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Journal articles on the topic 'Electrosensor'
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Liu, Jiangtao, Mingying Zhang, Jianbo Liu, and Jianbin Zheng. "Synthesis of Ag@Pt core–shell nanoparticles loaded onto reduced graphene oxide and investigation of its electrosensing properties." Analytical Methods 8, no. 5 (2016): 1084–90. http://dx.doi.org/10.1039/c5ay02672e.
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Nanocomposites of Ag@Pt core–shell nanoparticles loaded on graphene (Ag@Pt–graphene) were synthesized, and further fabricated into an electrosensor to detect hydrogen peroxide (H2O2).
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Papp, G., and F. M. Peeters. "Resistance maps for a submicron Hall electrosensor in the diffusive regime." Journal of Applied Physics 101, no. 11 (June 2007): 113717. http://dx.doi.org/10.1063/1.2745345.
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Qin, Xiaojiao, Shuxia Xu, Li Deng, Rongfu Huang, and Xinfeng Zhang. "Photocatalytic electrosensor for label-free and ultrasensitive detection of BRCA1 gene." Biosensors and Bioelectronics 85 (November 2016): 957–63. http://dx.doi.org/10.1016/j.bios.2016.05.076.
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Neiva, Eduardo G. C., Marcio F. Bergamini, Marcela M. Oliveira, Luiz H. Marcolino, and Aldo J. G. Zarbin. "PVP-capped nickel nanoparticles: Synthesis, characterization and utilization as a glycerol electrosensor." Sensors and Actuators B: Chemical 196 (June 2014): 574–81. http://dx.doi.org/10.1016/j.snb.2014.02.041.
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Kan, Xianwen, Tingting Liu, Hong Zhou, Chen Li, and Bin Fang. "Molecular imprinting polymer electrosensor based on gold nanoparticles for theophylline recognition and determination." Microchimica Acta 171, no. 3-4 (September 19, 2010): 423–29. http://dx.doi.org/10.1007/s00604-010-0455-5.
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Rani, Reetu, Akash Deep, Boris Mizaikoff, and Suman Singh. "Copper Based Organic Framework Modified Electrosensor for Selective and Sensitive Detection of Ciprofloxacin." Electroanalysis 32, no. 11 (October 28, 2020): 2442–51. http://dx.doi.org/10.1002/elan.202060274.
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Guo, Wenjuan, Tingcheng Xia, Huaying Zhang, Minghui Zhao, Luyan Wang, and Meishan Pei. "A Molecularly Imprinting Electrosensor Based on the Novel Nanocomposite for the Detection of Tryptamine." Science of Advanced Materials 10, no. 12 (December 1, 2018): 1805–12. http://dx.doi.org/10.1166/sam.2018.3388.
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HOFMANN, MICHAEL H., MARIANNE FALK, and LON A. WILKENS. "ELECTROSENSORY BRAIN STEM NEURONS COMPUTE THE TIME DERIVATIVE OF ELECTRIC FIELDS IN THE PADDLEFISH." Fluctuation and Noise Letters 04, no. 01 (March 2004): L129—L138. http://dx.doi.org/10.1142/s0219477504001732.
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For many aquatic animals, the electrosense is an important sensory system used to detect prey or conspecifics at short to medium range and for long-range orientation. Passive electroreceptive animals sense the minute electric fields of animate and inanimate sources and it has been thought that they are most sensitive to sources that modulate the field around a few Hertz. Our data on the properties of the electrosensory system in the paddlefish reveal that the firing rate of electrosensory brain stem neurons represents the first derivative of the stimulus, i.e. the rate of change in intensity of an electric field. Furthermore, the responses to several non-periodic stimuli suggest that the electrosensory system monitors changes in field intensity caused by the relative movement between source and receiver and converts spatial field structure into its time derivative form. This new interpretation solves a number of contradictions between behavioural observations and electrophysiological studies on the electrosensory system of vertebrates.
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Sutton, Erin E., Alican Demir, Sarah A. Stamper, Eric S. Fortune, and Noah J. Cowan. "Dynamic modulation of visual and electrosensory gains for locomotor control." Journal of The Royal Society Interface 13, no. 118 (May 2016): 20160057. http://dx.doi.org/10.1098/rsif.2016.0057.
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Animal nervous systems resolve sensory conflict for the control of movement. For example, the glass knifefish, Eigenmannia virescens , relies on visual and electrosensory feedback as it swims to maintain position within a moving refuge. To study how signals from these two parallel sensory streams are used in refuge tracking, we constructed a novel augmented reality apparatus that enables the independent manipulation of visual and electrosensory cues to freely swimming fish ( n = 5). We evaluated the linearity of multisensory integration, the change to the relative perceptual weights given to vision and electrosense in relation to sensory salience, and the effect of the magnitude of sensory conflict on sensorimotor gain. First, we found that tracking behaviour obeys superposition of the sensory inputs, suggesting linear sensorimotor integration. In addition, fish rely more on vision when electrosensory salience is reduced, suggesting that fish dynamically alter sensorimotor gains in a manner consistent with Bayesian integration. However, the magnitude of sensory conflict did not significantly affect sensorimotor gain. These studies lay the theoretical and experimental groundwork for future work investigating multisensory control of locomotion.
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Neven, Liselotte, Hanan Barich, Nick Sleegers, Rocío Cánovas, Gianni Debruyne, and Karolien De Wael. "Development of a combi-electrosensor for the detection of phenol by combining photoelectrochemistry and square wave voltammetry." Analytica Chimica Acta 1206 (May 2022): 339732. http://dx.doi.org/10.1016/j.aca.2022.339732.
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Ji, Lifei, Xian Zhou, Jian Zhang, Xin Zhang, Weidong Kang, and Fengchun Yang. "A simple strategy for carboxylated MWNTs as a metal-free electrosensor for anchoring the RhB CN group." Analytical Methods 11, no. 22 (2019): 2868–74. http://dx.doi.org/10.1039/c9ay00744j.
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Organic dye detection requires high sensitivity, low-cost equipment, simplified procedures, and real-time capabilities; thus, electrochemical methods are gradually emerging in this field instead of chromatography.
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Xie, Donghao, Xue-Qing Feng, Xi-Le Hu, Lin Liu, Zhihong Ye, Jun Cao, Guo-Rong Chen, Xiao-Peng He, and Yi-Tao Long. "Probing Mannose-Binding Proteins That Express on Live Cells and Pathogens with a Diffusion-to-Surface Ratiometric Graphene Electrosensor." ACS Applied Materials & Interfaces 8, no. 38 (September 16, 2016): 25137–41. http://dx.doi.org/10.1021/acsami.6b08566.
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Salminen, Jarno, Mark van Gils, Markku Paloheimo, and Arvi Yli-Hankala. "Comparison of train-of-four ratios measured with Datex-Ohmeda’s M-NMT MechanoSensor™ and M-NMT ElectroSensor™." Journal of Clinical Monitoring and Computing 30, no. 3 (July 8, 2015): 295–300. http://dx.doi.org/10.1007/s10877-015-9717-4.
