RESUMEN
Phase response curves (PRCs) are widely used in circadian clocks, neuroscience, and heart physiology. They quantify the response of an oscillator to pulse-like perturbations. Phase response curves provide valuable information on the properties of oscillators and their synchronization. This chapter discusses biological self-sustained oscillators (circadian clock, physiological rhythms, etc.) in the context of nonlinear dynamics theory. Coupled oscillators can synchronize with different frequency ratios, can generate toroidal dynamics (superposition of independent frequencies), and may lead to deterministic chaos. These nonlinear phenomena can be analyzed with the aid of a phase transition curve, which is intimately related to the phase response curve. For illustration purposes, this chapter discusses a model of circadian oscillations based on a delayed negative feedback. In a second part, the chapter provides a step-by-step recipe to measure phase response curves. It discusses specifications of this recipe for circadian rhythms, heart rhythms, neuronal spikes, central pattern generators, and insect communication. Finally, it stresses the predictive power of measured phase response curves. PRCs can be used to quantify the coupling strength of oscillations, to classify oscillator types, and to predict the complex dynamics of periodically driven oscillations.
Asunto(s)
Relojes Biológicos/fisiología , Animales , Ritmo Circadiano/fisiología , Corazón/fisiología , Humanos , Neuronas/fisiología , Dinámicas no LinealesRESUMEN
Acoustic signals consist of pressure changes over time and can thus be analyzed in the frequency- or in the time-domain. With behavioural experiments we investigated which frequency components (FC) are necessary for the recognition of the periodic envelope of the conspecific song by females of the grasshopper Chorthippus biguttulus. Further, we determined up to which frequency component phase information is required which would indicate processing in the time domain. Responses of females revealed that signals composed of FC between 10 and 50 Hz are sufficient for recognition of the song envelope. A systematic reduction in the number of FC showed that no single frequency component was required; signals without the fundamental frequency were still highly attractive and only three FC may be sufficient for song recognition. Phase changes for frequencies up to 40 Hz strongly changed the attractiveness of song signals but only little at 50 Hz. Females were also tested with rectangular signals in which pause duration was varied. Evidently, and despite the high attractiveness of song signals with a "missing fundamental", females evaluated the attractiveness of signals in the time-domain, since the selectivity for pause duration predicted the responses to signals composed from FC well.
Asunto(s)
Comunicación Animal , Percepción Auditiva/fisiología , Saltamontes/fisiología , Estimulación Acústica , Animales , Señales (Psicología) , Femenino , Larva , Masculino , Conducta Sexual Animal/fisiología , Detección de Señal Psicológica , Factores de TiempoRESUMEN
Nervous systems may encode information about sensory stimuli using the temporal relations in spiking patterns between neurons. By conducting simultaneous intracellular recordings on pairs of auditory neurons we measured the strength of correlations between elements of the first three processing levels in the metathoracic auditory network of the locust. We quantified the degree of spike synchronization and rate covariations that occur among auditory neurons during acoustic stimulation. In addition to the acoustic stimulation, current pulses were injected into both neurons to study the connectivity within this network. Our findings support the view that the metathoracic auditory system is a hierarchically organized feedforward network. Strong synaptic connections were observed only between consecutive processing levels, whereas there was no indication for strong connections between elements of the same processing level. Both spike synchronization and rate covariations were increased among neurons on higher processing levels. We further investigated the consequences that correlations may have on the common estimates of neuronal variability. For example, rate covariations caused by strong synaptic coupling between two neurons may lead to an overestimation if the variability is measured trial by trial with respect to only single neurons. For the vast majority of cell pairs tested, however, no strong synaptic coupling could be demonstrated. Thus we could show that in most cases no serious errors are made if one determines variability by following the usual procedure on the basis of single-cell recordings.
