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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
ACTIVE SENSING

Lecture 7:

Energy-emitting Active Sensing Systems

ELECTRIC FISH

energy emitting active sensing
Energy-emitting active sensing

Geometry

M. E. Nelson ֶ M. A. MacIver J Comp Physiol A (2006) 192: 573–586

slide3

Energy-emitting active sensing

Frequency and duration ranges

M. E. Nelson ֶ M. A. MacIver J Comp Physiol A (2006) 192: 573–586

energy emitting active sensing1
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

daphnia signal characteristics

The prey:

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

Daphnia

1 mm

mechanosensory
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.

bioelectric fields low freq
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.

bioelectric fields low freq1
Bioelectric fields (low freq)

Orientation dependent

W. Wojtenek, L. Wilkens, et al.

bioelectric fields low freq2
Bioelectric fields (low freq)

Movement dependent

W. Wojtenek, L. Wilkens, et al.

daphnia signal characteristics1
Daphnia signal characteristics
  • Mechanosensory stimuli
  • Low-frequency bioelectric fields

Daphnia

1 mm

the duck billed platypus
The duck-billed platypus

uses passive electro and mechano reception to localize prey

slide13

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

daphnia signal characteristics2
Daphnia signal characteristics
  • Mechanosensory stimuli
  • Low-frequency bioelectric fields
  • Perturbations to the fish’s high-frequency electric field

Daphnia

1 mm

electric field generation power considerations
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

self generated electric field
Self-generated Electric Field

isopotential lines (peak, in microvolts)

M. E. Nelson

self generated electric field1
Self-generated Electric Field

current flows perpendicular to the isopotential lines

M. E. Nelson

electroreceptors 15 000 tuberous electroreceptor organs 1 nerve fiber per electroreceptor organ
Electroreceptors ~15,000 tuberous electroreceptor organs1 nerve fiber per electroreceptor organ

Black ghost knifefish

mechano

Fabrizio Gabbiani, Nat Neurosci 2003

prey capture kinematics
Prey capture kinematics

Longitudinal velocity

acceleration

Distance to closest point on body surface

electric field generation electric organ design1
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.
electric field generation electric organ design2
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.
electric field generation proprioception electroreception
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
electric field generation proprioception electroreception1
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

emitted energy active sensing
emitted-energy active sensing

Complications with

  • conspicuousness
    • Detection of energy by prey and predators
  • confusion with peers
emitted energy active sensing1
emitted-energy active sensing

Adaptations specific to

  • conspicuousness
    • Detection of energy by prey and predators
  • confusion with peers
  • technology war
  • ciphering
  • jamming avoidance
technology war
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

technology war1
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.

ciphering
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?

jamming avoidance1
Jamming avoidance

Masashi Kawasaki Current Opinion in Neurobiology 1997, 7:473-479

jamming avoidance2
Jamming avoidance

WALTER METZNER, The Journal of Experimental Biology 202, 1365–1375 (1999)

emitted energy active sensing2
emitted-energy active sensing

Adaptations specific to

  • conspicuousness
    • Detection of energy by prey and predators
  • confusion with peers
  • technology war
  • ciphering
  • jamming avoidance
active sensing1
ACTIVE SENSING

End of lecture 7

Lecture 7:

Energy-emitting Active Sensing Systems

ELECTRIC FISH