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1.
1.  The cross-adapting effects of chemical backgrounds on the response of primary chemoreceptor cells to superimposed stimuli were studied using NH4 receptor cells, of known spectral tuning, from the lobster (Homarus americanus).
2.  Spectrum experiments: The spectral tuning of NH4 receptor cells was investigated using NH4Cl and 7 other compounds selected as the most stimulatory non-best compounds for NH4 cells from a longer list of compounds tested in previous studies. Based on their responses to the compounds tested, 3 spectral subpopulations of NH4 cells were revealed: NH4-Glu cells which responded second-best to Glutamate (Glu); NH4- Bet cells which responded second-best to Betaine (Bet); and pure NH4 cells, which responded to NH4C1 only (Fig. 1).
3.  Cross-adaptation experiments: Overall, cross-adaptation with Glu and Bet backgrounds caused suppression of response of NH4 receptor cells to various concentrations of NH4Cl. However, the different subpopulations of NH4 cells were affected differently: (a) The stimulus-response functions of NH4-Glu cells were significantly suppressed by both a 3 M (G3) and 300 M (G300) Glu backgrounds, (b) The stimulus-response functions of NH4-Bet cells was not affected by a 3 M (B3), but significantly suppressed by a 300M (B300) Bet background. (c) The stimulus-response functions of pure NH4 cells were not affected by any of the Glu or Bet backgrounds (Figs. 3, 4).
4.  The stimulus-response functions of 5 cells from all different subpopulations were enhanced by cross-adaptation with the G300 and B300 backgrounds (Fig. 4, Table 1).
5.  Whereas self-adaptation caused parallel shifts in stimulus-response functions (Borroni and Atema 1988), cross-adaptation caused a decrease in slope of stimulus-response functions. Implications of the results from cross- and self-adaptation experiments on NH4 receptor cells, for a receptor cell model are discussed.
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2.
1.  To determine reliability of stimulus intensity coding we measured the response variability of 30 hydroxy-L-proline sensitive chemoreceptor cells from antennules of Homarus americanus. First, cells were tested with 5 repeated presentations of 10-5 M and l0-4 M hydroxy-L-proline. Then a stimulus response function was determined in each cell from l0-6to 5 × l0-4 M in half log steps.
2.  Population mean responses to repetitive stimulation showed little variability and mean stimulus response functions increased monotonically. In contrast, most individual cells showed a high response variability and no single cell stimulus-response function increased monotonically. The greatest response variability occurred between different cells.
3.  Mean response magnitude of a 30 cell population allowed reliable discrimination between 10-5 M and l0-4 M hydroxy-L-proline for each of the 5 repetitions. It also allowed discrimination of all concentrations of hydroxy-L-proline tested. Across-fiber response patterns also differed significantly with concentration while they remained relatively stable with repetition of the same stimulus.
4.  We applied different analytical methods to test the reliability of response magnitude and across-fiber pattern as possible codes for intensity discrimination. We demonstrated that a random population of rather unreliable receptor cells could provide remarkably reliable intensity information to the CNS based on response magnitude or across-fiber pattern.
Dedicated to the memory of Vincent Dethier, who pioneered several of the questions addressed in this study.  相似文献   

3.
1.  Non-visual sensory systems are likely to be important in antarctic fish since these fish inhabit an area where low light levels occur for long periods. This study was undertaken to examine the suitability of the lateral line system for prey detection.
2.  Recordings were made from afferent fibres of the anterior lateral line in the antarctic fishPagothenia borchgrevinki.
3.  A vibrating probe was used to stimulate the lateral line at a range of frequencies between 10 and 100 Hz.
4.  Most units responded best at a stimulus frequency of 40 Hz. Below the best frequency the response typically declined steeply and at higher frequencies it was usually better sustained.
5.  Crustacea identified as major components of the diet ofPagothenia borchgrevinki were individually attached to a force transducer to determine the vibrations produced by swimming movements.
6.  The Fourier amplitude spectra of swimming crustaceans exhibited prominent low frequency peaks at 3–6 Hz and higher frequency peaks in the 30–40 Hz range.
7.  It is concluded that the overlap in the frequency response characteristics of the anterior lateral line and the frequencies produced by crustacean prey clearly establishes the suitability of the lateral line for prey detection.
8.  In several instances recordings were made from fish primary afferent neurons responding to a swimming amphipod. These recordings confirm that crustacean swimming is indeed a potent natural stimulus of the lateral line system.
