhkova V. Y. Vedenina G. Kämper 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,184(2):161-167
The bilateral pairs of cercal interneurons 10-2a and 10-3a in the cricket terminal ganglion are supposed to constitute a
functional system for measuring the direction of air-borne signals, based on their phase-locked responses and selective directional
sensitivity. The purpose of this study was to obtain information on the frequency and intensity characteristics and thus the
potential working range of this system. By recording intracellularly from the axons of the interneurons we measured responses
for stimuli of varying frequency, intensity, and direction. Typically, the stimulus frequency range examined extended from
5 to 600 Hz, at intensities of 0.03–30 mm s−1 (peak-to-peak air-particle velocity). The results show that interneurons 10-2a and 10-3a preserved their level of activity,
response type, and direction tuning in the whole frequency range tested. Stimulus-response cross-correlograms revealed that
spike trains were synchronized with stimulus waves at even higher frequencies, at least up to 1000 Hz. At a given air-particle
velocity in the range of about 2–2.5 logarithmic units, the spike number responses of the interneurons were nearly constant
over a wide frequency range. Directional diagrams appeared to be independent of stimulus frequency, both in orientation and
in amplitude.
Accepted: 14 October 1998 相似文献
20.
Birgit Bigalke-Kunz Rudolf Rübsamen Gerd Joachim Dörrscheidt 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1987,161(2):255-265
1. The diencephalic auditory nucleus of the European starling, the nucleus ovoidalis, shows rostrocaudal and dorsoventral diameters of 500-800 microns and a mediolateral diameter of 800-1000 microns. This small and sharply delimited nucleus is composed of densely packed neurons. 2. Its tonotopic organization consists of evenly spaced isofrequency contours, with best frequencies decreasing ventrally. The frequency range was found to be 150 Hz to 7030 Hz. 3. Apart from tonotopic organization, other characteristics of single units demonstrate the uniformity of the neuronal population. Units have high spontaneous activities (mean 61 pps; Fig. 4a), and show mainly stimulus correlated tonic discharge patterns. In most cases, excitatory frequency bands are enclosed by inhibitory frequency bands. 4. Single units were tested, applying various stimulus classes differing in time structure (BPN, sine, FM up, FM down, SFM, SAM) but sharing a common frequency band. All neurons tested responded to all classes. Evaluation of stimulus class preference, however, revealed that BPN and SFM caused the strongest responses, whereas FM and SAM were less effective. 5. Comparison of the single unit responses in the ovoid nucleus with those known for avian auditory forebrain and midbrain centres strongly suggests a relay function for the diencephalic nucleus. 相似文献