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Vector 2 (6.3)

(LDCMD?)

0

200

400

Vector 9 (5.3) Vector 13 (4.8)

Time to collision (s)

-3 -2 -1 0 1

Vector 10 (5.0) Vector 6 (5.5)

Time to collision (s)

-3 -2 -1 0 1

Vector 15 (4.6)

Vector 8 (5.5)

0

200

400

Vector 21 (1.8)

Time to collision (s)

-3 -2 -1 0 1

Vector 11 (4.9)

0

200

400

Vector 1 (6.8)

(DCMD?)

0

200

400

Vector 3 (6.0) Vector 4 (6.0)Vector 7 (5.5) Vector 5 (5.7)

Vector 16 (4.4)

Time to collision (s)

-3 -2 -1 0 1

Vector 14 (4.8)

Fir

ing r

ate

(sp

ikes

/s)

0

200

400

Vector 19 (3.2)

Time to collision (s)

-3 -2 -1 0 1

0

400

800

1200

Vector 20 (2.6)

Time to collision (s)

-3 -2 -1 0 1

0

200

400

Vector 12 (4.9)

Vector 17 (3.9)

Vector 18 (3.7)

Mean of all units (n = 162)

Time to collision (s)

-3 -2 -1 0 1

Fir

ing r

ate

(sp

ikes

/s)

0

20

40

60

80

100

Locust visual motion detection involves the

Descending Contralateral Movement Detector

(DCMD) and Late DCMD (LDCMD - inset)1, each

of which responds to approaching objects. The

DCMD has been implicated in mediating collision

avoidance behaviour2-4 and firing rate modulation

also reflects trajectory changes associated with

compound object motion5. We used multi-channel

recordings from the ventral nerve cord, spike

sorting and principal component analysis to

determine if putative neural populations respond

to simple looms and/or complex object motion.

INTRODUCTION

Locusts (n=20) placed in the set-up (A) were

presented with simple and complex object motion

trajectories (7 cm disc at 3 m/s, B) during

multichannel recording from the ventral nerve

cord (C).

METHODS

Responses of discriminated units from each locust presented with a 90° loom. Data plotted as a cumulative

sum within a 99% confidence interval ellipse (top) and peristimulus time histogram (bottom) of Gaussian-

smoothed (50 ms bin) firing rate aligned to time of projected collision (red vertical line).

RESULTS

Principle component analysis reveals unique response types

A) Scree plot from PCA (50 ms bins)

on units responding to looming (non-

shaded above). 21 components with

eigenvalues >1 (red line) accounted

for 63% of the variation in the data.

B) Population vectors (with

eigenvalues) of 21 components

responding to looming from 90° were

divided into 5 general response types

based on time of collision (TOC)-

associated firing rate modulation.

Inset - average response to looming

from 162 units.

Firing rates of vectors with largest eigenvalues

from each Type (plus vector 2 from Type 1) were

aligned (red line) with time at 90° azimuth (T90,

translating) or TOC (compound). Blue line

indicates time of transition (TOT). Bottom plots

represent mean firing rate of all units (n = 162).

Acknowledgements

Funding provided by the Natural Science and Engineering Research Council

of Canada, the Canada Foundation for Innovation and the University of

Saskatchewan

References 1Gray et al. (2010) J. Comp. Physiol. A. 196:927-38. 2Santer et al. (2006) J.

Neurophysiol. 95:3391-3400. 3Santer et al. (2007) J. Comp. Physiol. A. 194:69-

77. 4Fotowat & Gabbiani (2007) J. Neurosci. 27:10047-59. 5McMillan & Gray

(2012) J. Neurophysiol. 108:1052-68.

SUMMARY

Unit looming response statistics (mean ± S.D./locust)

Total units Response No response

# 240 (12 ± 2.8) 162 (8 ± 2.1) 78 (4 ± 2.4)

% 67.5 (69) 32.5 (31)

ACKNOWLEDGEMENTS &

REFERENCES

Locust 1 Locust 20

0 20 L01_AD00a

0 40 L01_AD00b

0 20 L01_AD00c

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0 100 L01_AD00f

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0 20 L01_AD04a

0 20 L01_AD04b

0 20 L01_AD04c

0 40 L01_AD04d

0 L01_AD04e

0 L01_AD04f

0 40 L01_AD04g

0 L01_AD04h

0 L01_AD04i

0 80 L01_AD04j

-3 -2 -1 0 1 0 200

L01_AD04k

Fir

ing r

ate

(sp

ikes

/s)