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Zhou, Xian, Wenjing Cheng, Fudan Zhu, Cunli Wang, Fengchun Yang, Weidong Kang, and Xin Zhang. "An effective strategy for developing the CoMoS nanosheets wrapped by oxidized multi-walled carbon nanotubes as an electrosensor of oryzalin." Journal of Electroanalytical Chemistry 878 (December 2020): 114710. http://dx.doi.org/10.1016/j.jelechem.2020.114710.
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MacIver, M. A., N. M. Sharabash, and M. E. Nelson. "Prey-capture behavior in gymnotid electric fish: motion analysis and effects of water conductivity." Journal of Experimental Biology 204, no. 3 (February 1, 2001): 543–57. http://dx.doi.org/10.1242/jeb.204.3.543.
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Animals can actively influence the content and quality of sensory information they acquire from the environment through the positioning of peripheral sensory surfaces. This study investigated receptor surface positioning during prey-capture behavior in weakly electric gymnotiform fish of the genus Apteronotus. Infrared video techniques and three-dimensional model-based tracking methods were used to provide quantitative information on body position and conformation as black ghost (A. albifrons) and brown ghost (A. leptorhynchus) knifefish hunted for prey (Daphnia magna) in the dark. We found that detection distance depends on the electrical conductivity of the surrounding water. Best performance was observed at low water conductivity (2.8 cm mean detection distance and 2 % miss rate at 35 microS cm(−)(1), A. albifrons) and poorest performance at high conductivity (1.5 cm mean detection distance and 11 % miss rate at 600 microS cm(−)(1), A. albifrons). The observed conductivity-dependence implies that nonvisual prey detection in Apteronotus is likely to be dominated by the electrosense over the range of water conductivities experienced by the animal in its natural environment. This result provides the first evidence for the involvement of electrosensory cues in the prey-capture behavior of gymnotids, but it leaves open the possibility that both the high-frequency (tuberous) and low-frequency (ampullary) electroreceptors may contribute. We describe an electrosensory orienting response to prey, whereby the fish rolls its body following detection to bring the prey above the dorsum. This orienting response and the spatial distribution of prey at the time of detection highlight the importance of the dorsal surface of the trunk for electrosensory signal acquisition. Finally, quantitative analysis of fish motion demonstrates that Apteronotus can adapt its trajectory to account for post-detection motion of the prey, suggesting that it uses a closed-loop adaptive tracking strategy, rather than an open-loop ballistic strike strategy, to intercept the prey.
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Kang, Ning, Lifei Ji, Jun Zhao, Xian Zhou, Xianjun Weng, Hui Li, Xin Zhang, and Fengchun Yang. "Uniform growth of Fe3O4 nanocubes on the single-walled carbon nanotubes as an electrosensor of organic dyes and the study on its catalytic mechanism." Journal of Electroanalytical Chemistry 833 (January 2019): 70–78. http://dx.doi.org/10.1016/j.jelechem.2018.11.012.
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Jung, Sarah N., Andre Longtin, and Leonard Maler. "Weak signal amplification and detection by higher-order sensory neurons." Journal of Neurophysiology 115, no. 4 (April 1, 2016): 2158–75. http://dx.doi.org/10.1152/jn.00811.2015.
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Sensory systems must extract behaviorally relevant information and therefore often exhibit a very high sensitivity. How the nervous system reaches such high sensitivity levels is an outstanding question in neuroscience. Weakly electric fish ( Apteronotus leptorhynchus/ albifrons) are an excellent model system to address this question because detailed background knowledge is available regarding their behavioral performance and its underlying neuronal substrate. Apteronotus use their electrosense to detect prey objects. Therefore, they must be able to detect electrical signals as low as 1 μV while using a sensory integration time of <200 ms. How these very weak signals are extracted and amplified by the nervous system is not yet understood. We studied the responses of cells in the early sensory processing areas, namely, the electroreceptor afferents (EAs) and pyramidal cells (PCs) of the electrosensory lobe (ELL), the first-order electrosensory processing area. In agreement with previous work we found that EAs cannot encode very weak signals with a spike count code. However, PCs can encode prey mimic signals by their firing rate, revealing a huge signal amplification between EAs and PCs and also suggesting differences in their stimulus encoding properties. Using a simple leaky integrate-and-fire (LIF) model we predict that the target neurons of PCs in the midbrain torus semicircularis (TS) are able to detect very weak signals. In particular, TS neurons could do so by assuming biologically plausible convergence rates as well as very simple decoding strategies such as temporal integration, threshold crossing, and combining the inputs of PCs.
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Bell, C. C., K. Grant, and J. Serrier. "Sensory processing and corollary discharge effects in the mormyromast regions of the mormyrid electrosensory lobe. I. Field potentials, cellular activity in associated structures." Journal of Neurophysiology 68, no. 3 (September 1, 1992): 843–58. http://dx.doi.org/10.1152/jn.1992.68.3.843.
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1. This is the first of a series of papers on the electrosensory lobe and closely associated structures in electric fish of the family Mormyridae. The study describes the neuronal responses to sensory stimuli and to corollary discharge signals associated with the motor command that drives the electric organ discharge (EOD). The study is focused on the regions of the electrosensory lobe where primary afferent fibers from mormyromast electroreceptors terminate. 2. This first paper of the series describes the field potentials in the caudal lobe of the cerebellum and in the electrosensory lobe. It also describes the different types of unit activity in the caudal lobe of the cerebellum. Granule cells of the caudal lobe of the cerebellum provide the parallel fibers for most of the molecular layer of the electrosensory lobe. Determination of the input and responses of these cells is therefore an important part of the effort to understand the electrosensory lobe. 3. Corollary discharge field potentials evoked by the EOD motor command are very prominent in the caudal lobe of the cerebellum and in the electrosensory lobe. The potentials indicate that corollary discharge excitation affects first the granule cells of the caudal lobe and then, a few milliseconds later, the deeper cellular layers of the electrosensory lobe. The prominence and complexity of the field potentials indicate that corollary discharge signals have an important and varied role in the processing of electrosensory information by the mormyrid electrosensory lobe. 4. The field potentials evoked by electrosensory stimuli suggest that direct primary afferent excitation is limited to the granule and intermediate layers of the electrosensory lobe, as is indicated also by anatomic studies. 5. Proprioceptive units are the most common type of unit recorded in the granule cell region of the caudal lobe of the cerebellum (eminentia granularis posterior). These units have a regular discharge rate that changes tonically in response to slight bending of the trunk, bending of the tail, or bending of individual fins. Proprioceptive input will have a strong effect on the molecular layer of the electrosensory lobe and will thus modulate the responses of electrosensory lobe cells to electrosensory stimuli. Such proprioceptive input to the electrosensory lobe would allow the expected effects of body position changes to be accounted for in the processing of electrosensory information. 6. Units with stereotyped, short-latency corollary discharge bursts to the EOD motor command were the next most common type of unit in the eminentia granularis posterior. These corollary discharge units were not affected by sensory stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)
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Sawtell, Nathaniel B., Claudia Mohr, and Curtis C. Bell. "Recurrent Feedback in the Mormyrid Electrosensory System: Cells of the Preeminential and Lateral Toral Nuclei." Journal of Neurophysiology 93, no. 4 (April 2005): 2090–103. http://dx.doi.org/10.1152/jn.01055.2004.
