Science - USA (2019-01-04)

3 mice) and drifting gratings (fig. S11) (92.46 ±
3.79% average decrease in visually evoked firing
rate;P< 0.0001, Wilcoxon signed-rank test,n=39,
3 mice). Baseline activity in POR was unaffected,
indicating that the suppression of visual responses
was not due to a direct action of TTX on POR.
Compared with V1, does POR capture distinct
properties of the visual world? The ability to

respond to small objects moving in the field of

view is a characteristic property of the SC ( 21 ).

We compared the response of V1 and POR to

small moving objects. The response of a neuron

to a dot moving on a monitor may report differ-

ent aspects of the stimulus. In one case, the neu-

ronal response may simply report local changes

in luminance within the neuron’s receptive field

that occur as the dot moves along its trajectory.

If so, the exact sequence of the changes in lumi-

nance along the trajectory may not be relevant

for eliciting a response. In the other case, the

neuron may selectively respond to the motion

of the dot, i.e., to changes in luminance occurring

sequentially at adjacent spatial positions. We

therefore presented two different stimuli: a

Beltramoet al.,Science 363 ,64–69 (2019) 4 January 2019 5of6

Fig. 4. POR neurons
discriminate moving
dots from random
dots.(A) (Left)
The stimulus was
a dark dot moving for
1 s at a speed of
30° per second along
a straight trajectory.
(Middle) Random dot:
The stimulus was
made of the same
frames as the
moving dot but
was presented in
random order. Each
iteration showed
a different random
sequence. (Right)
Recordings were
performed in V1 or
POR. (B) Raster plot
and PSTH of a V1 unit
in response to a
moving dot (left) or a
random dot (middle),
and the scatter plot
(right) of average
firing rates of V1 units
during the period of
stimulus presentation
(1 s) for moving
versus random dots
(67 units, five animals).
Green data point,
example unit shown
on the left. (C)As
in (B) but for POR
(56 units, five animals).
Note that the shown
POR unit did not
respond to random
dots. (D) (Left) ROC
curve for the V1
isolated unit shown
in (B). (Inset)
Distribution of spikes
for moving dots
(black bars) and
random dots (red
bars). (Middle) ROC
curve for the POR
isolated unit shown
in (C). (Right) Comparison of area under ROC curve (average ± SEM) for all responsive POR and V1 units. Black filled data points denote
P< 0.001 for difference in spike distributions between responses to moving and random dots (Wilcoxon rank sum test). Gray bars
show areas under ROC: for V1, 0.55 ± 0.007, 67 units, five mice; for POR: 0.69 ± 0.015, 56 units, five mice (P< 0.0001, Wilcoxon
rank sum test). Green data points, example units shown in (B) and (C).

B

D

C

POR

A

0 4 8 12

0.8

0

0.8

0 0.2 0.4 0.6 0.8 1

0

0.2

0.4

0.6

0.8

1

Fraction of trials

Spikes

Random

Moving

V1 p(Random Dot > cut-off)

V1 p(Moving Dot > cut-off)

V1

0 4 8 12

0.8

0

0.8

0 0.2 0.4 0.6 0.8 1

POR p(Random Dot > cut-off)

0

0.2

0.4

0.6

0.8

1

POR p(Moving Dot > cut-off)

Fraction of trials

Spikes

Random

Moving

0

4

8

0

4

8

0

4

8

Firing rate (Hz)

Firing rate (Hz)

V1

POR

Moving Dot

Moving Dot

Moving Dot

Random Dot

Random Dot

Random Dot

0

4

8

Firing rate (Hz)

Firing rate (Hz)

1

2

3

...

60

6

21

3

11

...

V1

Rec.

POR

Rec.

0.4

0.6

0.8

1

POR

Area under ROC

p<0.001

p>0.001

0.5

0.7

0.9

V1

POR firing rate - Random Dot (Hz)

0 123 4

0

1

2

3

4

10

10

20

20

POR firing rate - Moving Dot (Hz)

V1 firing rate - Random Dot (Hz)

0 123 4 5

0

1

2

3

4

5

10 20

10

20

V1 firing rate - Moving Dot (Hz)

5

5

-1 0 +1 -1 0 +1

-1 0 +1 -1 0 +1

Time from stimulus onset (s) Time from stimulus onset (s)

Time from stimulus onset (s) Time from stimulus onset (s)

RESEARCH | REPORT

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