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1.
GABAergic inhibition shapes frequency tuning and modifies response properties in the auditory midbrain of the leopard frog 总被引:3,自引:0,他引:3
J. C. Hall 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,185(5):479-491
The functional role of GABAergic inhibition in shaping the frequency tuning of 96 neurons in the torus semicircularis of
the leopard frog, Rana pipiens, was studied using microiontophoresis of the GABAA receptor antagonist, bicuculline methiodide. Bicuculline application abolished, or reduced in size, the inhibitory tuning
curves of 72 neurons. In each case, there was a concommitant broadening of the excitatory tuning curve such that frequency-intensity
combinations that were inhibitory under control conditions, became excitatory during disinhibition with bicuculline methiodide.
These effects were observed irrespective of the excitatory tuning curve configuration prior to bicuculline methiodide application.
Results indicate an important role for GABA-mediated inhibition in shaping the frequency selectivity of neurons in the torus
semicircularis of the leopard frog. Bicuculline application also affected several other response properties of neurons in
the leopard frog torus. Disinhibition with bicuculline methiodide increased both the spontaneous firing rate (18 cells) and
stimulus-evoked discharge rate (81 cells) of torus neurons, decreased the minimum excitatory threshold for 18 cells, and altered
the temporal discharge pattern of 47 neurons. Additional roles for GABAergic inhibition in monaural signal analysis are discussed.
Accepted: 25 August 1999 相似文献
2.
Curtis J. Condon Su-Hua Chang Albert S. Feng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,168(6):709-725
Summary Response characteristics of 130 single neurons in the superior olivary nucleus of the northern leopard frog (Rana pipiens pipiens) were examined to determine their selectivity to various behaviorally relevant temporal parameters [rise-fall time, duration, and amplitude modulation (AM) rate of acoustic signals. Response functions were constructed with respect to each of these variables. Neurons with different temporal firing patterns such as tonic, phasic or phasic-burst firing patterns, participated in time domain analysis in specific manners. Phasic neurons manifested preferences for signals with short rise-fall times, thus possessing low-pass response functions with respect to this stimulus parameter; conversely, tonic and phasic-burst units were non-selective and possessed all-pass response functions. A distinction between temporal firing patterns was also observed for duration coding. Whereas phasic units showed no change in the mean spike count with a change in stimulus duration (i.e., all-pass duration response functions), tonic and phasic-burst units gave higher mean spike counts with an increase in stimulus duration (i.e., primary-like high-pass response functions). Phasic units manifested greater response selectivity for AM rate than did tonic or phasic-burst units, and many phasic units were tuned to a narrow range of modulation rates (i.e., band-pass). The results suggest that SON neurons play an important role in the processing of complex acoustic patterns; they perform extensive computations on AM rate as well as other temporal parameters of complex sounds. Moreover, the response selectivities for rise-fall time, duration, and AM rate could often be shown to contribute to the differential responses to complex synthetic and natural sounds.Abbreviations
SON
superior olivary nucleus
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DMN
dorsal medullary nucleus
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TS
torus semicircularis
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FTC
frequency threshold curve
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BF
best excitatory frequency
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PAM
pulsatile amplitude modulation
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SAM
sinusoidal amplitude modulation
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SQAM
square-wave amplitude modulation
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MTF
modulation transfer function
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PSTH
peri-stimulus time histogram 相似文献
3.
Effects of GABA-mediated inhibition on direction-dependent frequency tuning in the frog inferior colliculus 总被引:1,自引:0,他引:1
H. Zhang J. Xu A. S. Feng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,184(1):85-98
Earlier studies from our laboratory have shown that the frequency selectivity of neurons in the frog inferior colliculus
is direction dependent. The goal of this study was to test the hypotheses that gamma-aminobutyric acid or GABA (but not glycine)-mediated
synaptic inhibition was responsible for the direction-dependence in frequency tuning, and that GABA acted through creation
of binaural inhibition. We performed single unit recordings and investigated the unit's free-field frequency tuning, and/or
the unit's response to the interaural level differences (under dichotic stimulation), before and during local applications
of antagonists specific to gamma-aminobutyric acid a and glycine receptors. Our results showed that application of bicuculline produced a broadening of free-field frequency tuning,
and differential changes in free-field frequency tuning depending on sound direction, i.e., more pronounced at azimuths at
which the unit exhibited narrower frequency tuning under the pre-drug condition, thereby typically abolishing direction dependence
in tuning. Application of strychnine produced no change in frequency tuning. The results from dichotic stimulation further
revealed that bicuculline typically elevated and/or flattened the unit's interaural-level-difference response function, indicating
a reduction in the strength of binaural inhibition. Our study provides evidence that gamma-aminobutyric acid-mediated binaural
inhibition is important for direction dependence in frequency tuning.