Asunto(s)
Potenciales de Acción/fisiología , Vías Auditivas/citología , Vías Auditivas/fisiología , Saltamontes/fisiología , Neuronas/fisiología , Estimulación Acústica/métodos , Animales , Percepción Auditiva/fisiología , Relación Dosis-Respuesta en la Radiación , Estimulación Eléctrica/métodos , Saltamontes/anatomía & histología , Modelos NeurológicosRESUMEN
When performing foraging trips desert ants of the genus Cataglyphis continuously process and update a ;home vector' that enables them to return to their nest on the shortest route. This capacity of path integration requires two types of information: (i) information about the travelling directions, and (ii) odometric information about the distances travelled in a particular direction. We have investigated how these two necessary pieces of information interact within the path integration processor. The specific question is: how do the ants process distance information if there is no simultaneous input from the sky compass available. Ants were trained to forage in a ;Z'-shaped channel system, the three segments of which joined at right angles. Individual animals were transferred from the feeder to a test field where their homing paths could be observed. In the crucial tests the middle segment of the maze was covered by orange Perspex that did not transmit the UV part of the spectrum, and thus precluded the perception of polarization patterns. Changes of the ant's processing of odometric information within this channel segment directly translate into a change in homing direction on the test field. The results indicate that the odometric information about travelling distance is largely ignored for path integration if there is no simultaneous input from the sky-view-based compass. They further show that idiothetic information cannot adequately substitute for the polarization compass to infer travelling directions.
Asunto(s)
Hormigas/fisiología , Conducta Apetitiva/fisiología , Locomoción/fisiología , Orientación/fisiología , Percepción Espacial/fisiología , Animales , Clima Desértico , TúnezRESUMEN
A key problem for neuronal information processing is the variability of spike trains, something that is likely to constrain the encoding of sensory signals. We measured interspike-interval variability (coefficient of variation) as well as spike-count variability (Fano factor) in the metathoracic auditory system of locusts. We performed simultaneous intracellular recordings at the first three processing levels to establish identical physiological conditions. This allows us to assess whether variability is generated anew or is reduced during synaptic transmission and processing. Both the interspike-interval variability as well as the spike-count variability revealed similar trends and showed an increase from the periphery to higher processing levels. This result was confirmed by single-cell recordings. A comparison of ascending interneurons coding for sound direction and those encoding sound patterns showed that the latter respond more reliably to repeated stimulus presentations. In general, the variability of spiking responses was much lower than expected from a Poisson process. Furthermore, we observed a strong dependence of variability on the spike rate, which differed at the three levels investigated. The differences in spike rates account for most of the differences in variability observed between processing levels. For auditory receptors, we found a good agreement between the Fano factor and the squared coefficient of variation, suggesting similarities to a renewal process of spike generation at the periphery. At the level of interneurons, the Fano factor was lower than the squared coefficient of variation; this indicates a higher reliability than expected from the interspike-interval distribution.
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Potenciales de Acción/fisiología , Vías Auditivas/fisiología , Encéfalo/citología , Neuronas/fisiología , Estimulación Acústica/métodos , Animales , Relación Dosis-Respuesta en la Radiación , Femenino , Saltamontes , Masculino , Modelos Neurológicos , Inhibición Neural/fisiología , Neuronas/clasificación , Tiempo de Reacción/fisiología , Localización de Sonidos/fisiología , Factores de TiempoRESUMEN
The recognition of the temporal structure of sound patterns by grasshopper males was investigated in behavioural experiments. Males were tested with short (165-335 ms) song models in which the characteristic subunit pattern of syllables and pauses was modified either at the beginning or at the end of the stimuli. The highly specific responses of the animals indicate that neuronal adaptation has a substantial influence on the detection of the pauses which are essential cues for the subunit structure: pauses were less likely detected shortly after the beginning of a song model than at later positions. Even adaptation in auditory neurons that was induced by unspecific stimulation (with unmodulated noise) facilitated the processing of sound envelopes. The effects of stimulus prolongation and introduction of pauses appeared to combine linearly, similar to the effects of introducing two pauses instead of a single one. In the responses to some song models large interindividual differences were observed. Comparison across stimuli and repeated testing of a smaller number of individuals indicated a considerable consistency of behavioural preferences. However, the data yielded no clear evidence for the existence of individually distinct processing types among males, that conceivably would focus on different features of the stimuli.