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4.
1.  The excitatory and inhibitory influences on the gill ofAplysia Juliana, which are mediated by the branchial nerve, were studied by means of electrophysiological techniques. Excitatory and inhibitory pathways in the nerve were stimulated simultaneously or selectively.
2.  The branchial nerve was found to contain both excitatory and inhibitory pathways which did not contain synapses in the branchial ganglion. The excitatory pathways caused longitudinal shortening of the gill along the efferent branchial vessel and the inhibitory pathways were modulatory, depressing the longitudinal shortening.
3.  Branchial nerve stimulation elicited two types of excitatory junctional potential (EJP), which were not mediated by the branchial ganglion, in a muscle cell of the efferent branchial vessel. One type was attributed to the central motor neuron and the other type to a motor neuron which is probably situated in the neural plexus of the gill periphery.
4.  Four inhibitory pathways from the central nervous system to the gill were found.
5.  Inhibitory junctional potentials (IJPs) recorded from muscle cells of the efferent branchial vessel in response to branchial nerve stimulation did not have monosynaptic characteristics. It is thought that inhibitory motor neurons which were activated by the branchial nerve might exist at the neural plexus of the gill.
6.  A single EJP which has been induced by a stimulus pulse applied to the excitatory pathway of the branchial nerve may be depressed in an all-or-none manner by a stimulus pulse applied to the inhibitory pathway, if this is done within a distinct short period prior to or after the stimulus inducing the EJP. This indicates that the central motor neuron receives presynaptic inhibition at its periphery.
7.  The motor neurons of the neural plexus seem to receive inhibitory innervation. Suppression of endogenous EJPs in the efferent vessel persisted for a long period even after cessation of stimulation.
8.  A certain branchioganglionic neuron (BGN) was found to receive inhibitory postsynaptic potential (IPSP) inputs from the branchial nerve.
9.  The multimodality of both the excitatory and the inhibitory pathways in the branchial nerve may explain the compound neural modulations of gill movements.
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5.
Ipsilateral retino-tecto-tectal (IRTT) units were recorded extracellularly in the rostral optic tectum of the frog (Rana esculenta). The activity of 79 superficial units (II type) was quantified in response to black disks of various sizes, moved vertically at various angular velocities and against a white background. The contrast ¦C¦ was constant during the experiments. Neuronal activity was analysed by two methods, yielding identical results:
(1)  I1 units responded transiently to moving and movement gated stationary stimuli; these units did not seem to be directionally sensitive nor responsive to changes in background illumination. Fifty-three % of units had a low spontaneous activity.
(2)  A power function relating mean firing frequency (¯R) and angular velocity (v) was established in the majority (78%) of units. The exponent and the constantk were 0.44–0.8 and 8.9–20, respectively.
(3)  The relationship between¯R and stimulus diameter (D) was best expressed by a logarithmic function. The maximum response occurred forD= 2–4. The optimal stimulus diameter was found to be independent of stimulus velocity.
(4)  When stimulated repetitively under steady conditions, I1 units showed about 10% fluctuations in mean response, which seemed to increase with stimulus diameter.
The results show that qualitatively and quantitatively, the properties of I1 units are very similar to R1–R2 (sustained) ganglion cells.  相似文献   

6.
1.  The activity of tympanal high- and low-frequency receptors in the migratory locustLocusta migratoria was recorded with glass capillary microelectrodes, and Lucifer Yellow was then injected through the microelectrode to reveal the cells' metathoracic projections.
2.  A photodetector device was used to monitor the abdominal respiratory movements, which caused clearly visible deflections of the tympanal membrane.
3.  The auditory receptors respond not only to sound stimuli but also to the respiratory movements; these phasic (Figs. 1–3) or tonic (Fig. 4) responses are especially pronounced during the inspiration and expiration movements, and less so during the constriction phases.
4.  The magnitude of the response to sound depends on the phase of the stimulus with respect to the respiratory movements. At certain phases sound elicits no response at all (Fig. 5).
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7.
1.  We determined the spectral tuning properties of 47 chemoreceptor cells of the antenna of Homarus americanus to amino acids and other compounds. Tests with 17 single compounds at 10-4 M showed 40 of 47 cells responded best to hydroxyproline, 4 cells to taurine and 3 cells to betaine. Mean tuning breadth (H-metric) doubled with 10 fold increase in concentration.
