ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    The Terminal Nerve of Sharks and Rays (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 519 (1987), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1987.tb36283.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Discrimination among temporal patterns of stimulation in a computer model of a coelenterate nerve net (1967)
    Springer
    Biological cybernetics 3 (1967), S. 240-249 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Summary A simulation study is reported of the spread of excitation in a digital computer model based quite realistically on a coelenterate nerve net. The question posed is whether an elementary nervous system with randomly distributed properties can discriminate between time patterns of stimuli at the same average frequency. Forty-four temporal patterns of stimulation, each composed of seven stimuli in the same total period of time were applied to each of nine simulated nerve nets with each of eleven different distributions of four rates of decay of facilitation. The results may be summarized as follows: 1. The simulated nerve nets used were able reliably to discriminate between many of the time patterns used. The factors entering into range and acuity of pattern discrimination by the net are identified. 2. The simulated nerve nets tended to support a greater spread of excitation in response to even temporal distribution of stimuli than in response to clustered distributions of stimuli under certain conditions. These conditions are specified. 3. The response measure which was used (“final spread”) is shown to give different results in some cases than either of two other measures (“average” spread for the seven stimuli and “maximum spread”). 4. The simulated nerve nets were able to produce reliable differences in the spread of excitation between certain patterns and their temporally mirror-image counterparts. The necessary conditions for such pattern recognition are described. The relationships among the principal variables, namely the temporal distribution of stimuli, the specific sequence of junction decay rates, the magnitudes of facilitation decay rates, and their relative frequency distributions are described as they affect the spread of excitation in the nerve net. The overall finding that the net is able to discriminate between some temporal patterns gathers significance in that it represents an ability of the net to translate temporally coded information into spatial form. Thus, it is shown that already at the level of a simplified model of a coelenterate nervous system, the requisites for temporal to spatial translation are met.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288554
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Comparison of the jamming avoidance responses in Gymnotoid and Gymnarchid electric fish: A case of convergent evolution of behavior and its sensory basis (1975)
    Springer
    Journal of comparative physiology 103 (1975), S. 97-121 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. A behavioral response conforming to defining features of the jamming avoidance response (JAR) previously reported inEigenmannia andApteronotus of the Cypriniformes is found inGymnarchus of the Mormyriformes. 2. Other parallel specializations of these groups are noted, of which the most relevant is the character of the electric organ discharge (EOD); it is quasisinusoidal, high in repetition rate and highly regular in each of the genera. The same features are found inSternopygus but it lacks a JAR. 3. The EOD is compared inGymnarchus, Eigenmannia, Apteronotus andSternopygus, in respect to power spectrum and regularity. 4. Other special features of the EOD inGymnarchus are described, including “singing” and a miniature EOD of a different frequency from the main EOD. 5. The JAR inGymnarchus, compared toEigenmannia andApteronotus is longer in latency, slower in reaching plateau, smaller in maximum frequency shift and best excited by a stimulus frequency closer to its own. The voltage gradient threshold (≪2.5μV/cm) is higher and the dynamic range smaller. Some correlations with habit of life are suggested. 6. Two types of electroreceptors seem particularly relevant to the JAR. They are similar to the T and P units already reported inEigenmannia but substantial differences require separate designations; we call them Type S and Type O units. 7. Type S units are like T units but spontaneous at high rates and phase coding over a limited intensity range near threshold. Over a wide range of intensity, including much of the physiological range normally encountered the S unit cannot encode intensity. 8. Type O units are like P units but usefully coding in a narrow intensity range; they are often unable to reach 1∶1 following. The threshold is usually about 20 db higher than in S units. 9. The filter properties of both types are those of a bandpass filter. Whereas the O units are sharply tuned to the EOD frequency, the S units have a flat passband over a range of about 150 Hz, and sharp cutoffs (about 50 db/octave) on both the high and low frequency sides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01380047
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Sensory evoked potentials in unanesthetized unrestrained cuttlefish: a new preparation for brain physiology in cephalopods (1991)
    Springer
    Journal of comparative physiology 168 (1991), S. 141-150 
    Details
    ISSN: 1432-1351