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Many sensory regions integrate information ascending from peripheral receptors with descending inputs from other central structures. However, the significance of these descending inputs remains poorly understood. Descending inputs are prominent in the electrosensory system of mormyrid fish and include both recurrent connections from higher to lower stages of electrosensory processing and electric organ corollary discharge (EOCD) signals associated with the motor command that drives the electric organ discharge. The preeminential nucleus (PE) occupies a key position in a feedback loop that returns information from higher stages of electrosensory processing to the initial stage of processing in the electrosensory lobe (ELL). This feedback reflects the integration of ascending electrosensory input from ELL, descending input from the lateral toral nucleus (torus), and EOCD inputs to PE. We used intracellular recording and axonal tracing of stained cells to characterize EOCD and electrosensory responses of several cell types in PE and the torus. PE and toral cells exhibit prominent EOCD responses that are not due to EOCD inputs from ELL. PE cells giving rise to a direct feedback projection to ELL respond to electrosensory stimuli with rapid, precisely timed spikes that will affect ELL neurons early during the same EOD cycle. EOCD and electrosensory responses in toral cells are similar to those observed in PE and may be important in shaping feedback to ELL. These results provide an initial description of electrosensory feedback to ELL as well as information about how ascending, descending, and EOCD inputs are combined at higher stages of electrosensory processing.
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Bastian, Joseph. "Electrosensory Organisms." Physics Today 47, no. 2 (February 1994): 30–37. http://dx.doi.org/10.1063/1.881411.
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Kempster, R. M., C. A. Egeberg, N. S. Hart, and S. P. Collin. "Electrosensory-driven feeding behaviours of the Port Jackson shark (Heterodontus portusjacksoni) and western shovelnose ray (Aptychotrema vincentiana)." Marine and Freshwater Research 67, no. 2 (2016): 187. http://dx.doi.org/10.1071/mf14245.
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Elasmobranch fishes (sharks, skates and rays) possess a highly sensitive electrosensory system that enables them to detect weak electric fields, such as those produced by potential prey organisms. Despite several comparative anatomical studies, the functional significance of interspecific variation in electrosensory system morphology remains poorly understood. In the present study, we directly tested the electrosensitivity of two benthic elasmobranchs that share a similar habitat and feed on similarly sized prey items (Port Jackson sharks, Heterodontus portusjacksoni, and western shovelnose rays, Aptychotrema vincentiana), but differ significantly in their electrosensory system morphology. Aptychotrema vincentiana possesses almost five times the number of electrosensory pores of H. portusjacksoni (~1190 and ~239 respectively), yet both species are able to initiate feeding responses to electric-field gradients below 1 nV cm–1, similar to other elasmobranch species tested. However, A. vincentiana showed a greater ability to resolve the specific location of electrosensory stimuli, because H. portusjacksoni would more often overshoot the target and have to turn around to locate it. These results suggested that differences in abundance and distribution of electrosensory pores have little to no effect on the absolute electrical sensitivity in elasmobranchs, and instead, may reflect species-specific differences in the spatial resolution and directionality of electroreception.
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von der Emde, G., and C. C. Bell. "Nucleus preeminentialis of mormyrid fish, a center for recurrent electrosensory feedback. I. Electrosensory and corollary discharge responses." Journal of Neurophysiology 76, no. 3 (September 1, 1996): 1581–96. http://dx.doi.org/10.1152/jn.1996.76.3.1581.
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1. The nucleus preeminentialis (PE) is a large central structure that projects both directly and indirectly to the electrosensory lobe (ELL) where the primary afferents from electroreceptors terminate. PE receives electrosensory input directly from ELL and also from higher stages of the electrosensory pathway. PE is thus an important part of a central feedback loop that returns electrosensory information from higher stages of the system to the initial stage in ELL. 2. This study describes the field potentials and single-unit activity that are evoked in PE by electrosensory stimuli and by corollary discharge signals associated with the motor command that drives the electric organ to discharge. All recordings were extracellular in this study. 3. Two types of negative-going corollary discharge-evoked field potentials were found in PE: 1) a shallow, long-lasting negative wave with a latency at the peak of approximately 11 ms, and 2) a more sharply falling and larger negative wave with a shorter latency at the peak of approximately 9 ms. The long-latency wave was predominant in the dorsolateral and posterior parts of PE, whereas the short-latency wave was predominant in the medial and rostral regions. Both waves were only found in PE and thus can serve for its identification. 4. Electrosensory stimuli given either locally to a restricted skin region or symmetrically to the entire body evoked characteristic field potentials in both regions of PE. The mean latency between the stimulus and the peak of the response was 6.9 ms in the early negativity region and 12.2 ms in the late negative region. The responses to such stimuli were strongly facilitated by the electric organ corollary discharge. 5. Field potential responses to the electric organ corollary discharge were markedly plastic. Responses to the corollary discharge plus a paired electrosensory stimulus decreased over time and the response to the corollary discharge alone was markedly enhanced after a period of such pairing. 6. Local electrosensory stimulation of the skin showed that the caudal-rostral body axis is mapped from dorsal-medial to ventral-lateral in PE. The same somatotopy was found in the regions of the early and late negatives. The ventral and dorsal body appeared not to be separately mapped in PE. The areas representing the head and chin appendage ("Schnauzenorgan") are especially large in PE, due presumably to the high density of electroreceptors in these areas. 7. Two main types of units were recorded in PE: 1) inhibitory (I) cells with a corollary discharge response that was inhibited by an electrosensory stimulus to the center of their receptive fields; and 2) excitatory (E) cells with an excitatory response to electrosensory stimuli that was facilitated by the corollary discharge. Some of the E cells responded to the corollary discharge alone and some did not. Most cells appeared to be responding to input from mormyromast electroreceptors, but a few cells were driven by ampullary electroreceptors and a few by Knollenorgan electroreceptors. 8. The corollary discharge effects on I cells and E cells were plastic and depended on previous pairing with a sensory stimulus. The corollary discharge facilitation of E cells and inhibition of I cells decreased during pairing with a sensory stimulus, and the corollary discharge-driven excitation of I cells was much larger after pairing than before. 9. The results provide an initial overview of a major component in the control of electrosensory information processing by recurrent feedback from higher stages of the system.
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Hofmann, Michael H., Boris P. Chagnaud, and Lon A. Wilkens. "Edge-Detection Filter Improves Spatial Resolution in the Electrosensory System of the Paddlefish." Journal of Neurophysiology 102, no. 2 (August 2009): 797–804. http://dx.doi.org/10.1152/jn.91215.2008.
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In many fishes, prey capture is guided primarily by vision. In the paddlefish, the electrosense can completely substitute for the visual system to detect tiny daphnia, their primary prey. Electroreceptors are distributed over the entire rostrum, head, and gill covers, and there are no accessory structures like a lens to form an image. To accurately locate planktonic prey in three-dimensional space, the poor spatial resolving power of peripheral receptors has to be improved by another mechanism. We have investigated information processing in the electrosensory system of the paddlefish at hind- and midbrain levels by recording single cells extracellularly. We stimulated with a linear array of electrodes that simulated a moving dipole field. In addition, global electric fields were applied to simulate the temporal component of a moving dipole only. Some stimulation were done with sinusoidal fields. The fire rate of cells in the hindbrain followed the first derivative of the stimulus wave form. In contrast, the response of tectal cells were similar to the third derivative. This improves spatial resolution and receptive fields of tectal units are much smaller than the ones of hind brain units. The principle is similar to a Laplacian of Gaussian filter that is commonly used in digital image processing. However, instead of working in the space domain, the paddlefish edge detection filter works in the time domain, thus eliminating the need for extensive interconnections in an array of topographically organized neurons.
