Has anybody use micrelectrode (33um diameter) to do FSCV to test dopamin in invivo?
I can't get the sitimulated singnal of DA in striatum.
You would need to provide more details of your methods to get a useful answer.
There are plenty of published papers measuring DA release using FSCV in vivo. Most use 7-10 um diameter fibers. The problem with larger fibers tends to be saturation of the amplifier headstage with large background currents observed under FSCV conditions.
So you have to indicate whether you are reliably detecting DA in vitro with these fibers, and then try to troubleshoot the in vivo conditions. Anything ranging from stimulator positioning, to loss of the integrity of the carbon fiber-glass seal during electrode implantation, can lead to difficulties in vivo.
If you can detect in vitro, then it should be suitable for in vivo recordings.
I assume if you are recording in dorsal striatum, you are placing a stimulating electrode in the medial forebrain bundle? I think most groups gradually position the stimulating electrode to optimize the signal (see attached link). You also have to keep a close eye on the background current following implantation to make sure the fiber/glass seal is still intact (or you could use fused silica as Philips and colleagues--- see link below).
https://www.ncbi.nlm.nih.gov/pubmed/21204389
https://www.ncbi.nlm.nih.gov/pubmed/28127962
I still can not get a dopamin signal after stumulation of either the MFB or VTA. I have read in others' paper that "Decreases in current below baseline following dopamine release,
especially after stimulated release, are most likely attributed to shifts in pH." and I did met with a decreases in the current when scaning to +1.3V. Coud anybody tell me is it important and is it possible to make DA signal disapper? I will appreciate it a lot if anyone can come up to help!
To get dopamine release, you need to use a good stimulating electrode. It must be securely insulated along the entire length except the end, so that there is no leakage of stimulating current. Check also if there is a leakage current on the dry electrode outside the brain.
I think you should stimulate SN, not VTA, if you want to see dopamine release in the dorsal striatum.
Dear Ruby Du,
The question was asked a long time ago. So have you got dopamine response at last? As for monopolar stimulation, we are working with it in vivo. This works well. I mean monophasic stimulation with a bipolar electrode.
Dear Valery Nikolaevitch Mukhin
I am so excited to tell you that I have made it today. I use a monopolar stimulation with width of 4 ms and get good result, yes with bipolar electrode, while shorter ones faild. I suppose that's one of the problems.
Thank you again for your kind guidance!
Dear Ruby Du,
Congratulations!!! I manage to get response to stimulation of 2 ms, frequency of 60 Hz, 60 pulses. What is frequency of stimulation do you use?
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