Accepted: 24 July 1998 相似文献
4.
Caroly A. Shumway Leonard Maler 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,164(3):391-407
1. The amplitude-coding pyramidal neurons of the first-order nucleus in weakly electric gymnotiform fish (Eigenmannia), the electrosensory lateral line lobe (ELL), exhibit 2 major physiological transformations of primary afferent input. Pyramidal cells rapidly adapt to a step change in amplitude, and they have a center/surround receptive-field organization. This study examined the physiological role of GABAergic inhibition on pyramidal cells. GABAergic synapses onto the somata of pyramidal cells primarily originate from granule-cell interneurons along with descending input. 2. Pyramidal cells fall into two physiologically distinct categories: E units, which are excited by a rise in stimulus amplitude, and I units, which are inhibited by a rise in stimulus amplitude. Microiontophoretic application of bicuculline methiodide onto both types of pyramidal cells increased the time constant of adaptation, defined as the time required for the neuron's response to decay to 37% of its maximum value, by 70-90%. The peak firing rate of E units to a step increase in stimulus amplitude increased by 49%, while the firing rate of I units did not change significantly. 3. Bicuculline application demonstrated that GABAergic inhibition may contribute to the strict segregation of E and I response properties. In the presence of bicuculline, many E units (normally excited only by stimulus amplitude increases) became excited by both increases and decreases; many I units (normally excited only by amplitude decreases) also became excited to increases. 4. The size of the excitatory receptive-field of E units was not affected by bicuculline, although response magnitude increased. The inhibitory surround increased in spatial extent by 175% with bicuculline administration. Neither the size of the I unit receptive-field center nor the response magnitude changed in the presence of bicuculline. The antagonistic surround of I units, however, increased by 49%. 5. The anatomy of the ELL is well understood (see Carr and Maler 1986). The physiological results obtained in this study, along with the results of Bastian (1986a, b), further our understanding of the functional role of the ELL circuitry. Our results suggest that spatial and temporal response properties of pyramidal cells are regulated by different but interacting inhibitory interneurons, some of which use GABA as a neurotransmitter. The activity of these interneurons is in turn controlled by descending feedback systems. 相似文献
5.
《Current biology : CB》2023,33(11):2260-2269.e4
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H. Zhang A. S. Feng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(6):725-735
Single-unit recordings were made from the frog inferior colliculus to determine whether or not the direction-dependent sharpening
of a unit's free-field excitatory frequency-threshold curve (FTCe) was accompanied by a broadening of its inhibitory frequency-threshold curve (FTCi). To determine the FTCi, a two-tone-suppression paradigm was employed. The unit's FTCis and FTCes were collected at three azimuths: contralateral to the recording site, ipsilateral to the recording site, and frontal midline.
The result showed that: (1) most inferior colliculus neurons (95%) displayed two-tone suppression, (2) the majority (54%)
of neurons displayed stronger two-tone-suppression leading to broader FTCis when the sound was presented from the ipsilateral side than from the contralateral side, (3) for some neurons, the borders
of the FTCes and FTCis were closely aligned, and this juxtaposition persisted at all sound azimuths (namely, when a change in sound direction produced
a narrowing of a unit's FTCe, its FTCi was broadened concomitantly). For the remaining neurons, however, direction-dependent sharpening of the FTCe was not accompanied by an increase in two-tone-suppression. The neural mechanisms that underlie the direction-dependent changes
in the FTCes and FTCis are discussed.
Accepted: 19 November 1997 相似文献
10.
Tonic GABAergic inhibition of taste-responsive neurons in the nucleus of the solitary tract 总被引:4,自引:1,他引:3
The effects of gamma-aminobutyric acid (GABA) and the GABAA receptor
antagonist bicuculline methiodide (BICM) on the activity of taste-
responsive neurons in the nucleus of the solitary tract (NST) were examined
electrophysiologically in urethane-anesthetized hamsters. Single neurons in
the NST were recorded extracellularly and drugs (21 nl) were microinjected
into the vicinity of the cell via a multibarrel pipette. The response of
each cell was recorded to lingual stimulation with 0.032 M NaCl, 0.032 M
sucrose, 0.0032 M citric acid and 0.032 M quinine hydrochloride (QHCl).
