Optogenetic Activation of Direct-Pathway MSNs
Objective: To directly activate basal ganglia circuitry using optogenetic control of direct- and indirect-pathway medium spiny projection neurons (MSNs) and measure effects on motor behavior including freezing, bradykinesia, and locomotor initiation
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Equipment2
Materials1
Not specified • Not specified • Not specified • Not specified
Software1
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Protocol Steps
Viral vector preparation and injection
Prepare Cre-dependent viral expression vectors containing channelrhodopsin-2 for injection into striatum
Note: Vectors designed for Cre-dependent expression in D1-Cre and D2-Cre transgenic mice
View evidence from paper
“Cre-dependent viral expression of channelrhodopsin-2 in the striatum of D1-Cre and D2-Cre BAC transgenic mice”
Stereotaxic injection into striatum
Inject viral vectors containing channelrhodopsin-2 into the striatum of transgenic mice
Note: Bilateral injection to target both direct and indirect pathway MSNs
View evidence from paper
“Cre-dependent viral expression of channelrhodopsin-2 in the striatum of D1-Cre and D2-Cre BAC transgenic mice”
Optogenetic activation of indirect-pathway MSNs
Bilaterally excite indirect-pathway MSNs using optogenetic stimulation and observe resulting motor behavior
Note: Activation elicits parkinsonian state with increased freezing, bradykinesia, and decreased locomotor initiations
View evidence from paper
“Bilateral excitation of indirect-pathway MSNs elicited a parkinsonian state, distinguished by increased freezing, bradykinesia, and decreased locomotor initiations”
Optogenetic activation of direct-pathway MSNs
Activate direct-pathway MSNs using optogenetic stimulation and measure effects on motor behavior
Note: Activation reduces freezing and increases locomotion
View evidence from paper
“activation of direct-pathway MSNs reduced freezing and increased locomotion”
Testing in Parkinson's disease model
Apply direct pathway activation in a mouse model of Parkinson's disease to assess therapeutic potential
Note: Direct pathway activation completely rescued deficits in freezing, bradykinesia, and locomotor initiation
View evidence from paper
“In a mouse model of Parkinson's disease, direct pathway activation completely rescued deficits in freezing, bradykinesia, and locomotor initiation”