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Adaptación Fisiológica/fisiología , Comunicación Animal , Saltamontes/fisiología , Modelos Neurológicos , Neuronas/fisiología , Reconocimiento de Normas Patrones Automatizadas , Estimulación Acústica/métodos , Animales , Conducta Animal , Potenciales Evocados Auditivos , Extremidades/fisiología , Femenino , Masculino , Movimiento/fisiología , Ruido , Tiempo de Reacción , Detección de Señal Psicológica , Factores de Tiempo , Vocalización AnimalRESUMEN
Object recognition and classification by sensory pathways is rooted in spike trains provided by sensory neurons. Nervous systems had to evolve mechanisms to extract information about relevant object properties, and to separate these from spurious features. In this review, problems caused by spike train variability and counterstrategies are exemplified for the processing of acoustic signals in orthopteran insects. Due to size limitations of their nervous system we expect to find solutions that are stripped to the computational basics. A key feature of auditory systems is temporal resolution, which is likely limited by spike train variability. Basic strategies to reduce such variability are to integrate over time, or to average across several neurons. The first strategy is constrained by its possible interference with temporal resolution. Grasshoppers do not seem to explore temporal integration much, in spite of the repetitive structure of their songs, which invites for 'multiple looks' at the signal. The benefits of averaging across neurons depend on uncorrelated responses, a factor that may be crucial for the performance and evolution of small nervous systems. In spite of spike train variability the temporal information necessary for the recognition of conspecifics is preserved to a remarkable degree in the auditory pathway.
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Acústica , Potenciales de Acción/fisiología , Vías Auditivas/fisiología , Neuronas Aferentes/fisiología , Estimulación Acústica/métodos , Comunicación Animal , Animales , Vías Auditivas/citología , Conducta Animal , Señales (Psicología) , Discriminación en Psicología/fisiología , Extremidades/fisiología , Saltamontes , Modelos Neurológicos , Movimiento/fisiología , Umbral Sensorial/fisiología , Detección de Señal Psicológica , TemperaturaRESUMEN
The detection of acoustic communication signals in the presence of sinusoidally amplitude modulated noise was investigated in males of the grasshopper Chorthippus biguttulus. The auditory system of grasshoppers exhibits only poor spectral resolution. Hence, these animals are ideally suited to investigate noise tolerance in a system operating in the temporal domain. As a sensitive indicator for signal recognition the conspicuous phonotactic turning responses of males were recorded. The main result was that noise modulated at low frequencies (1.5-5 Hz) did not impair recognition compared to a unmodulated noise. With long stimuli even a moderate improvement of noise tolerance was observed, an effect that can probably be attributed to the existence of long troughs at low modulation frequencies during which the masking of the signal was reduced. Higher modulation frequencies (15-150 Hz), however, rendered detection and recognition increasingly difficult, due to a strong interference of the sound pulses of the masking noise with the syllable-pause structure of the species-specific signals. There are no indications for the operation of mechanisms analogous to comodulation masking release as found in vertebrates, nor for a spatial release from masking.
Asunto(s)
Estimulación Acústica/métodos , Comunicación Animal , Saltamontes/fisiología , Ruido , Reconocimiento en Psicología/fisiología , Animales , Femenino , MasculinoRESUMEN
The temporal resolution of auditory receptors of locusts was investigated by applying noise stimuli with sinusoidal amplitude modulations and by computing temporal modulation transfer functions. These transfer functions showed mostly bandpass characteristics, which are rarely found in other species at the level of receptors. From the upper cut-off frequencies of the modulation transfer functions the minimum integration times were calculated. Minimum integration times showed no significant correlation to the receptor spike rates but depended strongly on the body temperature. At 20 degrees C the average minimum integration time was 1.7 ms, dropping to 0.95 ms at 30 degrees C. The values found in this study correspond well to the range of minimum integration times found in birds and mammals. Gap detection is another standard paradigm to investigate temporal resolution. In locusts and other grasshoppers application of this paradigm yielded values of the minimum detectable gap widths that are approximately twice as large than the minimum integration times reported here.
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Percepción Auditiva/fisiología , Potenciales Evocados Auditivos/fisiología , Saltamontes/fisiología , Células Receptoras Sensoriales/fisiología , Estimulación Acústica , Animales , Frío , Electrofisiología , Ganglios de Invertebrados/fisiología , CalorRESUMEN
The vast majority of animals are poikilotherms, and thus face the problem that the temperature of their nervous systems rather smoothly follows the temperature changes imposed by their environment. Since basic properties of nerve cells, e.g., the time constants of ion channels, strongly depend on temperature, a temperature shift likely affects the processing of the temporal structure of sensory stimuli. This can be critical in acoustic communication systems in which time patterns of signals are decisive for recognition by the receiver. We investigated the temperature dependence of the responses of locust auditory receptors and interneurons by varying the temperature of the experimental animals during intracellular recordings. The resolution of fast amplitude modulations of acoustic signals was determined in a gap detection paradigm. In auditory receptors and local (second order) interneurons, temporal resolution was improved at higher temperatures. This gain could be attributed to a higher precision of spike timing. In a third-order neuron, a rise in temperature affected the interactions of inhibition and excitation in a complex manner, also resulting in a better resolution of gaps in the millisecond range.
