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ACTIVE SENSING

ACTIVE SENSING. Lecture 7: Energy-emitting Active Sensing Systems. ELECTRIC FISH. Energy-emitting active sensing. Geometry. M. E. Nelson ֶ M. A. MacIver J Comp Physiol A (2006) 192: 573–586. Energy-emitting active sensing. Frequency and duration ranges.

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ACTIVE SENSING

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  1. ACTIVE SENSING Lecture 7: Energy-emitting Active Sensing Systems ELECTRIC FISH

  2. Energy-emitting active sensing Geometry M. E. Nelson ֶ M. A. MacIver J Comp Physiol A (2006) 192: 573–586

  3. Energy-emitting active sensing Frequency and duration ranges M. E. Nelson ֶ M. A. MacIver J Comp Physiol A (2006) 192: 573–586

  4. Energy-emitting active sensing detection range Bat (detecting musquitoes) Dolphin (typical prey) Rat (contact range) Electric fish (daphnia) M. E. Nelson ֶ M. A. MacIver J Comp Physiol A (2006) 192: 573–586

  5. Black ghost knifefish (Apteronotus albifrons)

  6. The prey: Daphnia signal characteristics • Mechanosensory stimuli • Low-frequency bioelectric fields • Perturbations to the fish’s high-frequency electric field Daphnia 1 mm

  7. Mechanosensory Jerky propulsion using main antennae • Fast power stroke – Daphnia moves up • Slow recover phase – Daphnia sinks • Normal swimming 1-3 antennal beats s-1 • Escape bursts up to 23 beats s-1 • Typical flows near antennae ~ 10 mm s-1 Kirk, K.L. 1985.

  8. Bioelectric fields (low freq) • Daphnia produce two kinds of bioelectric fields • Orientation dependent: up to 1000 mV, • Movement dependent: 10-100 mV, 3-15 Hz W. Wojtenek, L. Wilkens, et al.

  9. Bioelectric fields (low freq) Orientation dependent W. Wojtenek, L. Wilkens, et al.

  10. Bioelectric fields (low freq) Movement dependent W. Wojtenek, L. Wilkens, et al.

  11. Daphnia signal characteristics • Mechanosensory stimuli • Low-frequency bioelectric fields Daphnia 1 mm

  12. The duck-billed platypus uses passive electro and mechano reception to localize prey

  13. Electro and mechano receptors Distribution ofelectroreceptors (red)and mechanoreceptors (blue) on the dorsum of the platypus bill mechano There are 40,000 electroreceptors and 60,000 mechanoreceptors summed over all srurfaces of the bill

  14. Daphnia signal characteristics • Mechanosensory stimuli • Low-frequency bioelectric fields • Perturbations to the fish’s high-frequency electric field Daphnia 1 mm

  15. Electric Field GenerationPower Considerations • Weakly electric fish devote about 1% of basal metabolic rate to EOD production • Pulse fish • discharge intermittently • higher power per EOD pulse • lower duty cycle • Wave fish • discharge continuously • lower power per EOD cycle • 100% duty cycle M. E. Nelson

  16. Self-generated Electric Field isopotential lines (peak, in microvolts) M. E. Nelson

  17. Self-generated Electric Field current flows perpendicular to the isopotential lines M. E. Nelson

  18. Principles of active electrolocation

  19. Principle of active electrolocation M. E. Nelson

  20. Electroreceptors ~15,000 tuberous electroreceptor organs1 nerve fiber per electroreceptor organ Black ghost knifefish mechano Fabrizio Gabbiani, Nat Neurosci 2003

  21. Prey-capture video analysis

  22. Prey capture behavior

  23. Simulation

  24. Simulation

  25. Prey capture kinematics Longitudinal velocity acceleration Distance to closest point on body surface

  26. Electric Field GenerationElectric Organ Design M. E. Nelson

  27. Electric Field GenerationElectric Organ Design • an electrocyte is a modified muscle cell, that lacks the ability to contract and is specialized for the generation of electric current.

  28. Electric Field GenerationElectric Organ Design • The electric organ contains columns of stacked electrocytes • To generate a signal, the brain sends an electric signal to the first electrocyte in the column, which depolarizes the innervated electroplate surface. This creates a a depolarization wave along the electroplate column. • Essentially, the stacked electroplates act as a series of batteries. The charge generated from these connected "batteries" is released into the surrounding water.

  29. Electric Field GenerationProprioception & electroreception manual touch vibrissal touch electrolocation • body proprioception • sensor’s muscle proprioception • mechanoreception • body proprioception • sensor’s muscle proprioception • mechanoreception • mechano-proprioception • body proprioception • sensor’s muscle proprioception • electrooreception • efference copy

  30. Electric Field GenerationProprioception & electroreception at least two types of electroreceptors: P-type – respond to the intensity of electrical current T-type - respond to the phase of electrical current T-type are analogous to the Whisking cells in rats, but they ARE affected by external modulations

  31. emitted-energy active sensing Complications with • conspicuousness • Detection of energy by prey and predators • confusion with peers

  32. emitted-energy active sensing Adaptations specific to • conspicuousness • Detection of energy by prey and predators • confusion with peers • technology war • ciphering • jamming avoidance

  33. Technology war make the probe less conspicuous to the prey/predator. Example: echolocating killer whales A  dolphins echolocating killer whales B  fish Dolphins can detect the ecolocating signals Fish cannot echolocating killer whales A use irregular short clicks echolocating killer whales B use continuous emission

  34. Technology war make the probe less conspicuous to the prey/predator. Example 2: The prevalence of passive vision systems make it difficult for bioluminescence-based active photoreception to be a viable strategy in most ecological niches. Solution 1: Flaslight fish open and close a “lid” to expose their light organ briefly Solution 2: In deep sea, vision is usually based on the blue-green portion of the spectrum. deep-sea dragonfish have two bioluminescent organs, one of which produces a near infrared wavelength of light that only they can see.

  35. Ciphering keep a private signal that allows decoding the echo Example: CF-FM echolocating bats 1st harmonic is weak and does not reach the peers 2nd harmonic is loud and also echoed well pairing of 2nd harmonic (source) & delayed 2ndharmonic (echo) would include peer calls These bats have evolved cells that respond to 1st harmonic & delayed 2nd harmonic other ciphering tricks?

  36. Jamming avoidance

  37. Jamming avoidance Masashi Kawasaki Current Opinion in Neurobiology 1997, 7:473-479

  38. Jamming avoidance WALTER METZNER, The Journal of Experimental Biology 202, 1365–1375 (1999)

  39. emitted-energy active sensing Adaptations specific to • conspicuousness • Detection of energy by prey and predators • confusion with peers • technology war • ciphering • jamming avoidance

  40. ACTIVE SENSING End of lecture 7 Lecture 7: Energy-emitting Active Sensing Systems ELECTRIC FISH

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