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Comertler, Muhammed Seyda, and Ismail Uyanik. "Salience of multisensory feedback regulates behavioral variability." Bioinspiration & Biomimetics 17, no. 1 (December 17, 2021): 016006. http://dx.doi.org/10.1088/1748-3190/ac392d.
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Abstract Many animal behaviors are robust to dramatic variations in morphophysiological features, both across and within individuals. The control strategies that animals use to achieve such robust behavioral performances are not known. Recent evidence suggests that animals rely on sensory feedback rather than precise tuning of neural controllers for robust control. Here we examine the structure of sensory feedback, including multisensory feedback, for robust control of animal behavior. We re-examined two recent datasets of refuge tracking responses of Eigenmannia virescens, a species of weakly electric fish. Eigenmannia rely on both the visual and electrosensory cues to track the position of a moving refuge. The datasets include experiments that varied the strength of visual and electrosensory signals. Our analyses show that increasing the salience (perceptibility) of visual or electrosensory signals resulted in more robust and precise behavioral responses. Further, we find that robust performance was enhanced by multisensory integration of simultaneous visual and electrosensory cues. These findings suggest that engineers may achieve better system performance by improving the salience of multisensory feedback rather than solely focusing on precisely tuned controllers.
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Ramcharitar, J. U., E. W. Tan, and E. S. Fortune. "Global Electrosensory Oscillations Enhance Directional Responses of Midbrain Neurons in Eigenmannia." Journal of Neurophysiology 96, no. 5 (November 2006): 2319–26. http://dx.doi.org/10.1152/jn.00311.2006.
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Eigenmannia, a genus of weakly electric fish, exhibits a specialized behavior known as the jamming avoidance response (JAR). The JAR results in a categorical difference between Eigenmannia that are in groups of conspecifics and those that are alone. Fish in groups exhibit the JAR behavior and thereby experience ongoing, global synchronous 20- to 50-Hz electrosensory oscillations, whereas solitary fish do not. Although previous work has shown that these ongoing signals do not significantly degrade electrosensory behavior, these oscillations nevertheless elicit short-term synaptic depression in midbrain circuits. Because short-term synaptic depression can have profound effects on the transmission of information through synapses, we examined the differences in intracellularly recorded responses of midbrain neurons in awake, behaving fish to moving electrosensory images under electrosensory conditions that mimic solitary fish and fish in groups. In solitary conditions, moving objects elicited Gaussian or sinusoidal postsynaptic potentials (PSPs) that commonly exhibited preferential responses to a direction of motion. Surprisingly, when the same stimulus was presented in the presence of the global oscillations, directional selectivity was increased in all neurons tested. The magnitudes of the differences in PSP amplitude for preferred and nonpreferred directions were correlated with a measure of short-term synaptic depression in both conditions. The electrosensory consequences of the JAR appear to result in an enhancement of the representation of direction of motion in midbrain neurons. The data also support a role for short-term synaptic depression in the generation and modulation of directional responses.
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Bodznick, D., J. C. Montgomery, and M. Carey. "Adaptive mechanisms in the elasmobranch hindbrain." Journal of Experimental Biology 202, no. 10 (May 15, 1999): 1357–64. http://dx.doi.org/10.1242/jeb.202.10.1357.
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The suppression of self-generated electrosensory noise (reafference) and other predictable signals in the elasmobranch medulla is accomplished in part by an adaptive filter mechanism, which now appears to represent a more universal form of the modifiable efference copy mechanism discovered by Bell. It also exists in the gymnotid electrosensory lateral lobe and mechanosensory lateral line nucleus in other teleosts. In the skate dorsal nucleus, motor corollary discharge, proprioceptive and descending electrosensory signals all contribute in an independent and additive fashion to a cancellation input to the projection neurons that suppresses their response to reafference. The form of the cancellation signal is quite stable and apparently well-preserved between bouts of a particular behavior, but it can also be modified within minutes to match changes in the form of the reafference associated with that behavior. Motor corollary discharge, proprioceptive and electrosensory inputs are each relayed to the dorsal nucleus from granule cells of the vestibulolateral cerebellum. Direct evidence from intracellular studies and direct electrical stimulation of the parallel fiber projection support an adaptive filter model that places a principal site of the filter's plasticity at the synapses between parallel fibers and projection neurons.
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Assad, C., B. Rasnow, and P. K. Stoddard. "Electric organ discharges and electric images during electrolocation." Journal of Experimental Biology 202, no. 10 (May 15, 1999): 1185–93. http://dx.doi.org/10.1242/jeb.202.10.1185.
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Weakly electric fish use active electrolocation - the generation and detection of electric currents - to explore their surroundings. Although electrosensory systems include some of the most extensively understood circuits in the vertebrate central nervous system, relatively little is known quantitatively about how fish electrolocate objects. We believe a prerequisite to understanding electrolocation and its underlying neural substrates is to quantify and visualize the peripheral electrosensory information measured by the electroreceptors. We have therefore focused on reconstructing both the electric organ discharges (EODs) and the electric images resulting from nearby objects and the fish's exploratory behaviors. Here, we review results from a combination of techniques, including field measurements, numerical and semi-analytical simulations, and video imaging of behaviors. EOD maps are presented and interpreted for six gymnotiform species. They reveal diverse electric field patterns that have significant implications for both the electrosensory and electromotor systems. Our simulations generated predictions of the electric images from nearby objects as well as sequences of electric images during exploratory behaviors. These methods are leading to the identification of image features and computational algorithms that could reliably encode electrosensory information and may help guide electrophysiological experiments exploring the neural basis of electrolocation.
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Harvey-Girard, Erik, and Leonard Maler. "Dendritic SK channels convert NMDA-R-dependent LTD to burst timing-dependent plasticity." Journal of Neurophysiology 110, no. 12 (December 15, 2013): 2689–703. http://dx.doi.org/10.1152/jn.00506.2013.
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Feedback and descending projections from higher to lower brain centers play a prominent role in all vertebrate sensory systems. Feedback might be optimized for the specific sensory processing tasks in their target brain centers, but it has been difficult to connect the properties of feedback synapses to sensory tasks. Here, we use the electrosensory system of a gymnotiform fish ( Apteronotus leptorhynchus) to address this problem. Cerebellar feedback to pyramidal cells in the first central electrosensory processing region, the electrosensory lateral line lobe (ELL), is critical for canceling spatially and temporally redundant electrosensory input. The ELL contains four electrosensory maps, and we have previously analyzed the synaptic and network bases of the redundancy reduction mechanism in a map (centrolateral segment; CLS) believed to guide electrolocation behavior. In the CLS, only long-term depression was induced by pairing feedback presynaptic and pyramidal cell postsynaptic bursts. In this paper, we turn to an ELL map (lateral segment; LS) known to encode electrocommunication signals. We find remarkable differences in synaptic plasticity of the morphologically identical cerebellar feedback input to the LS. In the LS, pyramidal cell SK channels permit long-term potentiation (LTP) of feedback synapses when pre- and postsynaptic bursts occur at the same time. We hypothesize that LTP in this map is required for enhancing the encoding of weak electrocommunication signals. We conclude that feedback inputs that appear morphologically identical in sensory maps dedicated to different tasks, nevertheless display different synaptic plasticity rules contributing to differential sensory processing in these maps.
