superficial layers of SC overlapped (see materials
and methods and figs. S1B and S9). SC silencing
almost completely abolished the response of POR
to the dots (Fig. 3D) (93.77 ± 1.95% average de-
crease ± SEM in visually evoked firing rate;P<
0.0001, Wilcoxon signed-rank test,n= 96, 5 mice),
across cortical depths in a homogeneous manner
(fig. S10). The reduction of POR responses to dots
was particularly pronounced for the portion of
the POR receptive field that overlapped with thereceptive field silenced in SC. That was evident
for dot trajectories covering a large fraction
of visual space, where SC silencing created a
“scotoma”in the response of POR neurons
(fig.S9).TodirectlycomparetheeffectofSCBeltramoet al.,Science 363 ,64–69 (2019) 4 January 2019 2of6
1 mmV1
PPORLILMALRL
PMPOR firing rate LED OFF (Hz)POR firing rate LED ON (Hz)Azimuth-45° 0° +45°0°+45°-45°Elevation0°+45°-45°ElevationAzimuth-45° 0° +45°PLI
LMALAMA
RLPORPMV1LEDV1
Rec.
POR
Rec.POR V1Rec. Rec. LEDV11mm 300 μm 100 μmDistance from bregma (mm)-3.0 -2.6 -2.2 -1.80.00.20.40.60.81.0PulvinardLGN
Fraction of total CTB+ cellsin Pulvinar and dLGNPORBregma: -4.5 mm Bregma: -2.6 mmV1dLGNPulvinarABC DEV1 PORV1 firing rate LED ON (Hz)V1 firing rate LED OFF (Hz)anterograde AAV1-CAG-TdTomatoanterograde
AAV1-CAG
TdTomatoretrograde
CTBGAD-Cre
AAV9-Flex-ChR2
injected in V1anteriorposteriorlateral medialposteriorlateral medialmin max
Firing rate
min max
Firing rateIdentification of higher visual areas Silencing V1 while recording in PORvisual thalamus?
FG0012468002468101520246810 15 20 12468LED0816Firing rate (Hz)
-1 0+ 1single unit-0.5 +0.5
Time from stimulus onset (s)LED08160single unit-1 -0.5 +0.5 +1
Time from stimulus onset (s)Normalized firing rateV100.20.40.60.8
LED0 +1average-1 -0.5 +0.5
00.20.40.60.8
LEDNormalized firing ratePORaverage-1 -0.5 0 +0.5 +1
Time from stimulus onset (s) Time from stimulus onset (s)PORFig. 1. Visual responses in POR are not driven by the geniculate-V1
pathway.(A) Injection of the anterograde tracer AAV1.TdTomato in
V1 enabled the visualization of higher visual areas. Delineated cortical
areas are as shown in fig. S2. The weaker fluorescence of POR is consistent
with its weaker V1 input ( 31 ). (B) Drifting gratings (diameter, 20°) were
presented to awake mice conditionally expressing ChR2 in V1 inhibitory
neurons. Recordings were simultaneously performed in POR and in
V1. A light-emitting diode (LED)–coupled optic fiber was used to
silence V1. (C) Example experiment. (Left) V1 recordings; (right) POR
recordings. (Top) Heatmaps of the receptive fields of multiunit activity.
Dotted circle shows position of the visual stimulus. (Bottom) Raster plots
and PSTH of RS units under control conditions (black) and during V1
silencing (blue). Black horizontal bar, duration of stimulus presentation;
blue horizontal bar, period of V1 silencing. (D) Summary of all experiments
as described for (C) (33 non-GABAergic RS units in V1 and 41 RS units
in POR from five animals). (Top) Summary average PSTHs. The PSTH
values for individual units were normalized by their maximum value and
then averaged together. (Bottom) Scatter plots reporting the responses
of all units measured during the stimulus presentation period (0.9 s).
Green data points, example units in (C). (E) Injection of the retrograde
tracer CTB in POR. (F) (Left) TdTomato injection site in V1 with
anterograde projection to POR (white) and CTB injection in POR (red).
(Middle) CTB+ neurons in dLGN and pulvinar nuclei. (Right) Higher-
magnification image of the region delineated by the square in the middle
image. (G) Distribution of retrogradely labeled dLGN and pulvinar neurons
along the thalamic rostro-caudal axis (ratio of CTB+ cells in pulvinar or
in dLGN to the total CTB+ cells counted in the two nuclei; 45 coronal
sections, three mice).RESEARCH | REPORT
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