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Vías Auditivas/fisiología , Umbral Auditivo/fisiología , Saltamontes/fisiología , Neuronas Aferentes/fisiología , Estimulación Acústica , Potenciales de Acción/fisiología , Animales , Femenino , Masculino , Periodicidad , Tiempo de Reacción , Transducción de Señal , Transmisión Sináptica/fisiología , TemperaturaRESUMEN
Desert ants of the genus Cataglyphis perform large-scale foraging excursions from which they return to their nest by path integration. They do so by integrating courses steered and the distances travelled into a continually updated home vector. While it is known that the angular orientation is based on skylight cues, it still is largely enigmatic how the ants measure distances travelled. We extended the ants' task into the third dimension by training them to walk within an array of uphill and downhill channels, and later testing them on flat terrain, or vice versa. In these tests the ants indicated homing distances that did not correspond to the distances actually travelled, but to the ground distances; that is, to the sum of the horizontal projections of the uphill and downhill segments of the ants' paths. These results suggest a much more sophisticated mechanism of distance estimation than hitherto thought. The ants must be able to measure the slopes of undulating terrain and to integrate this information into their "odometer" for the distance estimation process.
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Hormigas/fisiología , Percepción de Distancia/fisiología , Locomoción/fisiología , Orientación/fisiología , Animales , Señales (Psicología) , Clima Desértico , Metabolismo Energético/fisiología , Odorantes , Estadísticas no ParamétricasRESUMEN
Desert ants (Cataglyphis) are renowned for their ability to perform large-scale foraging excursions and then return to the nest by path integration. They do so by integrating courses steered and the distances travelled into a continually updated home vector. Whereas the angular orientation is based on skylight cues, how the ants gauge the distances travelled has remained largely unclear. Furthermore, almost all studies on path integration in Cataglyphis, as well as in spiders, rodents, and humans, have aimed at understanding how the animals compute homebound courses in the horizontal plane. Here, we investigate for the first time how an animal's odometer operates when a path integration task has to be accomplished that includes a vertical component. We trained Cataglyphis ants within arrays of uphill and downhill channels, and later tested them on flat terrain, or vice versa. In all these cases, the ants indicated homing distances that corresponded not to the distances actually travelled but to the ground distances; that is, to the sum of the horizontal projections of the uphill and downhill segments of the ants' paths.
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Hormigas/fisiología , África del Norte , Animales , Conducta Animal , Clima Desértico , Percepción de Distancia/fisiología , LocomociónRESUMEN
Despite their simple auditory systems, some insect species recognize certain temporal aspects of acoustic stimuli with an acuity equal to that of vertebrates; however, the underlying neural mechanisms and coding schemes are only partially understood. In this study, we analyze the response characteristics of the peripheral auditory system of grasshoppers with special emphasis on the representation of species-specific communication signals. We use both natural calling songs and artificial random stimuli designed to focus on two low-order statistical properties of the songs: their typical time scales and the distribution of their modulation amplitudes. Based on stimulus reconstruction techniques and quantified within an information-theoretic framework, our data show that artificial stimuli with typical time scales of >40 msec can be read from single spike trains with high accuracy. Faster stimulus variations can be reconstructed only for behaviorally relevant amplitude distributions. The highest rates of information transmission (180 bits/sec) and the highest coding efficiencies (40%) are obtained for stimuli that capture both the time scales and amplitude distributions of natural songs. Use of multiple spike trains significantly improves the reconstruction of stimuli that vary on time scales <40 msec or feature amplitude distributions as occur when several grasshopper songs overlap. Signal-to-noise ratios obtained from the reconstructions of natural songs do not exceed those obtained from artificial stimuli with the same low-order statistical properties. We conclude that auditory receptor neurons are optimized to extract both the time scales and the amplitude distribution of natural songs. They are not optimized, however, to extract higher-order statistical properties of the song-specific rhythmic patterns.