0

0 40 L04_AD00a

0 100 L04_AD00b

0 100 L04_AD00c

100 L04_AD00d

0 L04_AD00e

0 80 L04_AD04a

0 L04_AD04b

0 100 L04_AD04c

0 40 L04_AD04d

0 L04_AD04e

0 L04_AD04f

-3 -2 -1 0 1 0 L04_AD04g

0 20 L06_AD00a

0 L06_AD00b

0 20 L06_AD00c

0 L06_AD00d

0 L06_AD00e

0 L06_AD00f

0 400 L06_AD00g

0 L06_AD04a

0 L06_AD04b

0 100 L06_AD04c

0 40 L06_AD04d

0 100 L06_AD04e

-3 -2 -1 0 1 0 20

L06_AD04f

0 20 L02_AD00a

0 L02_AD00b

0 L02_AD00c

0 100 L02_AD00d

0 40 L02_AD00e

0 L02_AD00f

0 100 L02_AD00g

0 100 L02_AD00h

0 100 L02_AD00i

0 20 L02_AD04a

0 20 L02_AD04b

0 L02_AD04c

-3 -2 -1 0 1 0 80

L02_AD04d

0 40 L03_AD00a

0 20 L03_AD00b

0 20 L03_AD00c

0 200 L03_AD00d

0 L03_AD00e

0 20 L03_AD00f

0 40 L03_AD00g

0 L03_AD00h

0 200 L03_AD00i

0 100 L03_AD04a

0 L03_AD04b

0 200 L03_AD04c

-3 -2 -1 0 1 0 L03_AD04d

0 20 L05_AD00a

0 L05_AD00b

0 200 L05_AD00c

0 L05_AD04a

0 L05_AD04b

0 100 L05_AD04c

0 20 L05_AD04d

0 100 L05_AD04e

-3 -2 -1 0 1 0 100 L05_AD04f

0 20 L07_AD00a

0 200 L07_AD00b

0 L07_AD00c

0 80 L07_AD00d

0 20 L07_AD00e

0 L07_AD00f

0 100 L07_AD00g

0 20 L07_AD04a

0 20 L07_AD04b

0 100 L07_AD04c

0 20 L07_AD04d

0 L07_AD04e

0 80 L07_AD04f

0 100 L07_AD04g

-3 -2 -1 0 1 0 100

L07_AD04h

0 80 L08_AD00a

0 100 L08_AD00b

0 100 L08_AD00c

0 20 L08_AD00d

0 200 L08_AD00e

0 20 L08_AD04a

0 40 L08_AD04b

0 L08_AD04c

0 200 L08_AD04d

-3 -2 -1 0 1 0 200 L08_AD04e

0 20 L09_AD00a

0 L09_AD00b

0 40 L09_AD00c

0 200 L09_AD00d

0 20 L09_AD04a

0 20 L09_AD04b

0 L09_AD04c

0 80 L09_AD04d

-3 -2 -1 0 1 0 100 L09_AD04e

0 L10_AD00a

0 100 L10_AD00b

0 100 L10_AD00c

0 200 L10_AD00d

0 40 L10_AD04a

0 100 L10_AD04b

0 100 L10_AD04c

0 L10_AD04d

0 100 L10_AD04e

0 80 L10_AD04f

-3 -2 -1 0 1 0 L10_AD04g

0 200 L11_AD00a

0 100 L11_AD00b

0 200 L11_AD00c

0 200 L11_AD00d

0 40 L11_AD04a

0 200 L11_AD04b

0 200 L11_AD04c

-3 -2 -1 0 1 0 200 L11_AD04d

0 L12_AD00a

0 100 L12_AD00b

0 L12_AD00c

0 200 L12_AD00d

0 100 L12_AD00e

0 L12_AD04a

0 L12_AD04b

0 200 L12_AD04c

-3 -2 -1 0 1 0 100 L12_AD04d

0 100 L13_AD00e

0 200 L13_AD00f

0 20 L13_AD04a

0 40 L13_AD04b

0 L13_AD04c

0 40 L13_AD04d

0 40 L13_AD04e

0 20 L13_AD04f

0 100 L13_AD04g

0 L13_AD04h

0 L13_AD04i

-3 -2 -1 0 1 0 100 L13_AD04j

0 20 L13_AD00a

0 L13_AD00b

0 L13_AD00c

0 L13_AD00d

0 100 L14_AD04f

0 100 L14_AD04g

0 100 L14_AD04h

-3 -2 -1 0 1 0 100 L14_AD04i

0 L14_AD00a

0 200 L14_AD00b

0 L14_AD00c

0 40 L14_AD00d

0 100 L14_AD00e

0 100 L14_AD00f

0 100 L14_AD00g

0 20 L14_AD04a

0 L14_AD04b

0 L14_AD04c

0 20 L14_AD04d

0 L14_AD04e

0 L15_AD00a

0 40 L15_AD00b

0 200 L15_AD00c

0 200 L15_AD00d

0 200 L15_AD00e

0 L15_AD00f

0 L15_AD04a

0 L15_AD04b

0 80 L15_AD04c

0 L15_AD04d

0 200 L15_AD04e

-3 -2 -1 0 1 0 40

L15_AD04f

0 20 L16_AD04c

0 80 L16_AD04d

0 80 L16_AD04e

-3 -2 -1 0 1 0 200

L16_AD04f

0 200 L16_AD00a

0 L16_AD00b

0 L16_AD00c

0 L16_AD00d

0 L16_AD00e

0 100 L16_AD00f

0 L16_AD04a

0 L16_AD04b

0 L17_AD00a

0 100 L17_AD00b

0 L17_AD00c

0 100 L17_AD00d

0 40 L17_AD00e

0 L17_AD00f