    Keywords: Event related potentials ; Visual evoked potentials ; Sepia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Up to five microelectrodes inserted through short hypodermic needles in the cranial cartilage of Sepia officinalis recorded potentials while the cuttlefish moved freely in a small enclosure. Compound field potentials and unit spikes were seen during ongoing, spontaneous activity and after sensory stimulation. Ongoing activity resembles that reported for octopus, with maximum power usually below 20 Hz. Amplitude varies greatly but has not been seen to shut off or turn on abruptly and globally as in octopus. Evoked potentials, focally large after flashes of light consist of several waves; the first is largest, positive and peaks at ca. 35 ms (called P35), followed by ca. P75, P95, N110 and smaller waves or oscillations lasting more than 0.5 s. The Upper Following Frequency (highest flashing rate the potentials can follow 1:1), without averaging, is 〉15 flashes/s (20–22 °C); at 20/s the 1∶1 following lasts for 1 or 2 s. The Lower Fusion Frequency of averaged responses is 〈 30/s. Gentle tapping of the tank wall evokes local, brief, fast potentials. No responses have been found to loud air-borne clicks and tone bursts with principal energy at 300 Hz or to electric fields in the bath at 50–100 μV/cm. In a few loci relatively large slow Omitted Stimulus Potentials have been seen following the end of a train of flashes at more than 5/s; these are by definition event related potentials and a special, central form of OFF response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217112
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Acoustic evoked activity in the brain in sharks (1979)
    Springer
    Journal of comparative physiology 129 (1979), S. 223-234 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Averaged evoked potentials (AEP's) were recorded in the medulla, cerebellum, mesencephalon and telencephalon of several species of carcharhinid and triakid sharks, in the anesthetized animal with microelectrodes in the exposed brain and in the unanesthetized animal with implanted electrodes. 2. A preparation is described for recording from implanted electrodes with the unanesthetized shark suspended in the water by rubber bands, subject to air- or water-borne acoustic stimuli, or electric fields or photic stimuli. 3. AEP's were found in each of the levels named above, to acoustic as well as to electric and photic stimuli. The responsive loci are discrete and small. The loci of best response are distinct for each of these three modalities. Anatomical localizations are given to within about one tenth of a neuromere but rarely to the microscopic level. 4. The form, latencies and recovery times of AEP's are given for the several levels and modalities. No interaction occurred between modalities at least with brief stimuli. 5. The best acoustic stimulus for AEP amplitude is a “click” with a resonance of a few hundred Hz. The best tone stimulus is a rapidly rising burst of about 300 Hz. This value may be a function of size of animal, species, and electrode position. The lowest sound pressure threshold observed was −8 dB re 1 μbar near the shark's head (=66 dB SPL), to a click delivered to the water surface. We do not know the velocity-wave amplitude, although it is believed to be the more relevant quantity. 6. Acoustic AEP's were markedly suppressed by background white noise or tones — best at about 100 Hz. 7. When sound was delivered very locally the largest AEP occurred if the sound source was directly over the parietal fossa in the dorsal midline of the head. When sound was delivered at a distance, from a larger speaker, experimental occlusion of the parietal fossa usually suppressed the acoustic AEP. We interpret this to support the view that the fossa is an important portal for sound. 8. In two experiments bilateral section of the VIIIth nerve twig to the macula neglecta, together with some incidental damage to the sacculus greatly reduced the acoustic AEP. This supports the view that the macula neglecta is an important concentration of acoustic receptors but does not definitely confirm that proposal. The evidence argues against any substantial role of the lateral line in these species in response to acoustic stimuli at low amplitudes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657658
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Auditory evoked potentials in the West Indian manatee (Sirenia:Trichechus manatus) (1982)
    Springer
    Journal of comparative physiology 148 (1982), S. 547-554 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Potentials evoked by clicks and tone pips were recorded by fine wires inserted extracranially in four West Indian manatees (Trichechus manatus) in air. Sounds were delivered via padded ear phones. Averaging a few thousand trials at 20/s reveals early peaks at N5.4 (‘vertex’ negativity to a frontal reference, at 5.4 ms), P7.6, N8.8, P9.5 — probably equivalent to waves IV and VII of the typical mammalian auditory brainstem response (ABR). Averaging 100 trials at 〈4/s suffices to reveal a complex sequence of later peaks including N25, P80, N150 and P190; consistent smaller peaks are visible when several hundred trials are averaged. Using tone pips with a rise and fall time of 2–5 ms the carrier frequency becomes important. Evoked potential wave forms are not the same at different frequencies, bringing out the fact that frequency is not a scalar that can be compensated for by intensity. Therefore the method was not used to obtain audiograms; however the largest EPs occur in the range of 1–1.5 kHz. EPs are found up to 35 kHz; almost no evoked potential is discernible at 40 kHz but the undistorted intensity available was limited. This is in reasonable agreement with the theoretical expectation for the upper limit of behavioral hearing from Heffner and Masterton based on head size and aquatic medium. Among several ear phone placements, that over the external auditory meatus was the most effective, but only slightly so. The external canal is presumably fluid or tissue filled and sound enters over a large area. Comparing data for two species on the most effective range of frequencies and the power spectra of their vocalizations,T. manatus is lower thanT. inunguis in both respects. The results show the utility and limitations of the method of recording extracranial evoked potentials to sounds, especially for large and valuable animals under makeshift conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619792
