Science - 31 January 2020

of double-labeled SPNs (Fig. 4, H and I, and
table S4). The percentages of double- and single-
labeled neurons indrd1a-Cre mice matched
those previously observed with the nonswitch-
able virus indrd2-eGFP (i.e., 20 and 80%;
compare Fig. 4, E and I). Again, these same
proportions were consistently found across
all infected striatal areas analyzed, irrespec-
tive of the area of spread (fig. S7, C to E). The
two major projection systems in the striatum
establish very different local connectivity,
with D2-SPNs making substantial connec-
tions with D1-SPNs but not vice versa. The
magnitude of this asymmetry provides full
neuroanatomical support for the large-scale
D2- to D1-SPN transmodulation observed in
this study.

To address the functional relevance of this

connectivity bias, we evaluated the effects of

RAC and GBR cocktail on striata where D2-SPNs

had been genetically ablated in the DMS (fig.

S8, A and B). After recovery, mice with unila-

teral D2-SPN depletions (Fig. 4J) were treated

with RAC and GBR prior to perfusion (as in

Fig. 3B), and patterns of transcriptional acti-

vation were contrasted between control and

lesioned sides. The density of taD1-SPNs was

inversely proportional to the density of D2-

SPNs in control and lesioned sides (Fig. 4K and

table S4). Analysis of P-H3+nuclei across con-

tiguous striatal territories spanning lesioned

and intact areas revealed that the identity of the

transcriptionally active neurons transitioned

from D2-SPNs (in intact territories) to D1-

SPNs (in D2-ablated territories) (Fig. 4L). Sim-

ilarly, D2-SPN removal in the DMS opened

windows of uncontrolled D1-SPN activation

(fig. S8C).

D2-SPNs shape other sources of flexibility in

goal-directed learning

Thus far, our results suggest that D2-SPNs shape

the changes in striatal plasticity necessary for

flexible encoding of goal-directed learning. In

the case of inhibitory learning during extinc-

tion, this process is compatible with the role

ascribed to DA in negative prediction error

scenarios: A sustained pause of phasic DA in

defined striatal territories may lead to recruit-

ment of D2-SPNs and, with it, the D2-to-D1

transmodulation reported here. We next sought

Matamaleset al.,Science 367 , 549–555 (2020) 31 January 2020 5of7

Fig. 4. SPN subtypes show large-scale uni-

directional transconnectivity.(A)Anterograde

transsynaptic HSV1-H129-tdTomato virus was

unilaterally injected in the posterior striatum of

drd2-eGFP mice. (B) In a hypothetical striatum

with symmetrical SPN-SPN contacts, the

“founder”cells first integrating the virus are

expected to infect similar proportions of

surrounding SPNs (D2 and D1). (C) Infected,

Td-Tomato+, particles were classified as

D2- and D1-SPNs according to their eGFP and

DARPP-32 content (fig. S6A). (D) Digitized

reconstruction of infected D2- and D1-SPNs in

an entire striatal hemisection. (E) Percentage

of particles classified as D2- and D1-SPNs

(fig. S6, B to D) (10 hemisections, five mice).

(F) HSV1-H129Floxedvirus (permanently

switches from eGFP to tdTomato if it

encounters Cre) was bilaterally injected in the

striatum ofadora2a-Cre anddrd1a-Cre mice.

(G) Infection in cis involves infection through

isolated lineages (green and red). Infection in

trans involves infection across lineages (yellow;

see materials and methods). (H) Viral spread

and digitized reconstruction of red-labeled

(tdTom) and yellow-labeled (tdTom + eGFP)

SPNs in entire striatal hemisections of each

Cre line. (I) Percentage of red and yellow

SPNs in each Cre line (fig. S7) (13 to

16 hemisections in four mice per line).

(J) Unilateral genetic lesion of D2-SPNs in

the DMS (as in Fig. 2G). (K) Quantification of

D2-SPN density (left axis) and taD1-SPN

density (right axis) in control and lesioned

sides after Rac + GBR pharmacological

treatment (Fig. 3B) (five mice). (L)Medio-

lateral continuum from lesioned to intact

striatal territories after drug treatment.

Bottom: green (eGFP) and red (P-H3)

fluorescence plot profile across the medio-lateral

continuum above. m.g.v, mean gray value. *,

significant overall/simple effect (black) and

interaction (red). n.s., not significant (table S4).

500 px

x

y

500 px

x

y

0 20 40 60 80 100

0 20 40 60 80 100

tdTom

tdTom + eGFP

D1-SPN

D2-SPN

Infected

1 cycle n cycles

Filtered particles, %

Cre

Cis infection: Trans infection:

Filtered particles, %

A D

FH

G

C

B

E

I

JL

K

drd2-eGFP

drd1a

• Cre

adora2a

• Cre

drd2

• eGFP

D1-SPN

D2-SPN

D1

tdTom

tdTom+eGFP

drd1a

• Cre

adora2a

• 
  

Cre

D2

tdTom + eGFP

+ DARPP-32 Filtered

HCMV

eGFPSV40pa tdTom

LoxP

H129

CMVpa

+ Cre

HCMV

tdTom

H129

CMVpa

HCMV

H129 tdTomSV40pa

Infection founders

C

CC

C

C

AAV-FLEx-

taCasp3-TEVp

adora2a-Cre::drd2-eGFP

Lesioned

+eGFP

P-H3

Intact

0

100

200

300

400

500

Density (ROIs/mm^2 )

Control Lesioned

0

200

400

600

800

m.g.v.

Control Lesioned

tdTom

tdTom

n.s.

D2-SPNs

taD1-SPNs (P-H3+)

L

D

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