Forty-six neurons were tested for the effects of GABA; the activity of 29
cells (63%) was inhibited by 5 mM GABA. Whether activity was elicited in
these cells by repetitive anodal current stimulation (25 microA, 0.5 s, 0.1
Hz) of the tongue (n = 13 cells) or the cells were spontaneously active (n
= 13 cells), GABA produced a dose-dependent (1, 2 and 5 mM) decrement in
activity. Forty- seven NST neurons were tested for the effects of BICM on
their responses to chemical stimulation of the tongue; the responses of 28
cells (60%) were enhanced by 10 mM BICM. The gustatory responses of 26 of
these cells were tested with three concentrations (0.2, 2 and 10 mM) of
BICM, which produced a dose-dependent increase in both spontaneous activity
and taste-evoked responses. Nine of these neurons were sucrose- best, seven
were NaCl-best, eight were acid-best and two responded best to QHCl. The
responses to all four tastants were enhanced, with no difference among
neuron types. For 18 cells that were tested with two or more gustatory
stimuli, BICM increased their breadth of responsiveness to their two most
effective stimuli. These data show that approximately 60% of the
taste-responsive neurons in the rostral NST are inhibited by GABA and/or
subject to a tonic inhibitory influence, which is mediated by GABAA
receptors. The modulation of these cells by GABA provides a mechanism by
which the breadth of tuning of the cell can be sharpened. Modulation of
gustatory activity following a number of physiological changes could be
mediated by such a GABAergic circuit.
相似文献
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Walter Wilczynski Carl Resler Robert R. Capranica 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1987,161(5):659-669
Summary The inner ear of the leopard frog,Rana pipiens, receives sound via two separate pathways: the tympanic-columellar pathway and an extratympanic route. The relative efficiency of the two pathways was investigated. Laser interferometry measurements of tympanic vibration induced by free-field acoustic stimulation reveal a broadly tuned response with maximal vibration at 800 and 1500 Hz. Vibrational amplitude falls off rapidly above and below these frequencies so that above 2 kHz and below 300 Hz tympanic vibration is severely reduced. Electrophysiological measurements of the thresholds of single eighth cranial nerve fibers from both the amphibian and basilar papillae in response to pure tones were made in such a way that the relative efficiency of tympanic and extratympanic transmission could be assessed for each fiber. Thresholds for the two routes are very similar up to 1.0 kHz, above which tympanic transmission eventually becomes more efficient by 15–20 dB. By varying the relative phase of the two modes of stimulation, a reduction of the eighth nerve response can be achieved. When considered together, the measurements of tympanic vibration and the measurements of tympanic and extratympanic transmission thresholds suggest that under normal conditions in this species (1) below 300 Hz extratympanic sound transmission is the main source of inner ear stimulation; (2) for most of the basilar papilla frequency range (i.e., above 1.2 kHz) tympanic transmission is more important; and (3) both routes contribute to the stimulation of amphibian papilla fibers tuned between those points. Thus acoustic excitation of the an uran's inner ear depends on a complex interac tion between tympanic and extratympanic sound transmission.Abbreviations
dB SPL
decibels sound pressure level re: 20 N/ m2
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AP
amphibian papilla
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BP
basilar papilla
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BEF
best excitatory frequency 相似文献
13.
Expression of histocompatibility loci in the leopard frog 总被引:1,自引:0,他引:1
14.
Global and single unit responses of the superior olivary complex were investigated during ultrasonic stimulation at different frequencies in two species of bats from the Vespertilionidae, which emit frequency-modulated signals and the Rhinolophidae, which utilize almost monochromatic (80 ± 1 kHz) echolocation cries. Maximal sensitivity to ultrasound in the Vespertilionidae was found at frequencies of 10–40 kHz, and in the Rhinolophidae also within the range 10–40 kHz but with a second increase in sensitivity in the region 82–86 kHz. Sharply tuned neurons were more numerous in the Rhinolophidae than in the Vespertilionidae. Neurons whose response in the echolocation frequency band changed in character depending on the fill frequency of the stimulus were found in Rhinolophidae: a phasic discharge occurs over a wide range of frequencies and a tonic discharge at the characteristic frequency; the latter was also observed over a limited range of intensities.A. A. Zhdanov Leningrad State University. Translated from Neirofiziologiya, Vol. 5, No. 1, pp. 33–39, January–February, 1973. 相似文献
15.