2.  In hydroxyproline-best cells the mean threshold for hydroxyproline (Hyp) was found between 10-7 M and 10-8 M. An equimolar mixture of the 17 compounds generated a shallower stimulus-response function with thresholds similar to Hyp function (mixture suppression). Hyp-best cells were relatively narrowly tuned, often with arginine or leucine as second best stimuli.
3.  Thus, physiologically the second antenna of H. americanus is a major chemoreceptor organ. It is more than any of the 5 chemoreceptor organs studied so far dominated by a single best-cell type (Hyp). Receptor cell composition of antennae resembles that of antennules more than legs or maxillipeds. Hyp-best cells in antennae and lateral antennules have similar tuning spectra.
4.  Our cell tuning studies argue for independent receptors for all amino acids tested. We conclude that diversity of receptor cell tuning is created by cell-specific blends of receptors. At the organ level, differences in organ tuning result from different blends of receptor cells.
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8.
1.  Some properties of the open-tipped, uninsulated, pH-sensitive glass microelectrode were examined in several electrical experiments.
2.  Based on these observations, technical and theoretical problems were considered for application to the pH measurement in small cells.
3.  The intracellular pH, (pH)i, of the epithelial cell in rat duodenum measured was approximately 7.0. A reduction in (pH)i was apparent (about 0.3) with the addition of 20 mM-glucose to the bathing fluid.
4.  It was concluded, that with certain limitations such uninsulated, open-tipped microelectrodes may be successfully utilized for intracellular pH measurements.
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9.
1.  The actions of GABA on three classes of visual interneurons in crayfish, Procambarus clarkii, medulla externa are examined. The effect of GABA on the visual response is compared to GABA's action on agonist-elicited responses purported to mediate the visual response.
2.  GABA produces a shunting type of inhibition in medullary amacrine cells which is associated with a small depolarization (Figs. 2, 3), a large increase in input conductance (Gn) and a reversal potential close to rest (Fig. 4). GABA is a potent antagonist to the depolarizing action of acetylcholine (ACh) (Fig. 5).
3.  GABA depolarizes dimming fibers (Fig. 2), and the response is mediated by an increase in Gn (Fig. 6). GABA antagonizes the light-elicited IPSP and the hyperpolarizing action of ACh (Fig. 7).
4.  Sustaining fibers (SF) do not appear to have GABA receptors but GABA inhibits the excitatory visual input pathway to the SFs (Fig. 8). Conversely, the GABA antagonist, bicuculline, potentiates the SF light response (Fig. 9).
5.  GABA has at least three different modes of antagonist action in the medulla: i) Increased conductance and depolarization in dimming fibers and medullary amacrine neurons; ii) Decreased chloride conductance in tangential cells; and iii) An inhibitory action on the visual pathway which drives SFs.
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10.
1.  The reactions of tympanic nerve fibers ofLocusta migratoria were recorded by glass microelectrodes in the metathoracic ganglion.
2.  The units were classified by frequency-, intensity-, and directional characteristics as well as by their response pattern. The response to speciesspecific song is compared with the response to song ofEphippiger ephippiger.
3.  The physiological properties lead to a classification into three types of low-frequency neurons (characteristic frequency 3.5–4 kHz; 4kHz; 5.5–6 kHz) and one type of high-frequency neuron (12–20 kHz). This is similar to other species (Gray, 1960, Michelsen, 1971).
4.  Intensity-coding is done by sharp rising intensity characteristics and by different absolute thresholds of the units.
5.  There is a marked directional sensitivity with some differences between LF and HF units. In the low frequency range the tympanal organ seems to react as a pressure gradient receiver; for high frequencies another mechanism is discussed.
6.  No filtering of species-specific song takes place at the level of the receptor cells.
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11.
Twelve of the main European LCA software packages currently available are examined wirh the aim of establishing which are the most appropriate for LCAs on industrial processes. The packages performances are assessed in terms of
–  • Volume of Data
–  • WindowsTM environment
–  • Network Capabilities
–  • Impact Assessment
–  • Graphical representation of the inventory results
–  • Sensitivity analysis
–  • Units
–  • Cost
–  • User Support
–  • Flow Diagrams
–  • Burdens allocation
–  • Transparency of data
–  • Input & output parameters
–  • Demo version
–  • Quality of data
The review concludes with a Specification Table which summarises the facilities available on each software package. The general conclusion from this study is that for industrially based LCAs, there are four packages which may offer advantages over the rest. These are The Boustead Model, The Ecobilan Group’s TEAM™, PEMS 3.0 and SimaPro 3.1.  相似文献   

12.