0 L17_AD04a

0 100 L17_AD04b

0 200 L17_AD04c

-3 -2 -1 0 1 0 200 L17_AD04d

0 20 L18_AD00a

0 L18_AD00b

0 L18_AD00c

0 20 L18_AD00d

0 200 L18_AD00e

0 100 L18_AD00f

0 100 L18_AD00g

0 100 L18_AD04a

0 20 L18_AD04b

0 40 L18_AD04c

0 L18_AD04d

0 L18_AD04e

0 20 L18_AD04f

0 L18_AD04g

-3 -2 -1 0 1 0 L18_AD04h

0 200 L19_AD00a

0 L19_AD00b

0 40 L19_AD00c

0 100 L19_AD00d

0 100 L19_AD00e

0 40 L19_AD04a

0 200 L19_AD04b

0 L19_AD04c

0 L19_AD04d

-3 -2 -1 0 1 0 200 L19_AD04e

0 L20_AD00a

0 L20_AD00b

0 100 L20_AD00c

0 100 L20_AD00d

0 40 L20_AD00e

0 L20_AD04a

0 200 L20_AD04b

0 L20_AD04c

-3 -2 -1 0 1 0 L20_AD04d

Time to collision (s)

Multi-neuronal responses from locusts presented with complex object motion

John R. Gray and Paul C. Dick, Dept. Biology, University of Saskatchewan

B

135° 45° 90°

Ch 1 Ch 2 Ch 3 Ch 4

Unit 1

Unit 3

Unit 2 50 µm

2x2

tetrode

xs VNC

A

Neural

Data

Rear projection screen Recording set-up

C

Electrode configuration Spike sorting

Type responses to different trajectories

-1000 1000

-3 -2 -1 0 1

Time to collision (s)

0 100 200

L19_AD00a

-3 -2 -1 0 1

Time to collision (s)

L19_AD04e

Fir

ing r

ate

(sp

ikes

/s)

Sample responses to looming (red dashed outline)

Response No response

Multineuronal responses to looming from 90°

3 0

1 5

6 0

6 0

6 0

1 5

6 0

4 0 0

2 0

1 0 0

1 0 0

2 0

1 0 0

2 0

4 0

1 0 0

1 0 0

1 0

1 0

2 0

1 0

2 0

2 0 0

4 0

4 0

2 0 0

1 0

2 0

1 0

1 0

1 0

1 0

4 0

1 0

1 0 0

2 0

1 0 0

1 0 0

1 0 0

1 0 0

2 0

2 0

1 0 0

1 0

4 0

1 0

1 0

1 0

2 0

1 0

2 0

4 0

1 0

1 0

1 0 0

4 0

4 0

4 0

1 0 0

1 0 0

2 0

2 0

1 0 0

1 0 0

1 0

2 0

1 0 0

1 0 0

1 0

1 0

1 0 0

2 0

1 0

4 0

1 0 0

1 0 0

1 0 0

1 0 0

4 0

PCA results

Component

0 20 40 60 80 100 120 140 160

Eig

envalu

e

0

2

4

6

Cu

mu

lati

ve

% v

ari

an

ce

0

20

40

60

80

100

A

B Type 1 (TOC- )

Type 1? Type 2 (TOC- )

Type 5 (slow TOC- )

Type 3 (TOC- )

Type 4 (TOC- )

0

100

200

0

100

200

0

100

200

Fir

ing

ra

te(s

pik

es/s

)

0

100

200

0

100

200

0

100

200

Time to 90° (s)

-2 -1 0 1 2

0

50

100

Time to collision (s)

-3 -2 -1 0 1

Time to collision (s)

-3 -2 -1 0 1

Time to collision (s)

-3 -2 -1 0 1

Trajectory

(vector 1)

(vector 2)

Type 2 (vector 3)

Type 3 (vector 7)

Type 4 (vector 4)

Type 5 (vector 5)

Mean (n = 162)

Type 1

• Multiple locust neurons (mean = 8)

respond to a looming object.

• PCA reveals 5 response types based on

TOC-associated firing rate modulation.

• Response type activity reflects properties

of compound object motion.

• Future analysis and experiments will

examine relationships across types and

responses in flying locusts, respectively.

TTC (s)

-2.5 -2.0 -1.5 -1.0 -0.5 0.0

Mea

n F

irin

g R

ate

(sp

ikes

/s)

0

50

100

150

200

DCMD

LDCMD

DCMD (black) and LDCMD (red)

Response to a 7 cm disc looming towards

The center of the locust eye. Data aligned

to time to projected collision (TTC = 0 s).

From Gray et al. (2010).