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Bastian, J. "Plasticity in an electrosensory system. II. Postsynaptic events associated with a dynamic sensory filter." Journal of Neurophysiology 76, no. 4 (October 1, 1996): 2497–507. http://dx.doi.org/10.1152/jn.1996.76.4.2497.
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1. This report summarizes studies of the changes in postsynaptic potentials that occur as pyramidal cells within the primary electrosensory processing nucleus learn to reject repetitive patterns of afferent input. The rejection mechanism employs "negative image inputs" that oppose or cancel electroreceptor afferent inputs or patterns of pyramidal hyperpolarization or depolarization caused by intracellular current injection. Feedback pathways carrying descending electrosensory as well as other types of information provide the negative image inputs. This study focuses on the role of a directly descending projection from a second-order electrosensory nucleus the nucleus praeeminentialis (nP), which provides excitatory and inhibitory inputs to the apical dendrites of electrosensory lateral line lobe (ELL) pyramidal cells. 2. Electrical stimulation of the pathway linking the nP to the ELL was used to activate descending inputs to the pyramidal cells. Pyramidal cell activity was typically increased due to stimulation of this pathway. Tetanic stimulation of the descending pathway paired with either electrosensory stimuli that inhibited pyramidal cells, or hyperpolarizing current injection, increased the excitation provided by subsequent stimulation of this pathway. Pairing tetanic stimulation with excitatory electrosensory stimuli or depolarizing current injection had the opposite effect. Subsequent activation of the descending pathway inhibited pyramidal cells. 3. Intracellular recordings showed that the increased firing of pyramidal cells evoked by stimulation of the descending pathway following tetanic stimulation paired with postsynaptic hyperpolarization resulted from larger amplitude and longer-duration excitatory postsynaptic potentials (EPSPs). The shift in the effect of activity in this descending pathway to providing net inhibitory input to the pyramidal cells after paired presynaptic activity and postsynaptic depolarization probably results from the potentiation of inhibitory postsynaptic potentials (IPSPs). The EPSP and IPSPs evoked by activity in this descending pathway can be continuously adjusted in amplitude, thereby counterbalancing patterns of pyramidal cell excitation and inhibition received from the periphery with the result that repetitive patterns of afferent activity are strongly attenuated.
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Nelson, M. E., and M. A. Maciver. "Prey capture in the weakly electric fish Apteronotus albifrons: sensory acquisition strategies and electrosensory consequences." Journal of Experimental Biology 202, no. 10 (May 15, 1999): 1195–203. http://dx.doi.org/10.1242/jeb.202.10.1195.
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Sensory systems are faced with the task of extracting behaviorally relevant information from complex sensory environments. In general, sensory acquisition involves two aspects: the control of peripheral sensory surfaces to improve signal reception and the subsequent neural filtering of incoming sensory signals to extract and enhance signals of interest. The electrosensory system of weakly electric fish provides a good model system for studying both these aspects of sensory acquisition. On the basis of infrared video recordings of black ghost knifefish (Apteronotus albifrons) feeding on small prey (Daphnia magna) in the dark, we reconstruct three-dimensional movement trajectories of the fish and prey. We combine the reconstructed trajectory information with models of peripheral electric image formation and primary electrosensory afferent response dynamics to estimate the spatiotemporal patterns of transdermal potential change and afferent activation that occur during prey-capture behavior. We characterize the behavioral strategies used by the fish, with emphasis on the functional importance of the dorsal edge in prey capture behavior, and we analyze the electrosensory consequences. In particular, we find that the high-pass filter characteristics of P-type afferent response dynamics can serve as a predictive filter for estimating the future position of the prey as the electrosensory image moves across the receptor array.
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Baker, Clare V. H., and Melinda S. Modrell. "Insights into Electroreceptor Development and Evolution from Molecular Comparisons with Hair Cells." Integrative and Comparative Biology 58, no. 2 (June 11, 2018): 329–40. http://dx.doi.org/10.1093/icb/icy037.
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Abstract The vertebrate lateral line system comprises a mechanosensory division, with neuromasts containing hair cells that detect local water movement (“distant touch”); and an electrosensory division, with electrosensory organs that detect the weak, low-frequency electric fields surrounding other animals in water (primarily used for hunting). The entire lateral line system was lost in the amniote lineage with the transition to fully terrestrial life; the electrosensory division was lost independently in several lineages, including the ancestors of frogs and of teleost fishes. (Electroreception with different characteristics subsequently evolved independently within two teleost lineages.) Recent gene expression studies in a non-teleost actinopterygian fish suggest that electroreceptor ribbon synapses employ the same transmission mechanisms as hair cell ribbon synapses, and show that developing electrosensory organs express transcription factors essential for hair cell development, including Atoh1 and Pou4f3. Previous hypotheses for electroreceptor evolution suggest either that electroreceptors and hair cells evolved independently in the vertebrate ancestor from a common ciliated secondary cell, or that electroreceptors evolved from hair cells. The close developmental and putative physiological similarities implied by the gene expression data support the latter hypothesis, i.e., that electroreceptors evolved in the vertebrate ancestor as a “sister cell-type” to lateral line hair cells.
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Hjelmstad, G., G. Parks, and D. Bodznick. "Motor corollary discharge activity and sensory responses related to ventilation in the skate vestibulolateral cerebellum: implications for electrosensory processing." Journal of Experimental Biology 199, no. 3 (March 1, 1996): 673–81. http://dx.doi.org/10.1242/jeb.199.3.673.
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The dorsal granular ridge (DGR) of the elasmobranch vestibulolateral cerebellum is the source of a parallel fiber projection to the electrosensory dorsal nucleus. We report that the DGR in Raja erinacea contains a large percentage of units with activity modulated by the animal's own ventilation. These include propriosensory and electrosensory units, responding to either ventilatory movements or the resulting electroreceptive reafference, and an additional population of units in which activity is phase-locked to the ventilatory motor commands even in animals paralyzed to block all ventilatory movements. A principal function of processing in the dorsal nucleus is the elimination of ventilatory noise in second-order electrosensory neurons. The existence of these ventilatory motor corollary discharge units, along with other DGR units responsive to ventilatory movements, suggests that the parallel fiber projection is involved in the noise cancellation mechanisms.
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Brown, Brandon R. "Modeling an electrosensory landscape." Journal of Experimental Biology 205, no. 7 (April 1, 2002): 999–1007. http://dx.doi.org/10.1242/jeb.205.7.999.