Frogs rely on acoustic signaling to detect, discriminate, and localize mates. In the temperate zone, reproduction occurs in the spring, when frogs emerge from hibernation and engage in acoustically guided behaviors. In response to the species mating call, males typically show evoked vocal responses or other territorial behaviors, and females show phonotactic responses. Because of their strong seasonal behavior, it is possible that the frog auditory system also displays seasonal variation, as evidenced in their vocal control system. This hypothesis was tested in male Northern leopard frogs by evaluating the response characteristics of single neurons in the torus semicircularis (TS; a homolog of the inferior colliculus) to a synthetic mating call at different times of the year. We found that TS neurons displayed a seasonal change in frequency tuning and temporal properties. Frequency tuning shifted from a predominance of TS units sensitive to intermediate frequencies (700-1200 Hz) in the winter, to low frequencies (100-600 Hz) in the summer. In winter and early spring, most TS neurons showed poor, or weak, time locking to the envelope of the amplitude-modulated synthetic call, whereas in late spring and early summer the majority of TS neurons showed robust time-locked responses. These seasonal differences indicate that neural coding by auditory midbrain neurons in the Northern leopard frog is subject to seasonal fluctuation. 相似文献
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Robert G. McKinnell Georges K. De Bruyne Marc M. Mareel David Tarin Kenyon S. Tweedell 《Differentiation; research in biological diversity》1984,26(1-3):231-234
Abstract. The cytoplasmic microtubule complex (CMTC) was examined in monolayer cultures of normal tadpole mesonephros, primary renal adenocarcinoma, and an established cell line derived from a pronephric renal adenocarcinoma (PNKT-4B) of the leopard frog, Rana pipiens. Immunocytochemistry revealed typical arrays of microtubules extending from the cytocentrum to the cell periphery in all three cell types when cultured at 28° C; similar results were obtained at 20° C. However, the CMTC was disorganized in both tumor types, in contrast to the retention of a typical CMTC in normal tissue cultured at 7° C. The response of PNKT-4B cells differed from that of normal tadpole mesonephros when treated with the microtubule inhibitor drug nocodazole. At 28° C, PNKT-4B and tadpole mesonephros cells lost their CMTC with nocodazole treatment, and both were able to reconstitute CMTC when nocodazole was removed. Similarly, both lost CMTC organization with nocodazole and culture at 7° C. However, while normal cells could effect a recovery at 7° C after the removal of nocodazole, PNKT4B cells were unable to restructure CMTC under the same conditions. Metastasis in the frog renal adenocarcinoma is temperature-dependent, with an elevated prevalence of metastasis in tumor-bearing frogs maintained at 28° C. Few metastatic colonies are detected in tumor-bearing frogs maintained at a low temperature (7° C). Other studies have indicated that microtubules, which are essential for cell motility, play an important role in the invasion by tumor cells of normal tissue fragments in vitro. The effects of temperature on metastasis of the Lucke renal adenocarcinoma are consistent with temperature-mediated changes in tumor-cell CMTC. 相似文献
19.
J. Wang T. A. Ludwig P. M. Narins 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,178(2):159-172
We investigated directionalities of eardrum vibration and auditory nerve response in anesthetized northern leopard frogs (Rana pipiens pipiens). Simultaneous measures of eardrum velocities and firing rates from 282 auditory nerve fibers were obtained in response to free-field sounds from eight directions in the horizontal plane. Sound pressure at the external surface of the ipsilateral eardrum was kept constant for each presentation direction (± 0.5 dB). Significant effects of sound direction on eardrum velocity were shown in 90% of the cases. Maximum or minimum eardrum velocity was observed more often when sounds were presented from the lateral and posterior fields, or from the anterior and contralateral fields, respectively. Firing rates of 38% of the fibers were significantly affected by sound direction and maximum or minimum firing rate was observed more frequently when sounds were delivered from the lateral fields, or from the anterior and contralateral fields, respectively. Directionality patterns of eardrum velocity and nerve firing also vary with sound frequency. Statistically significant correlation between eardrum velocity and nerve fiber firing rate was demonstrated in only 45% of the fibers, suggesting that sound transmission to the inner ear through extratympanic pathways plays a non-trivial role in the genesis of directionality of auditory nerve responses.Abbreviations CF
characteristic frequency
- SVL
snout-vent length
- TM
tympanic membrane 相似文献