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The jamming avoidance response of high frequency electric fish (1972)
    Springer
    Journal of comparative physiology 77 (1972), S. 23-48 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Using a frequency difference (ΔF) clamp to maintain a stimulus and frustrate the normal escape from a jamming frequency, the response is found to be a characteristic function of the δF between stimulus and fish (Figs. 2, 3, 4, 6). It is graded on both sides of a best ΔF of about 3 Hz (=0.3% inSternarchus, 1.0% inEigenmannia). There is no systematic response whenF stimulus =F fish,regardless of phase. 2. The J. A.R. is graded with intensity (voltage gradient) of the stimulus over a range of more than 100-fold; higher intensities cause some reduction (Fig. 5). The threshold for longitudinal stimulation under certain conditions is lower than 0.25 μV (peak to peak)/cm; for transverse stimulation as in most of the present experiments 0.5 μV (peak to peak)/cm. 3. The best ΔF is the same when added to the fundamental of any harmonic (response detectable at least to the fifth) (Fig. 6). Stimulation around a subharmonic does not elicit the J.A. R. 4. A response to a small ΔF, e.g. 0.2 Hz, can begin within 〈 1/4 cycle of the beat frequency and, without “hunting”, shift in the correct direction. 5. Stimulating with an optimal beat-frequency by amplitude modulation (AM) of a stimulus atF fish, with an AM frequency of 3 Hz, can cause a response though it is confused as to sign. If the stimulus frequency unmodulated is at a ΔF=−20 Hz and therefore almost ineffectual, AM at 17 Hz will cause a response upwards and at 23 Hz downwards (Eigenmannia). These results and the following suggest the fish performs the equivalent of a Fourier analysis and responds to sidebands according to their ΔF. 6. In a 300 HzEigenmannia, if an ineffective stimulus at 280 Hz (ΔF=−20 Hz) is frequency modulated (FM) sinusoidally at 17 Hz between peaks of about 274 and 286 Hz, the fish gives an upwards J.A.R. 7. By curarizingEigenmannia to silence its electric organ we can apply a phase modulated stimulus - a carrier wave whose cycles are systematically phase shifted by a few degrees back and forth at a few Hz. This also causes a response, though only in one direction. 8. If a stimulus is slowly frequency modulated (FM≪ΔF) e.g. between ΔF = + and −6 Hz sinusoidally or triangularly at 10 to 100 sec per cycle, the fish responds and theF fish/ΔF plot traces an hysteresis loop. This is quite well predicted by an analog computer model embodying the best ΔF curve and the time course of response to a ΔF step stimulus (Fig. 7). Unclamped behavior is similar (Figs. 9,10) and predictable from the responses to step stimuli in the clamped condition. 10. A block diagram putting the distinguishable properties into sequence is offered (Fig. 11).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696518
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The jamming avoidance response of high frequency electric fish (1972)
    Springer
    Journal of comparative physiology 77 (1972), S. 1-22 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The J.A.R. is a reflex shift in the frequency of discharge of their electric organs by high frequency electric fish (Gymnotidae:Eigenmannia, Sternarchus) when stimulated by an alternating current in the water, with a frequency close to the fish's. The shift is in the direction of increasing the difference (ΔF) between its frequency (F fish) and that of the stimulus (F stim). The significance of this behavior is presumed to be the maintenance of a private frequency for the object-detection function of the electric system, when another fish of nearly the same frequency approaches. 2. The pathway (Fig. 1) includes a high precision pacemaker unit in the medulla under the tonic influence of electroreceptors. The simplicity of the relevant parameters and the convergence on one command unit in a complete piece of quantifiable social behavior attracts attention to the J.A.R. 3. The latency, time course, form, asymmetry, and variability, the effects of temperature, anesthesia, mechanical and electrical disturbance, light, salinity and spontaneous background changes, and the absence of effect of sound are described (Figs. 2, 3, 4, 5). 4. Eigenmannia will usually shiftF fish up for a — ΔF and down for a +ΔF, rather symmetrically;Sternarchus will only shift upwards and gives no response to a +ΔF. 5. Experimentally isolating parts of the system indicates that the fish does not compare the stimulus frequency with its pacemaker frequency directly but must receive both through the same set of electroreceptors. 6. The stimuli of opposite effect, when given simultaneously cause an intermediate response, i.e. both stimuli are effective. 