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SUMMARYMost biological sensory systems benefit from multiple sensors. Elasmobranchs (sharks, skates and rays) possess an array of electroreceptive organs that facilitate prey location, mate location and navigation. Here, the perceived electrosensory landscape for an elasmobranch approaching prey is mathematically modeled. The voltages that develop simultaneously in dozens of separate sensing organs are calculated using electrodynamics. These voltages lead directly to firing rate modifications in the primary afferent nerves. The canals connecting the sense organs to an elasmobranch's surface exhibit great variation of location and orientation. Here, the voltages arising in the sense organs are found to depend strongly on the geometrical distribution of the corresponding canals. Two applications for the modeling technique are explored: an analysis of observed elasmobranch prey-capture behavior and an analysis of morphological optimization. For the former, results in specific predator-prey scenarios are compared with behavioral observations, supporting the approach algorithm suggested by A. Kalmijn. For the latter, electrosensory performance is contrasted for two geometrical models of multiple sense organs,a rounded head and a hammer-shaped head.
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Pereira, Ana Carolina, and Angel Ariel Caputi. "Imaging in electrosensory systems." Interdisciplinary Sciences: Computational Life Sciences 2, no. 4 (December 2010): 291–307. http://dx.doi.org/10.1007/s12539-010-0049-2.
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Heiligenberg, Walter. "Electrosensory systems in fish." Synapse 6, no. 2 (1990): 196–206. http://dx.doi.org/10.1002/syn.890060212.
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Mohr, Claudia, Patrick D. Roberts, and Curtis C. Bell. "The Mormyromast Region of the Mormyrid Electrosensory Lobe. I. Responses to Corollary Discharge and Electrosensory Stimuli." Journal of Neurophysiology 90, no. 2 (August 2003): 1193–210. http://dx.doi.org/10.1152/jn.00211.2003.
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This is the first of two papers on the electrosensory lobe (ELL) of mormyrid electric fish. The ELL is the first stage in the central processing of electrosensory information from electroreceptors. Cells of the mormyrid ELL are affected at the time of the electric organ discharge (EOD) by two different inputs, EOD-evoked reafferent input from electroreceptors and corollary discharge input associated with the motor command that elicits the EOD. This first paper examines the intracellular responses of ELL cells to these two different inputs in the region of ELL that receives primary afferent fibers from mormyromast electroreceptors. Mormyromast electroreceptors are responsible for active electrolocation. The paper extends previous studies of the mormyrid ELL by describing the physiological responses of cell types, which had been previously identified only morphologically, including: the two types of Purkinje-like medium ganglionic cells, MG1 and MG2; the thick smooth dendrite cells; and the medium fusiform cells. In addition, two previously unrecognized cell types, the large thick smooth dendrite cell and the interzonal cell, are described both morphologically and physiologically for the first time. Finally, new information is provided on the two types of ELL efferent cells, the large ganglionic and large fusiform cells. All cell types, except for the medium fusiform cell, show nonlinear interactions between electrosensory and corollary discharge inputs. All cell types, except for the medium fusiform cell and the interzonal cell, also show plasticity of the corollary discharge response after pairing with electrosensory stimuli.
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Bastian, J. "Plasticity in an electrosensory system. I. General features of a dynamic sensory filter." Journal of Neurophysiology 76, no. 4 (October 1, 1996): 2483–96. http://dx.doi.org/10.1152/jn.1996.76.4.2483.
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1. In this study we describe changes in neuronal responses within the primary electrosensory processing nucleus of a weakly electric fish that occur when the fish are exposed to repetitive patterns of electrosensory stimuli. Extracellular single-unit recordings show that pyramidal cells within the electrosensory lateral line lobe develop, over a time course of several minutes, an insensitivity to repetitive stimuli applied to a cell's receptive field (local stimulus). The pyramidal cell response cancellation only develops if the local stimulus is applied simultaneously with a diffuse pattern of electrosensory stimulation that affects the entire fish, or with proprioceptive stimuli. 2. The mechanism by which responses to repetitive afferent inputs are canceled relies on the central generation of "negative image inputs" that provide increased inhibitory input to a cell's apical dendrites at times when excitatory afferent input is increased. The negative image input becomes excitatory when afferent excitation is reduced or when input from inhibitory interneurons is predominant. The integration of a specific pattern of receptor afferent input with the complementary negative image input results in strong attenuation of pyramidal cell responses. The negative image inputs are plastic, so that a single pyramidal cell can learn to reject a variety of afferent input patterns. 3. These electric fish commonly experience repetitive electrosensory signals as a result of changes in posture. Because the electric organ is located in the trunk and tail, cyclical movements associated with exploratory behaviors result in amplitude modulations (AMs) of the electric field, and these AMs alter electroreceptor afferent firing frequency but not the firing frequency of second-order pyramidal cells. The adaptive cancellation mechanism described in this study can account for the insensitivity of pyramidal cells to reafferent electrosensory stimulation caused by tail movements and other postural changes. 4. The tail movements generate proprioceptive as well as electrosensory inputs, and either of these signals alone provides sufficient information for the generation of negative image inputs. The size of the negative image is larger, however, if both inputs are active. 5. The synaptic plasticity underlying the development of negative image inputs has a long-term component; under appropriate conditions changes in synaptic efficacy persist for > 30 min. 6. Normally functioning glutamatergic synapses are necessary for the expression of the synaptic plasticity associated with this cancellation mechanism. The development of negative image responses is blocked by micropressure ejection of the glutamate antagonist 6,7-dinitroquinoxaline-2,3-dione into the neighborhood of the pyramidal cell apical dendrites. 7. The adaptive cancellation of repetitive inputs is based on anti-Hebbian mechanisms; that is, correlated pre- and postsynaptic activity lead to a reduction in the excitatory input provided by the plastic synapses. As has been shown for several other systems, the cancellation mechanism reduces the cells responses to reafferent patterns of sensory input. In addition, the results of this study indicate that the mechanism may be more general, enabling the system to also cancel patterns of input resulting from exogenous stimuli.
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Meek, J., K. Grant, and C. Bell. "Structural organization of the mormyrid electrosensory lateral line lobe." Journal of Experimental Biology 202, no. 10 (May 15, 1999): 1291–300. http://dx.doi.org/10.1242/jeb.202.10.1291.
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The electrosensory lateral line lobe (ELL) of mormyrid teleosts is the first central stage in electrosensory input processing. It is a well-developed structure with six main layers, located in the roof of the rhombencephalon. Its main layers are, from superficial to deep, the molecular, ganglionic, plexiform, granular, intermediate and deep fiber layers. An important input arises from electroreceptors, but corollary electromotor command signals and proprioceptive, mechanosensory lateral line and descending electrosensory feedback inputs reach the ELL as well. The ELL input is processed by at least 14 cell types, which frequently show plastic responses to different inputs. The large ganglionic and large fusiform cells are the ELL projection cells. They are glutamatergic and project to the isthmic preeminential nucleus and the midbrain lateral toral nucleus. Interneurons are located in all ELL layers and are mostly GABAergic. The most remarkable interneurons are large multipolar cells in the intermediate layer, which have myelinated dendrites making presynaptic terminals contacting granular cells. With respect to the synaptic organization and microcircuitry of the ELL, a number of qualitative and quantitative aspects have been elucidated using electron microscopical and intracellular labeling techniques. However, the pathways by which primary afferent input influences the ELL projection cells are still undetermined: primary afferents do not seem to contact large fusiform or large ganglionic cells directly, but seem to terminate exclusively on granular cells, the axonal properties of which are not known. Consequently, more information of the structural organization of the ELL is still necessary for a detailed understanding of the neural basis of the plastic electrosensory input processing in mormyrids.
