1. Volume 94, Issue 4, Pages 855-865.e5 (May 2017)
Dopamine Depletion Impairs Bilateral Sensory Processing in the Striatum in a Pathway- Dependent Manner 
Maya Ketzef, Giada Spigolon, Yvonne Johansson, Alessandra Bonito-Oliva, Gilberto Fisone, Gilad Silberberg 
Neuron 
Volume 94, Issue 4, Pages e5 (May 2017)
DOI: /j.neuron
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2. Figure 1 MSN Classification Using the Optopatcher
(A) Optogenetic classification was obtained using either D1-ChR2-YFP (labeling dMSNs, top) and D2-ChR2-YFP (labeling iMSNs, bottom) mice. Note the projections to SNR in the D1-ChR2-YFP mice and to GP in the D2-ChR2-YFP mice.
(B) Paired recordings in a striatal slice from a D2-ChR2-YFP mouse showing responses in positive (ChR2+) and negative (ChR2-) MSNs to a train of blue light flashes.
(C) In vivo classification of MSNs using the optopatcher. Illustration shows optopatcher recordings containing an optic fiber and silver-chloride wire photostimulating the recorded MSN (right). Responses to light in D2-ChR2-YFP mouse (ChR2+, top) appeared as a depolarizing step for the duration of the stimulation superimposed by APs. Inset shows magnification of the light response onset. Negative cells (ChR2−, bottom) did not respond with depolarization.
(D) Examples of optopatcher responses in ChR2 positive (green, left) and negative (black, right) MSNs. A total of 20 sweeps are shown, superimposed by the average trace (pink).
(E) Example of light-intensity dependence of optopatcher responses in a ChR2-positive iMSN recorded in a D2-ChR2-YFP mouse.
(F) Summary of optopatcher responses of in vivo recorded MSNs (n = 70 cells). ST, Striatum; GP, Globus Pallidus; SNR, Substantia Nigra pars reticulata.
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3. Figure 2
Type-Dependent Changes in Intrinsic MSN Properties following DA Depletion
(A) A scheme of the experimental setting showing the timeline of 6OHDA MFB lesions and striatal whole-cell recordings in the same hemisphere following DA depletion.
(B) Coronal sections showing the striatal hemispheres of sham (left) and 6OHDA-lesioned (right) mice, stained for TH expression. Over 80% reduction in fluorescence was found between DA-depleted and control hemispheres (p < , n = 3).
(C) Examples of spontaneous, whole-cell voltage recordings from dMSNs in control (upper trace) and DA-depleted (lower trace) striatum. Analysis of the spontaneous slow oscillations is presented in Figure S3.
(D) Membrane potential of dMSNs in the down state of DA-depleted mice is more depolarized than it is in control mice (p = ; dMSN control n = 26, DA-depleted n = 15). No such difference is found in iMSNs (p = 0.590; control n = 16, DA-depleted n = 12).
(E) Input resistance of dMSNs in control mice was lower than that of control iMSNs (p = 0.05) and dMSNs in DA-depleted mice (p < 0.001).
(F) Spontaneous AP discharge frequency of iMSNs is higher than dMSNs in control animals (p = 0.05, dMSN n = 16, iMSN n = 11). This difference is absent in DA-depleted animals (p = 0.879, dMSN n = 6, iMSN n = 8).
For all panels, data are presented as mean ± SEM. Control iMSNs are in red, control dMSNs are in green, DA-depleted dMSNs are in light green, and DA-depleted iMSNs are in light red. ∗p < 0.05, ∗∗∗p <
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4. Figure 3
Laterality Encoding of Sensory Input Is Impaired following DA Depletion
(A) Grand average of responses of dMSNs in control (left) and DA-depleted (right) mice to contralateral (violet traces) and ipsilateral (magenta traces) whisker stimulation. Shaded areas represent the SEM. Schematic of whisker deflections in relation to the recording site (middle).
(B) Differences in response amplitude and peak delay of dMSNs between contralateral, C, and ipsilateral, I, responses (p < 0.001, n = 26, left) are abolished following DA depletion (p > 0.478, n = 15, right).
(C) Grand average of responses of iMSNs in control (left) and DA-depleted (right) mice to contralateral and ipsilateral whisker stimulation.
(D) Differences in response amplitude and peak delay of iMSNs between contralateral, C, and ipsilateral, I, responses (p < 0.02, n = 15, left) are diminished following DA depletion (p > 0.515, n = 9, right).
Control iMSNs are in red, control dMSNs are in green, DA-depleted dMSNs are in light green, and DA-depleted iMSNs are in light red. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p <
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5. Figure 4
Sensory Responses in Pyramidal Cells from Somatosensory Cortex Are Not Changed following DA Depletion
(A) The image and magnified inset show an example of a biocytin-filled pyramidal cell from S1 layer 5 following in vivo whole-cell recording. Scale bar, 125 μm. Inset shows the same cell in higher magnification. Scale bar, 25 μm. WM, white matter; ST, striatum.
(B) Spontaneous activity recorded in pyramidal cells of control (left) and 6OHDA-lesioned (right) mice.
(C) Grand average of responses of layer 5 pyramidal cells in control and DA-depleted mice to contralateral (violet traces) and ipsilateral (magenta traces) whisker stimulation. Shaded areas represent the SEM.