7. The response survives section of the posterior branch of the anterior lateral line nerves bilaterally and, with slightly raised threshold and latency, of the supraorbital and maxillary branches as well, leaving only the mandibular. It survives partial lesions of the corpus cerebelli and valvula and complete transection in front of the mesencephalon. Lesions of the torus semicircularis of the mesencephalon cause loss or gross abnormality of the J.A.R. 8. The ΔF sensitivity, dynamic range and other properties suggest that the biological significance of preserving a private frequency lies in the need of unknown brain mechanisms, that analyze the fish's own field for object detection, to function over a considerable range of distance from object to fish and therefore of voltage of a signal clearly the fish's own. 9. Evidence from bringing two or more fish together, whose separate frequencies are close, suggests the J.A.R. is used in natural social situations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696517
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Acoustically evoked potentials in midbrain auditory structures in sea lions (Pinnipedia) (1971)
    Springer
    Journal of comparative physiology 74 (1971), S. 372-387 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Twelve sea lions (Zalophus californianus) and one harbor seal (Phoca vitulina) were examined by recording evoked potentials in response to sound from the inferior colliculus and adjacent structures, under barbiturate or after implanting and coming out of anesthesia. Results were similar in air and under water. The averaged response evoked by a sharply rising tone consists of early, brief peaks and later, slow waves (Fig. 1). The latency of the earliest deflection is 3.5 to 4.8 ms from the moment of arrival of a sound pip at the ear. The potential increases in size with sound intensity approximately as a power function, over a dynamic range of 60–70 db (Fig. 2). Masking is qualitatively similar to that in common laboratory species. The properties of the midbrain response are strikingly different from those in porpoises, reported elsewhere. The pinniped is not so specialized for extremely short duration, fast rise time, sounds or for rapid recovery or ultrasonic frequencies (Figs. 3, 4, 7, 8). Evoked potentials fail to show response above 30–35 kHz at 100 db SPL; best frequency is about 4–6 kHz (Figs. 5, 6). Threshold by this method is about 20 db SPL in air. Frequency modulated tones are markedly more effective in some loci but less so than in porpoises under water. The receptive field is essentially total and directionality weak, in contrast with porpoises. Physiological results cannot settle the question whether echolocation is employed but they can indicate lack of high specialization for the types of sounds bats and porpoises use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341402
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A new electroreceptive teleost:Xenomystus nigri (Osteoglossiformes: Notopteridae) (1982)
    Springer
    Journal of comparative physiology 148 (1982), S. 345-352 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The African knife fish,Xenomystus nigri, is found to be sensitive to weak electric fields by the method of averaged evoked potentials from the brain. Slow waves and spikes were recorded in or near the lateral line area of the medulla and the torus semicircularis of the mesencephalon in response to long pulses (best 〉 50 ms) and low frequency sine waves (best ca. 10 Hz) of voltage gradients down to 〈 10 μV/cm. Evoked waves in the lateral line area are a sequence of negative and positive deflections beginning with a first peak at ca. 24 ms; in the torus semicircularis the first peak is at ca. 37 ms. Spikes are most likely in the torus between 50 and 80 ms after ON. At each recording locus there is a best axis of the homogeneous electric field and a better polarity. Effects of stimulus intensity, duration and repetition are described. The physiological properties are similar to those of ampullary receptor systems in mormyriforms, gymnotiforms and siluriforms. Confirming Braford (1982),Xenomystus has a large medullary nucleus resembling the nucleus otherwise peculiar to mormyriforms, gymnotiforms and siluriforms and now called the electrosensory lateral line lobe (ELLL; formerly the posterior lateral line lobe). We describe the projections of anterior and posterior lateral line nerves by HRP applied to the proximal stump of a cut nerve. A descending central ramus of the anterior lateral line nerve and a lateral component of the ascending ramus of the posterior lateral line nerve end in part in the ELLL. Electroreception, including the system of discrete central structures mediating it, is for the first time found to be less than an ordinal or even a family character, but apparently a characteristic of the subfamily Xenomystinae. Species of the other subfamily, Notopterinae as well as of the other families of osteoglossiforms (Osteoglossidae, Hiodontidae and Pantodontidae), lack the ELLL.Notopterus andPantodon are found to lack the evoked potential. The positive finding of evoked activity to feeble electric field is found to be the most practical method for searching widely among fishes for the presence of the electrosense modality and its central pathways. The anatomical criterion of an ELLL can now be taken to be a good criterion for the presence of this sensory system. The absence of evoked response correlates well with the absence of an ELLL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00679019
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...