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L22. Mate Recognition and Courtship in Electric Fish

Oct. 3, 2011

Carl D. Hopkins

BIONB 4240

Announcements

• Writing assignment and discussion Wednesday

• No discussion Wednesday 10/12 after fall break

• Monday 10/17: Wikipedia Workshop

Project outline: 7 main themes or Headings

Preliminary bibliography (complete bibliographic references required for every source used in this project. On Wikipedia, every statement, every bit of evidence is supported by a primary or a secondary reference source. Wikipedia is not the place for original opinions theories, nor is it the place for publishing original data).

REVIEW: Neuronal Implementation of the Jamming Avoidance Response (JAR)

402 Hz Df = -4 Hz

398 Hz Df = +4 Hz

410 Hz

390 Hz

Df = fneighbor - fown

EOD Frequency (Hz)

Together, T-units and P-units provide the

necessary information for executing the JAR

+Df -Df

Neuroanatomy of the JAR

Heiligenberg (1991) In: Neural Nets in Electric Fish

Spherical cells

and pyramidal

cells project to

different laminae

• Pyramidal cells

project to several

laminae in the torus

(3, 5, 7, and 8)

• Spherical cells

project exclusively to

lamina 6

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Neuroanatomy of the JAR sPPn

-Df-selective

E/adv

I/del

nE integrates input from sign-selective neurons

in the torus and drives prepacemaker nuclei

nE

nE

PPn

sPPn

Pn

+Df-selective

E/del

I/adv

The African fish Gymnarchus

also performs the JAR

The electrosensory systems of Gymnarchus

and Eigenmannia evolved independently

Gymnarchus Eigenmannia

electroreception electroreception

EOD EOD

Neuronal implementation of

the JAR in Gymnarchus

Masashi Kawasaki

• Like Eigenmannnia, Gymnarchus does

not have a corollary discharge

• Gymnarchus uses the same algorithm

of combining information about

amplitude and differential phase

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Gymnarchus also has separate amplitude-

and time-coding primary afferents

S-unit

O-unit

Amplitude-sensitive cell in ELL

• Gymnarchus has E-units

and I-units in ELL, just

like Eigenmannia

Phase-sensitive cell in ELL

• Eigenmannnia

calculates differential

phase in the torus

• Gymnarchus

calculates differential

phase in ELL

Sign-selective cells in the torus

• Gymnarchus has sign-

selective neurons in the

torus, just like Eigenmannia

1) It is sometimes advantageous to study novel behaviors

because they are well-suited to neurophysiological study

2) Task-specific functions are encoded in separate, often

parallel, channels. Time and amplitude channels serve

specialized functions (similar to barn owl)

3) Recognition units emerge at higher levels in the sensory

hierarchy. The complex recognition properties arise from

successive analysis of features

4) Recognition units may drive motor output

5) Identical computational algorithms may evolve in unrelated

species by convergent evolution

6) Neuronal substrates for similar functions may involve very

different neuronal subtypes

What have we learned from studying the JAR? MORMYRIFORMES

GYMNOTIFORMES

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Relevant Evolutionary Principles

• Homologous Traits: common traits found in related species

• similarities result from common ancestry

• differences result from divergent evolution (selection

operating in different directions)

• Homoplastic Traits: common traits found in un-related species

• differences reflect different ancestry

• similarities reflect convergent evolution (selection operating in

similar directions)

•These general principles can be used to make inferences

about functional characteristics resulting from selection

• Gymnotiformes and Mormyriformes

• Differences: different evolutionary histories

• Similarities: common selective pressures

Independent evolution of electric receptors and electric organs

electroreception

© Hopkins. In Lavoué et al, in preparation

Electric Organ Discharge (EOD)

Wave-

Type

Pulse-

Type

Apteronotus leptorhynchus

Eigenmannia virescens

Gymnarchus niloticus

Sternopygus macrurus

Brienomyrus niger

Mormyrus rume

Gymnotus carapo

Hypopomus

brevirostris

2 Basic Components to the EOD

Wave-Type

Pulse-Type

EOD Waveform EOD Frequency/Timing

Eigenmanni

a virescens

Brienomyru

s niger

1 ms

1 ms

12 ms

1 s

Direct

Link

EOD Waveform in Mormyroid Fishes

EOD waveform:

1) species-specific

2) sexually dimorphic

3) individual-specific

Variation:

1) number of phases

2) durations

3) relative amplitudes

4) polarity

Electric Organs in Mormyroids

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Electrocytes and EOD Waveform in Mormyriformes a

Hopkins & Bass (1981)

Brienomyrus sp. ‘VAD’

a

Knollenorgan

Knollenorgan

Mormyromast

Ampullary

Communication

active location

passive location

Brienomyrus hopkinsi (Taverne, 1984)

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Friedman & Hopkins (1998)

100 mFriedman & Hopkins (1998)

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100 m

1

2

3

44

5

67

Friedman & Hopkins (1998) Large cell fill: terminals surround small cells.

Big cell, NELL axon

Friedman & Hopkins (1998) Xu-Friedman & Hopkins (1999)