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Bell, C. C., and K. Grant. "Sensory processing and corollary discharge effects in mormyromast regions of mormyrid electrosensory lobe. II. Cell types and corollary discharge plasticity." Journal of Neurophysiology 68, no. 3 (September 1, 1992): 859–75. http://dx.doi.org/10.1152/jn.1992.68.3.859.
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1. This is the second of a series of papers on the electrosensory lobe and closely associated structures in electric fish of the family Mormyridae. The focus of the study is on the regions of the electrosensory lobe where primary afferent fibers from mormyromast electroreceptors terminate. 2. This second paper examines the responses of single cells in the mormyromast regions of the electrosensory lobe to electrosensory stimuli and to corollary discharge signals associated with the motor command that drives the electric organ to discharge. All recordings were extracellular. 3. Two major types of cells were identified: I cells, which were inhibited by electrosensory stimuli in the center of their receptive fields; and E cells, which were excited by such stimuli. 4. I cells and E cells shared a number of common features. Both types could have small receptive fields limited to only a few electroreceptors (3–5), and both types were markedly affected by the corollary discharge of the electric organ discharge (EOD) motor command. Cells of both types also showed clear plasticity in their responses to the corollary discharge or to the corollary discharge plus a stimulus. 5. I cells could be subdivided into three subtypes, I1, I2, and I3, on the basis of corollary discharge responses in the absence of sensory stimuli. I1 and I2 cells showed consistent corollary discharge bursts with little or no additional activity beyond the duration of the burst. The corollary discharge bursts of I1 cells were more stereotyped and of shorter latency than those of I2 cells. I3 cells had more spontaneous activity than I1 or I2 cells and minimal cells had more spontaneous activity than I1 or I2 cells and minimal corollary discharge responses in the absence of sensory stimuli. Field potentials indicated that all three subtypes of I cells were recorded in or near the ganglion layer of the electrosensory lobe. 6. Corollary discharge responses were plastic and depended on recent pairing of a sensory stimulus with the EOD motor command. Such plasticity was clearer in I2 and I3 cells than in I1 cells. Inhibitory sensory stimuli were paired with the EOD motor command for periods of a few seconds to several minutes. Such pairing resulted in a marked enhancement of the corollary discharge response in I2 cells, as shown by examining the effect of the motor command after turning off the stimulus. In I3 cells, such pairing resulted in a clear corollary burst to the command at the time of the previously paired inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)
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Chacron, Maurice J., and Joseph Bastian. "Population Coding by Electrosensory Neurons." Journal of Neurophysiology 99, no. 4 (April 2008): 1825–35. http://dx.doi.org/10.1152/jn.01266.2007.
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Sensory stimuli typically activate many receptors at once and therefore should lead to increases in correlated activity among central neurons. Such correlated activity could be a critical feature in the encoding and decoding of information in central circuits. Here we characterize correlated activity in response to two biologically relevant classes of sensory stimuli in the primary electrosensory nuclei, the electrosensory lateral line lobe, of the weakly electric fish Apteronotus leptorhynchus. Our results show that these neurons can display significant correlations in their baseline activities that depend on the amount of receptive field overlap. A detailed analysis of spike trains revealed that correlated activity resulted predominantly from a tendency to fire synchronous or anti-synchronous bursts of spikes. We also explored how different stimulation protocols affected correlated activity: while prey-like stimuli increased correlated activity, conspecific-like stimuli decreased correlated activity. We also computed the correlations between the variabilities of each neuron to repeated presentations of the same stimulus (noise correlations) and found lower amounts of noise correlation for communication stimuli. Therefore the decrease in correlated activity seen with communication stimuli is caused at least in part by reduced noise correlations. This differential modulation in correlated activity occurred because of changes in burst firing at the individual neuron level. Our results show that different categories of behaviorally relevant input will differentially affect correlated activity. In particular, we show that the number of correlated bursts within a given time window could be used by postsynaptic neurons to distinguish between both stimulus categories.
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Fortune, Eric S. "The decoding of electrosensory systems." Current Opinion in Neurobiology 16, no. 4 (August 2006): 474–80. http://dx.doi.org/10.1016/j.conb.2006.06.006.
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Roth, A. "Development of the electrosensory system." Naturwissenschaften 81, no. 6 (June 1994): 269–72. http://dx.doi.org/10.1007/bf01131580.
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Montgomery, J. C., and D. Bodznick. "HINDBRAIN CIRCUITRY MEDIATING COMMON MODE SUPPRESSION OF VENTILATORY REAFFERENCE IN THE ELECTROSENSORY SYSTEM OF THE LITTLE SKATE RAJA ERINACEA." Journal of Experimental Biology 183, no. 1 (October 1, 1993): 203–16. http://dx.doi.org/10.1242/jeb.183.1.203.
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Elasmobranch fish have an electrosensory system which they use for prey detection and for orientation. Sensory inputs to this system are corrupted by a form of reafference generated by the animal's own ventilation, but this noise is reduced by sensory processing within the medullary nucleus of the electrosensory system. This noise cancellation is achieved, at least in part, by a common mode rejection mechanism. In this study we have examined characteristics of neurones within the medullary nucleus in an attempt to understand the neural circuitry responsible for common mode suppression. Our results are in accord with previous indications that ascending efferent neurones of the medullary nucleus are monosynaptically activated from the ipsilateral electrosensory nerves and project to the midbrain. We demonstrate that in Raja erinacea, as has been previously shown in one other species (Cephaloscyllium isabella), ascending efferent neurones typically have a discrete focal excitatory receptive field and an inhibitory receptive field which may be discrete or diffuse and which often includes a contralateral component. We identify a group of interneurones within the medullary nucleus which are driven monosynaptically from the electrosensory nerves, have simple discrete excitatory receptive fields and respond vigorously to imposed common mode signals. The simplest model of the circuitry underlying common mode rejection that is consistent with the evidence is that direct afferent input impinges onto the basal dendrites of the ascending efferent neurones and onto interneurones within the nucleus, and the interneurones in turn inhibit the ascending efferents. The pattern of this projection, including commissural inputs, determines the nature and extent of ascending efferents' inhibitory surrounds and mediates the suppression of common mode signals.
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Turner, R. W., and L. Maler. "Oscillatory and burst discharge in the apteronotid electrosensory lateral line lobe." Journal of Experimental Biology 202, no. 10 (May 15, 1999): 1255–65. http://dx.doi.org/10.1242/jeb.202.10.1255.
