Figure 2. | An inhibitory corticostriatal pathway

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An inhibitory corticostriatal pathway

Figure 2.

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University of Texas at San Antonio, United States
Figure 2.
Download figureOpen in new tabFigure 2. Photostimulation of auditory CS-SOM projections elicits direct inhibition and modulates action potentials in striatal SPNs.

(a) Schematic depicting injection site using the SOM-Cre transgenic mouse line to transfect CS-SOM projections to the dorsal striatum with ChR2. Bottom, auditory cortex: AAV.ChR2.flex injection site. Top, dorsal striatum: red CS-SOM ChR2-tdTomato-positive axons. (b) Experimental paradigm for photostimulating ChR2-positive CS-SOM projections while recording from SPNs. (c) Bright-field (left) and epifluorescence (right) images of a slice containing the auditory cortex injection site for AAV.ChR2.Flex. (d) Bright-field (left) and epifluorescence (right) images of a slice containing the dorsal striatum showing expression of ChR2-tdTomato following injection of AAV.ChR2.Flex into the auditory cortex. (e) Left, bright-field image of neurons as seen in bright-field microscopy during patch recordings. Middle, high-resolution epifluorescence image of a biocytin-labeled SPN. The dashed box indicates the location of the image in the right panel. Right, high-resolution epifluorescence image of spines from the biocytin-labeled SPN. (f) Example of IPSCs recorded at 0 mV from an SPN before (red trace) and after application of ionotropic glutamate receptor antagonists (NBQX 10 μM, CPP 5 μM: magenta trace) and GABAA receptor antagonist (gabazine 25 μM: black trace). (g) Left, plot of onset latencies recorded in SPNs (n = 16) including group averages (± s.e.m.). Middle, plot of IPSCs peaks calculated for SPNs, including group averages (± s.e.m.). Right, plot of IPSCs charge transfer calculated for individual IPSCs for SPNs, including group averages (± s.e.m.). (h) Left, example of IPSCs (black trace) and rising time course (red trace) recorded at 0 mV from an SPN. Right, plot of IPSCs rising time course recorded in SPNs (n = 16) including group averages (± s.e.m.). (i) Left, example of IPSCs (black trace) and decay time course (amber trace) recorded at 0 mV from an SPN. Right, plot of IPSCs decay time course recorded in SPNs (n = 16) including group averages (± s.e.m.). (j) Left (black trace), response of an SPN in the whole-cell current-clamp configuration to current injection (250 pA, 500 ms; n = 6). Left (blue trace), response of the SPN to current injection with photostimulation of CS-SOM projections (blue bar, 5–20 ms). Right (black trace), response of an SPN in the whole-cell current-clamp configuration to current injection (350 pA, 500 ms; n = 6). Left (blue trace), response of the SPN to current injection with photostimulation of CS-SOM projections (blue bar, 5–20 ms). (k) Summary of ChR2-mediated delay of action potential generation in SPNs (n = 6) during current injection combined with photostimulation of the ChR2 CS-SOM projections. Delay was relative to the onset of the first action potential measured during the current injection alone.

DOI: http://dx.doi.org/10.7554/eLife.15890.004