Jamming avoidance fish

Question 1

Convergent evolution

Answer 1

Many distant species evolve the same trait, electroreception common in many fish

Question 2

Passive Electroreception vs Active Electrolocation

Answer 2

Use ampullary receptors to passively listen, don’t actively send out signals, just perceive
Some fish have electric organs to actively generate a field, strong/weak for defense/electrolocation

Question 3

Electrocytes

Answer 3

Cells in electric organ, parallel series, each 10mv, combine to get 1V, pacemaker nucleus to make a frequency

Question 4

Two receptor types

Answer 4

Tuberous - tuned to own EOD
Ampullary - common to all fish with Electroreceptors

Question 5

Interference

Answer 5

Sense electric field all over body
signals can mix with neighbor
Constructive = same phase, build in amplitude
Destructive = different phase, cancel out

Question 6

What is the Jamming avoidance response

Answer 6

Fish will change own frequency to maximally differ from a neighbor’s frequency
Will raise own if own is higher than neighbor
Will lower own is own is lower than neighbor
Maximally differ the frequency

Question 7

What is the Df

Answer 7

The sign difference
neighbor - own frequency = Df
If positive, neighbor higher so Lower own
If negative = neighbor lower so Raise own

Question 8

How determine own frequency

Answer 8

NOT with internal pacemaker frequency
Must externally sense frequency with receptors
Block Pacemaker with Achr antagonist, and use artificial field, still react as normal
TUBEROUS ERs DENSE AROUND HEAD
But still compare across WHOLE BODY, to determine own vs mixed signal

Question 9

How ERs percieve signal

Answer 9

Sense signal only is PERPENDICULAR to body
Some points more mixed than others,
Own signal excites all regions equally, neighbor only for perpendicular

Question 10

Beat cycle

Answer 10

Difference in Hz Between two freqs, cycles of constructive and destructive interference
MODULATION IN PHASE AND AMPLITUDE

Question 11

Plotting phase/amplitude,df signs

Answer 11

Sense phase info at Positive Zero crossings of wave amplitude
Counterclockwise = +Df, lower own, Phase lags when amplitude rises, leads when falls
Clockwise = -Df, raise own, lags when falls, leads when rises

Question 12

How sense Df?

Answer 12

Compare mixed signal to pure
SAMPLE amplitude/phase from many body points
TAKE LARGER AMPL. MODULATION for determining where mixed signal is

Question 13

Two problems in JAR

Answer 13

Extracting df Sign, and putting that into motor output to change EOD frequency

Question 14

Two types Tuberous Receptor

Answer 14

T-type = phase locked to pos. zero crossing (time code)
P-type = increase fire to rise in amplitude (probability code)
These two receptors can form the phase/amplitude graph to do JAR!

Question 15

Pathway for JAR

Answer 15

ELL, TORUS, NE, SPPN or PPn, Pacemaker

Question 16

Electrosensory lateral line Lobe ELL

Answer 16

Overrep for head receptors
Parallel process T/P-type

Question 17

T-type in ELL

Answer 17

Converge to Spherical cells
Electrical synapse fast
Coincidence detector, less jitter in spherical

Question 18

P-type in ELL

Answer 18

Pyramidal cells
Basilar pyramidal = E-unit, excite to rise in amp
Nonbasilar pyramidal = I-unit, inhibit to rise in amp, less inhibition when no rise = fire more

Question 19

Torus semicircularis layers

Answer 19

Spherical/pyramidal project to diff layers
Spherical only to layer 6, pyramidal to others

Question 20

Torus cells Time

Answer 20

Giant cells = excitatory from spherical, local phase coding
Spherical to small cells, and giant to small cells too
Small cells excitaotry, converge input
SMALL CELLS respond to DIFFERENCE IN TIMING ACROSS BODY
SMALL CELLS CODE DIFFERENTIAL PHASE, NO AMP RESPONSE, delay/advance units
somatotopic

Question 21

Torus cells Amp

Answer 21

Small cells from layer 6 to other layers
Somatotopic E/I cells from ELL code amplitude in other layers
Layers somatotopic stacked, perpendicular amp and phase
Converge AMP AND PHASE IN OTHER LAYERS (not 6)

Question 22

4 sign-selective cells Torus

Answer 22

E-unit/I-unit combine with Delay/Advance unit small cells
Combine to create E-adv, E-del, I-adv, I-del
Each code for half a circle of Df
E-adv and I-del for -Df
E-del and I-adv for +Df
Ambiguous to sign response, DEPENDS ON ORIENTATION
So torus has basic amp/phase only, and combination sign selective!

Question 23

Nucleus Electrosensorius

Answer 23

INTEGRATES sign-selective for whole circle, UNAMBIGUOUS
Ne up = -Df, clockwise, fish higher raise own, E-adv, I-del
Ne down = +Df, counter, fish lower, lower own, E-del, I-adv

Question 24

Glutamate and Lesion Ne

Answer 24

Lesion ne = no JAR
Glutamate in NE up = EOD up and vice versa
NE uses glutamate to stimulate further regions

Question 25

PPn

Answer 25

Ne up to PPn
Ne uses glutamate to excite PPn
PPn excites Pacemaker with AMPA receptors
Ampa antagonist = no EOD raise

Question 26

SPPn

Answer 26

Ne down to SPPn
Sppn tonically inputs to pacemaker
Ne down uses GABA on Sppn,
When NE down excited, more inhibition on SPPn = less excite to Pacemaker, = EOD goes down
SPPn uses NMDA receptors onto Pacemaker
NMDA antagonist = no EOD down