Intracellular recordings have been made of responses to step, ramp and sinusoidal changes of light by second-order L-neurones and a third-order neurone, DNI, of locust (Locusta migratoria) ocelli.
1.  The membrane potential at the peak response by an L-neurone to a change in light is proportional to the light increment or decrement, independent of background, over a range of at least 4 log units. As background increases, response latency and time-course decrease, and responses become more phasic (Fig. 1).
2.  Adaptation to a changed mean light level involves a change in sensitivity and a slow change in resting membrane potential, which never adapts completely to dark resting potential in the presence of light (Fig. 3).
3.  L-neurones can follow changes in light which last several seconds, but responses to fast changes are enhanced in amplitude (Figs. 4, 5). An increase in background light causes an increase in the frequency of sinusoidally modulated light at which the largest response occurs (Fig. 4).
4.  The responses of DNI to increased light saturate at lower intensities than those of L-neurones. During adaptation to different background light intensities, there is no change in the input-output relation of the synapse between an L-neurone and DNI (Figs. 6, 7).
5.  For a rapid decrease in light, DNI produces a rebound spike, followed by a period of silence (Figs. 5, 8).
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13.
In a task designed to simulate olfactory-guided foraging, the ability of squirrel monkeys to discriminate an artificial 12-component odorant from 3-, 6-, 9- or 11- component submixtures was investigated. A combination of factors was found to contribute to the animals' performance:
1.  Discriminability generally decreased as the number of components in the submixture increased.
2  Submixtures did not contribute equally to mixture perception, and one component in particular (cineole) disproportionately influenced stimulus discriminability.
3.  Interactive effects between submixtures resulted in marked deviations from the general pattern of discriminability.
4.  Changes in the relative concentration of submixtures could also influence discriminability.
5.  Finally, individual differences in responsiveness to particular stimuli were apparent.
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14.
1.  Direct contact between intra-epithelial nerve endings and ciliated cells was observed in frog (Rana pipiens) palate epithelium.
2.  Electrical stimulation of the palatine nerve to the explant or the explant culture induced an increase in ciliary beat frequency in explant and outgrowth cells.
3.  Atropine inhibited electrically stimulated ciliary beat frequency increase in the explant and outgrowth cells.
4.  Gap junctional intercellular communication appears to be involved in the propagation of stimulated ciliary beat frequency increase from innervated to non-innervated ciliated cells.
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15.
1.  Tethered flies (Musca domestica) walking on an air-suspended ball show a spontaneous response to the e-vector of polarized light presented from above, i.e. a slowly rotating e-vector induces periodic changes in the flies' turning tendency. Suitable control experiments exclude the possibility that the response is elicited by intensity gradients in the stimulus (Figs. 1 and 2).
2.  Presence of the e-vector response in both white and UV light and its complete absence in yellow light equally support the concept that the specialized dorsal rim area of the compound eye with its highly polarization sensitive UV receptors R7marg and R8marg mediates polarization vision in flies (Fig. 3).
3.  E-vector orientations inducing no turning response additional to the fly's inherent turning tendency are either parallel (avoided e-vector) or perpendicular (preferred e-vector) to the animal's body axis (Figs. 1 and 4).
4.  Considering the fanlike arrangement of the microvillar orientations of R7marg and R8marg in the dorsal rim area of the eye of Calliphora and Musca, a stabilizing function of polarization vision in controlling the flight course is suggested and discussed in the context of results from other behavioural studies.
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16.
1.  We used laser vibrometry and free field sound stimulation to study the frequency responses of the eardrum and the lateral body wall of awake male Eleutherodactylus coqui.
2.  The eardrum snowed one of two distinct frequency responses depending on whether the glottis was open (GO response) or closed (GC response) during the measurement.
3.  The lateral body wall vibrated with a maximum amplitude close to that of the eardrum and in the same frequency range.
4.  Covering the frog's body wall with vaseline reduced the vibration amplitude of the GC response by up to 15 dB.
5.  When a closed sound delivery system was used to stimulate a local area of the body wall the eardrum also showed one of two types of responses.
6.  These results suggest that sound is transmitted via the lung cavity to the internal surface of the eardrum. This lung input has a significant influence on the vibrations of the eardrum even when the glottis is closed.