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Estimulación Acústica/métodos , Comunicación Animal , Vías Auditivas/fisiología , Neuronas Aferentes/fisiología , Células Receptoras Sensoriales/fisiología , Potenciales de Acción/fisiología , Animales , Femenino , Saltamontes , Masculino , Modelos Neurológicos , Periodicidad , Tiempo de Reacción/fisiología , Umbral Sensorial/fisiología , Procesamiento de Señales Asistido por Computador , Especificidad de la EspecieRESUMEN
The formation of complexes between the minor receptor group human rhinovirus HRV2 and two recombinant soluble receptor fragments derived from the human very low density lipoprotein receptor (VLDLR) and containing ligand-binding repeats 1-3 (MBP.VLDLR(1-3)) or 1-8 (MBP.VLDLR(1-8)) fused to the carboxyl terminus of the maltose-binding protein was analyzed by affinity capillary electrophoresis. At low molar ratios of receptor/virus, the peaks corresponding to substoichiometric complexes were broad indicating heterogeneity. When the receptors were present in molar excess with respect to the virus, the peaks were sharp, suggesting saturation of all binding sites. For the determination of the stoichiometry, constant amounts of receptor were incubated with increasing amounts of virus, and the peak areas corresponding to free receptor were measured and plotted versus total virus concentration. Extrapolation of the linear part of the resulting curve to zero concentration of free receptor enabled quantitation of the molar ratios of the components present in the complex. Using this method, we determined that about 60 molecules of MBP.VLDLR(1-3) but only about 30 molecules of MBP.VLDLR(1-8) were bound per virion.
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Receptores de LDL/química , Receptores de LDL/metabolismo , Rhinovirus/metabolismo , Sitios de Unión , Proteínas Portadoras/metabolismo , Electroforesis Capilar/métodos , Humanos , Cinética , Lipoproteínas VLDL/metabolismo , Proteínas de Unión a Maltosa , Receptores de LDL/genética , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Rhinovirus/clasificación , Rhinovirus/genéticaRESUMEN
Minor group human rhinoviruses (HRVs) use members of the low-density lipoprotein receptor family for cell entry. To investigate the utility of receptor fragments as viral inhibitors, various polypeptide segments derived from the ligand binding domain of human very-low-density lipoprotein receptor (VLDLR) were expressed in a soluble form in bacteria. Whereas none of the fragments was active in virus binding immediately after recovery from the cell lysates, constructs encompassing complement type repeats 1-3, 1-6, and 1-8 spontaneously acquired virus binding activity by incubation at 4 degrees C in buffer containing Ca(2+) ions and lacking any redox system. When immobilized receptor-associated protein (RAP), a specific chaperone for VLDLR, was present during the incubation, the yield of protein active in ligand binding was substantially increased. A VLDLR fragment with repeats 4-6 failed to bind virus; however, it bound RAP. Bacterial expression of truncated VLDLR 1-3 at high yield, easy purification, and folding together with high inhibitory activity toward HRV2 makes this protein a promising starting point for the development of an oligopeptide-based antiviral agent. Using sucrose density gradient centrifugation, we demonstrate the formation of virus-receptor complexes. The recombinant receptors can thus be used for structure determination by electron cryo-microscopy.
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Pliegue de Proteína , Receptores de LDL/fisiología , Receptores Virales/fisiología , Rhinovirus/fisiología , Sitios de Unión , Clonación Molecular , Cartilla de ADN , Humanos , Modelos Moleculares , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Conformación Proteica , Receptores de LDL/química , Receptores de LDL/genética , Receptores Virales/química , Receptores Virales/genética , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismoRESUMEN
Human rhinovirus serotype 2 (HRV2) belongs to the minor group of HRVs that bind to members of the LDL-receptor family including the very low density lipoprotein (VLDL)-receptor (VLDL-R). We have determined the structures of the complex between HRV2 and soluble fragments of the VLDL-R to 15 A resolution by cryo-electron microscopy. The receptor fragments, which include the first three ligand-binding repeats of the VLDL-R (V1-3), bind to the small star-shaped dome on the icosahedral 5-fold axis. This is in sharp contrast to the major group of HRVs where the receptor site for ICAM-1 is located at the base of a depression around each 5-fold axis. Homology models of the three domains of V1-3 were used to explore the virus-receptor interaction. The footprint of VLDL-R on the viral surface covers the BC- and HI-loops on VP1.