(D) Differences in response amplitude and peak delay of layer 5 pyramidal cells between contralateral, C, and ipsilateral, I, responses in control mice (p < 0.01, n = 13, left) are maintained following DA depletion (p < 0.01, n = 13, right). Data are presented as mean ± SEM. Black traces, boxes, and whiskers: control; gray traces, boxes, and whiskers: 6OHDA-lesioned. Magenta traces: ipsilateral responses; violet traces: contralateral responses. ∗∗p < 0.01, ∗∗∗p <
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6. Figure 5
Intrinsic Properties of MSNs and Corticostriatal Synaptic Responses Are Oppositely Changed by DA Depletion and Acute Blocking of Dopamine Receptors
(A) dMSNs and iMSNs were visually identified and simultaneously recorded in slices from D1/D2-tdTomato mice.
(B) Examples of voltage responses to current step injections from dMSNs (left) and iMSNs (right) of control (top) and DA-depleted (bottom) mice.
(C) DA depletion reduced differences in input resistance (left) and excitability (right) between simultaneously recorded dMSNs and iMSNs (control: n = 35 pairs, DA-depleted: n = 18 pairs). The changes in both properties were selective to the dMSN population (input: control versus DA-depleted, dMSNs p = 0.001, iMSNs p = dMSN versus iMSN, control p = 0.011, DA-depleted p = Minimum current to discharge: control versus DA-depleted, dMSNs p = 0.002, iMSNs p = dMSN versus iMSN, control p < 0.001, DA-depleted p = 0.143).
(D) Corticostriatal excitatory synaptic transmission from ipsilateral S1 to identified MSNs was studied by injecting AAV2-CamKIIa-YFP-ChR2 to primary sensory cortex (barrel field) of D1/D2-tdTomato mice (left). Whole-cell recordings were obtained from pairs and triplets of identified MSNs. Synaptic terminals were activated by blue LED stimulation from the microscope objective (right) in the presence of gabazine.
(E) Amplitudes of corticostriatal EPSPs in simultaneously recorded dMSNs and iMSNs from control mice (n = 16 pairs, left), DA-depleted mice (n = 15 pairs, middle), and control mice with bath application of DA blockers (n = 11 pairs, right) were not significantly different (p > 0.504).
(F) AMPA:NMDA ratio of excitatory synaptic responses in dMSNs and iMSNs following optogenetic stimulation of corticostriatal terminals from S1. Right: AMPA:NMDA is significantly different between dMSNs (control 5.60 ± 0.57, n = 15, DA-depleted 4.19 ± 0.65, n = 17, p = 0.041) but not iMSNs (control 4.03 ± 0.43, n = 17, DA-depleted 4.15 ± 0.50, n = 15, p = 0.856). Initial differences between responses in dMSNs and iMSNs (p = 0.033) were lost after DA depletion (p = 0.762).
(G) Grand average of postsynaptic corticostriatal responses to 20 Hz blue light pulses (2 ms) stimulation in dMSNs (left) and iMSNs (right) of control and DA-depleted mice. Overlaid average traces were normalized to the peak amplitude of the first light response (designated by black arrow).
(H) Examples of postsynaptic corticostriatal responses to trains of blue light stimulation (8 pulses, 20 Hz, 2 ms duration) in dMSNs (left) and iMSNs (right) of control animals before and after DA receptor (D1+D2) blocking (black traces). Overlaid average traces were normalized to the peak amplitude of the first light response (designated by black arrow).
(I) Summary of corticostriatal synaptic dynamics onto dMSNs (left) and iMSNs (right) under control (n = 26, solid circles), DA-depleted (n = 18, solid light color), and DA receptor blockage (n = 6, empty circles) conditions. For both MSN types, synaptic depression was significantly decreased by DA depletion compared to control and DA receptor block (p < 0.01 and p < 0.001, respectively). Data are presented as mean ± SEM. Control iMSN is in red, control dMSN is in green, DA-depleted dMSN is in light green, and DA-depleted iMSN is in light red. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p <
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7. Figure 6
Lateral Encoding of Whisker Responses Is Restored and Enhanced following L-DOPA Administration
(A) L-DOPA was administered for 4 days prior to whole-cell recordings, with the last injection at the day of the recording session.
(B) Grand average of responses of dMSNs (top right) and iMSNs (bottom right) in L-DOPA treated mice, to contralateral (violet traces) and ipsilateral (magenta traces) whisker stimulation. Shaded areas represent the SEM. Responses in control and DA-depleted mice are shown as reference (left and middle, in gray).
(C) Differences in response amplitude and peak delay of dMSNs between contralateral, C, and ipsilateral, I, responses are restored following L-DOPA treatment (p < 0.05, n = 12, left), but not in iMSNs (p > 0.157, n = 17, right).
(D) L-DOPA application restored the amplitude, peak delay, and slope of contralateral responses in dMSNs (top panel, p < 0.017). Responses in iMSNs were enhanced (p ≥ 0.07), but only the slope of ipsilateral responses reached significance (p = 0.025). Data are presented as mean ± SEM. Magenta bars and stars, ipsilateral responses in L-DOPA treated animals; violet bars and stars, contralateral responses in L-DOPA treated mice. ∗p < 0.05.
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