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Oscillatory and burst discharge is recognized as a key element of signal processing from the level of receptor to cortical output cells in most sensory systems. The relevance of this activity for electrosensory processing has become increasingly apparent for cells in the electrosensory lateral line lobe (ELL) of gymnotiform weakly electric fish. Burst discharge by ELL pyramidal cells can be recorded in vivo and has been directly associated with feature extraction of electrosensory input. In vivo recordings have also shown that pyramidal cells are differentially tuned to the frequency of amplitude modulations across three ELL topographic maps of electroreceptor distribution. Pyramidal cell recordings in vitro reveal two forms of oscillatory discharge with properties consistent with pyramidal cell frequency tuning in vivo. One is a slow oscillation of spike discharge arising from local circuit interactions that exhibits marked changes in several properties across the sensory maps. The second is a fast, intrinsic form of burst discharge that incorporates a newly recognized interaction between somatic and dendritic membranes. These findings suggest that a differential regulation of oscillatory discharge properties across sensory maps may underlie frequency tuning in the ELL and influence feature extraction in vivo.
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Oswald, Anne-Marie M., Brent Doiron, and Leonard Maler. "Interval Coding. I. Burst Interspike Intervals as Indicators of Stimulus Intensity." Journal of Neurophysiology 97, no. 4 (April 2007): 2731–43. http://dx.doi.org/10.1152/jn.00987.2006.
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Short interspike intervals such as those that occur during burst firing are hypothesized to be distinct features of the neural code. Although a number of correlations between the occurrence of burst events and aspects of the stimulus have been identified, the relationship between burst characteristics and information transfer is uncertain. Pyramidal cells in the electrosensory lobe of the weakly electric fish, Apteronotus leptorhynchus, respond to dynamic broadband electrosensory stimuli with bursts and isolated spikes. In the present study, we mimic synaptic input during sensory stimulation by direct stimulation of electrosensory pyramidal cells with broadband current in vitro. The pyramidal cells respond to this stimulus with burst interspike intervals (ISIs) that are reliably and precisely correlated with the intensity of stimulus upstrokes. We found burst ISIs must differ by a minimum of 2 ms to discriminate, with low error, differences in stimulus intensity. Based on these results, we define and quantify a candidate interval code for the processing of sensory input. Finally, we demonstrate that interval coding is restricted to short ISIs such as those generated in burst events and that the proposed interval code is distinct from rate and timing codes.
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Bastian, J. "Plasticity of feedback inputs in the apteronotid electrosensory system." Journal of Experimental Biology 202, no. 10 (May 15, 1999): 1327–37. http://dx.doi.org/10.1242/jeb.202.10.1327.
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Weakly electric fish generate an electric field surrounding their body by means of an electric organ typically located within the trunk and tail. Electroreceptors scattered over the surface of the body encode the amplitude and timing of the electric organ discharge (EOD), and central components of the electrosensory system analyze the information provided by the electroreceptor afferents. The electrosensory system is used for electrolocation, for the detection and analysis of objects near the fish which distort the EOD and for electrocommunication. Since the electric organ is typically located in the tail, any movement of this structure relative to the rest of the body alters the EOD field, resulting in large changes in receptor afferent activity. The amplitude of these reafferent stimuli can exceed the amplitudes of near-threshold electrolocation signals by several orders of magnitude. This review summarizes recent studies of the South American weakly electric fish Apteronotus leptorhynchus aimed at determining how the animals differentiate self-generated or reafferent electrosensory stimuli from those that are more behaviorally relevant. Cells within the earliest stages of central electrosensory processing utilize an adaptive filtering technique which allows the system preferentially to attenuate reafferent as well as other predictable patterns of sensory input without degrading responses to more novel stimuli. Synaptic plasticity within the system underlies the adaptive component of the filter and enables the system to learn to reject new stimulus patterns if these become predictable. A Ca2+-mediated form of postsynaptic depression contributes to this synaptic plasticity. The filter mechanism seen in A. leptorhynchus is surprisingly similar to adaptive filters described previously in mormyrid weakly electric fish and in elasmobranchs, suggesting that this mechanism may be a common feature of sensory processing systems.
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Molteno, T. C. A., and W. L. Kennedy. "Navigation by Induction-Based Magnetoreception in Elasmobranch Fishes." Journal of Biophysics 2009 (October 18, 2009): 1–6. http://dx.doi.org/10.1155/2009/380976.
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A quantitative frequency-domain model of induction-based magnetoreception is presented for elasmobranch fishes. We show that orientation with respect to the geomagnetic field can be determined by synchronous detection of electrosensory signals at harmonics of the vestibular frequency. The sensitivity required for this compass-sense mechanism is shown to be less than that known from behavioral experiments. Recent attached-magnet experiments have called into doubt the induction-based mechanism for magnetoreception. We show that the use of attached magnets would interfere with an induction-based mechanism unless relative movement between the electrosensory system and the attached magnet is less than 100 m. This suggests that further experiments may be required to eliminate induction as a basis for magnetoreception.
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Roberts, Patrick D. "Modeling Inhibitory Plasticity in the Electrosensory System of Mormyrid Electric Fish." Journal of Neurophysiology 84, no. 4 (October 1, 2000): 2035–47. http://dx.doi.org/10.1152/jn.2000.84.4.2035.
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Mathematical analyses and computer simulations are used to study the adaptation induced by plasticity at inhibitory synapses in a cerebellum-like structure, the electrosensory lateral line lobe (ELL) of mormyrid electric fish. Single-cell model results are compared with results obtained at the system level in vivo. The model of system level adaptation uses detailed temporal learning rules of plasticity at excitatory and inhibitory synapses onto Purkinje-like neurons. Synaptic plasticity in this system depends on the time difference between pre- and postsynaptic spikes. Adaptation is measured by the ability of the system to cancel a reafferent electrosensory signal by generating a negative image of the predicted signal. The effects of plasticity are tested for the relative temporal correlation between the inhibitory input and the sensory input, the gain of the sensory signal, and the presence of shunting inhibition. The model suggests that the presence of plasticity at inhibitory synapses improves the function of the system if the inhibitory inputs are temporally correlated with a predictable electrosensory signal. The functional improvements include an increased range of adaptability and a higher rate of system level adaptation. However, the presence of shunting inhibition has little effect on the dynamics of the model. The model quantifies the rate of system level adaptation and the accuracy of the negative image. We find that adaptation proceeds at a rate comparable to results obtained from experiments in vivo if the inhibitory input is correlated with electrosensory input. The mathematical analysis and computer simulations support the hypothesis that inhibitory synapses in the molecular layer of the ELL change their efficacy in response to the timing of pre- and postsynaptic spikes. Predictions include the rate of adaptation to sensory stimuli, the range of stimulus amplitudes for which adaptation is possible, the stability of stored negative images, and the timing relations of a temporal learning rule governing the inhibitory synapses. These results may be generalized to other adaptive systems in which plasticity at inhibitory synapses obeys similar learning rules.
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New, John G. "The Evolution of Vertebrate Electrosensory Systems." Brain, Behavior and Evolution 50, no. 4 (1997): 244–52. http://dx.doi.org/10.1159/000113338.
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Freitas, Renata, GuangJun Zhang, James S. Albert, David H. Evans, and Martin J. Cohn. "Developmental origin of shark electrosensory organs." Evolution Development 8, no. 1 (January 2006): 74–80. http://dx.doi.org/10.1111/j.1525-142x.2006.05076.x.
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