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Rhinovirus/química , Rhinovirus/metabolismo , Secuencia de Aminoácidos , Sitios de Unión , Microscopía por Crioelectrón , Cristalografía por Rayos X , Células HeLa , Humanos , Molécula 1 de Adhesión Intercelular/química , Ligandos , Modelos Moleculares , Datos de Secuencia Molecular , Mutagénesis , Unión Proteica , Estructura Terciaria de Proteína , Receptores de LDL/química , Receptores Virales/química , Proteínas Recombinantes/química , Homología de Secuencia de AminoácidoRESUMEN
Currently two hypotheses exist as to how insects process visual images, as photograph-like 'retinotopic-templates', or as a set of features extracted by the visual system. Several results obtained in honeybees cannot be reconciled with a retinotopic-template matching. (i) Bees discriminated between two patterns that should not be distinguished according to the template hypothesis. (ii) Bees preferred patterns that showed no overlap with the assumed template to patterns that had such an overlap. (iii) Bees showed a generalization of properties of the rewarded pattern to other patterns. Thus, in our paradigm, the bees must have used additional mechanisms and cues for the processing and classification of patterns.
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Abejas/fisiología , Imagen Eidética/fisiología , Reconocimiento Visual de Modelos/fisiología , Animales , Señales (Psicología)RESUMEN
The formation of complexes of human rhinovirus (serotype HRV2 and HRV14) with nonaggregating neutralizing monoclonal antibodies was investigated by affinity capillary electrophoresis. The method is based on preincubation of virus with antibody, followed by CE analysis. At low antibody-to-virus ratios, peaks corresponding to the complexes were broad, pointing to the presence of a heterogeneous population of virions with various numbers of antibodies bound; at a high molar ratio between virus and antibody, the peak became narrow again, indicating saturation of the 60 equivalent viral epitopes with the antibodies being attached bivalently. As SDS was used as an additive in the background electrolyte to allow for separation, its influence on complex formation was investigated. Once formed, HRV2-antibody complexes were found to be stable in the presence of the detergent but complex formation in buffer containing SDS was severely impaired. HRV14-antibody complexes were rapidly dissociated by SDS. The method proved to be useful for a rapid assessment of complex formation and might allow for an estimation of the binding stoichiometry.
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Anticuerpos Monoclonales/inmunología , Rhinovirus/inmunología , Electroforesis Capilar , Humanos , Dodecil Sulfato de Sodio/farmacologíaRESUMEN
The behaviour of many animals indicates a high precision in the processing of sensory signals, which often seems at odds with the large variability of individual neuronal responses. Using the directional hearing of the grasshopper Chorthippus biguttulus (Ch. biguttulus) as a model system, we investigated the possible contributions of temporal integration and parallel processing at the receptor level to the observed behavioural acuity. The precision of the animals' phonotactic orientation behaviour to stimuli of different durations was measured and compared with the spiking responses of auditory receptor cells, leading to the following results. A behavioural decision based on integrating the spikes from a pair of receptors (one cell in each ear) over a 1000-ms time window would substantially decrease the error probability, compared with evaluating a 250-ms period. The animal as a whole, however, responded as precisely to a 250 ms stimulus as to a stimulus of natural duration (c. 1000 ms). A phonotactic decision based on a 1.5 dB intensity difference between the ears corresponds to a spike count difference of approximately 1 spike per 100 ms in a pair of receptors. As these differences are in the order of the statistical spike count fluctuations, the error probabilities for an ideal observer of the spike count are substantially higher (13-18%) than the errors observed in the behavioural tests (only 5%). We conclude that the animals' nervous system has to sample information from a pool of 6-13 receptors to arrive at the observed behavioural precision.
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Saltamontes/fisiología , Audición/fisiología , Neuronas Aferentes/fisiología , Localización de Sonidos/fisiología , Potenciales de Acción/fisiología , Animales , Percepción Auditiva/fisiología , Electrofisiología , Masculino , Método de Montecarlo , Tiempo de Reacción/fisiologíaRESUMEN
Differentiation of virus serotypes with capillary zone electrophoresis was demonstrated. For four serotypes of human rhinovirus (HRV2, HRV14, HRV16, HRV49), different electrophoretic mobility was achieved at pH 8.3 (borate/boric acid buffer, 100 mmol/L). Addition of detergent (Triton X-100-R, deoxycholate, and/or SDS) to the background electrolyte was required for reduction of wall adsorption and improvement of peak shape. A major nonviral contaminant, present in all virus samples, was best separated from the viral peaks with 10 mmol/L SDS as additive. The method allowed detecting serotypes HRV16 and HRV49 in crude, partially purified virus preparations. An infectivity assay carried out off-line with fractions collected at the capillary outlet enabled the sensitive and biospecific identification of the peaks of HRV2 and HRV14.