7.  The vibration amplitude of the eardrum changed with the angle of sound incidence. The directionality was most pronounced in a narrow frequency range between the two main frequencies of the conspecific advertisement call.
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17.
J. Robb 《Human Evolution》1994,9(3):215-229
In recent years anthropologists have made much progress in understanding ancient activities from skeletal remains. In this paper, material from the Iron Age cemetery at Pontecagnano (VII-IV century BC) is used to illustrate activity-related traits of eight basic categories:
(1)  idiosyncratic patterns of dental wear
(2)  activity-related articular degeneration
(3)  non-pathological functional alterations (neoformations, contact facets)
(4)  mechanical remodelling of bone architecture
(5)  enthesopathies (muscular lesions)
(6)  traumatic lesions
(7)  activity-related pathologies
(8)  activity-related nutritional characteristics
These traits, and others, can be used not only singly but in conjunction to define (a) patterns of activity and occupational specialization for individuals, and (b) distributions within society reflecting the basic division of labor by geneder and class.  相似文献   

18.
The caudal photoreceptors (CPRs) of crayfish (Procambarus clarkii) can trigger walking and abdominal movements by their response to light.
1.  In a restrained, inverted crayfish, illumination of A6 evoked a CPR discharge followed by leg movements and bursting from the abdominal tonic flexor (TF) motoneurons. Intracellular electrical stimulation of a single CPR at high frequency (80 Hz) evoked similar responses.
2.  Responses only occurred when a single CPR axon was driven at 60 Hz or more and outlasted the stimulus.
3.  CPR stimulation also excites the pattern-initiating network (Moore and Larimer 1987) in the abdomen.
4.  The axon of the CPR projects from ganglion A6 to the brain. Terminal branches occur in the subesophageal ganglion and the brain. A small descending interneuron is dye-coupled to CPR in the subesophageal ganglion.
5.  In animals with cut circumesophageal connectives, the CPRs can evoke walking and the abdominal motor pattern.
6.  The relationship of the abdominal motor pattern to walking is altered by restraint and/or inversion. In freely moving crayfish, the cyclic abdominal motor pattern is only observed with backward walking. In restrained, inverted crayfish, the motor pattern occurs with both forward or backward walking.
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19.
Temporal coding in the moth ear was inferred from the response of the auditory receptor to acoustic stimuli with different temporal characteristics.
1.  Determinations of the threshold with different stimulus pulse durations showed that the moth ear behaves as an energy detector with a maximum time constant (the integration time) of 25 ms. Pulse durations beyond this value did not result in decreased thresholds (Fig. 1).
2.  The synchronization to amplitude modulations was determined by stimulating the moth ear with amplitude modulated (AM) tones (carrier frequency: 40 kHz) and AM white noise presented as 450 ms pulses separated by pauses of similar length. The modulation depth was constant (100%) whereas the modulation frequency,f m, was varied. The maximumf m which the auditory receptors could follow was 200 Hz (P<0.05) (figs.=" 2,=" 3,=" 4).=">
3.  The relatively broad tuning of the only receptor which was functional at the relevant stimulus intensities suggested that AM detection could only be based on temporal cues. This was confirmed by the results showing the same degree of synchronization independent of carrier.
4.  A minimum time constant for the receptor was also determined by interrupting a 400 ms noise pulse by a gap (Figs. 5, 6). The threshold for gap detection of the moth ear was ca. 2 ms on a 2.5% significance level (one sided test).
5.  The temporal acuity reported here seems to be fine enough to explain the temporal resolution suggested by behavioral results from other insect species. The results are discussed in relation to acoustic communication in insects as well as in relation to temporal resolution in vertebrates.
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20.
1.  Seasonal changes in the half-times (0.5) for calcium influx and outflux in bone, skin and scales, and soft-tissue compartments ofF. kansae were measured.
2.  The size of diffusible calcium pools in the three compartments was estimated from the ratio of the loading and unloading half-times. Both the bone and skin and scales compartments contain diffusible calcium pools which increase in size during the summer months.
3.  The calcium in the soft-tissue compartment is all diffusible, and the kinetics indicate that this compartment receives calcium from the other two compartments.
4.  Hypophysectomy reduced the rate of calcium turnover in summer animals to the levels measured in intact winter animals. Such treatment also affected the distribution of radiocalcium within the animal.
5.  It is concluded that acellular bone is a metabolically active tissue.
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