In-vivo voltammetry has successfully been used to detect dopamine release in rodent brains, but its application to monkeys has been limited. We have previously detected dopamine release in the caudate of behaving Japanese monkeys using diamond microelectrodes (Yoshimi 2011); however it is not known whether the release pattern is the same in various areas of the forebrain. Recent studies have suggested variations in the dopaminergic projections to forebrain areas. In the present study, we attempted simultaneous recording at two locations in the striatum, using fast-scan cyclic voltammetry (FSCV) on carbon fibers, which has been widely used in rodents. Responses to unpredicted food and liquid rewards were detected repeatedly. The response to the liquid reward after conditioned stimuli was enhanced after switching the prediction cue. These characteristics were generally similar between the ventral striatum and the putamen. Overall, the technical application of FSCV recording in multiple locations was successful in behaving primates, and further voltammetric recordings in multiple locations will expand our knowledge of dopamine reward responses.
Voltammetric recordings of behaving monkeys
Each folder contain data files of one experimental day.
Original COLOR.txt files.
Each FSCV recording consists of 500 voltage points for 10ms (50kHz sampling).
Recording was repeated at 10Hz, every 0.1s.
In MFB stimulation, each trial was made for 20s (200 time points) and the electrical stimulation was delivered from 5s (from recording 50).
Original COLOR data of MFB stimulation is a table of 200 x 500.
In behavioral analysis, each recoring was made for 300s block (3000 time points), simultaneously for 4 channels.
In most cases, Ch0:ventral striatum (acc, Cd), Ch1:putamen, Ch3:CS signal and Ch4:IR sensor monitoring the facial movement.
To export full waveform data of multi-channel recording on TH-1, backgound subtraction was turned off.
The original data, recorded as nA value, was exported as COLOR.txt files.
Original COLOR data of behavioral task is a table of 3000 x 500.
CS signal was simultaneously recorded on Ch2, and the CS timing during 300s block was exported as IT.txt files.
The hight of CS signal indicate the type of trials, and the offset of CS is the timing of juice delivery.
For free trials, similar timing signal is recorded and the juice was delivered at the offset of the signal, but no visual stimuli appeared on the screen.
Original ITCS data of CS is a table of 3000 x 1.
For food trials, the pulses in ITCS data indicate the timing of reaching of the food to the mouth.
These data were loaded on MATLAB, background subtracted for each trials, and PCR was performed using princomp function.
Templates for Principle Component Regression (PCR) analysis.
Voltage-current curves (500 points) at the peak MFB responses were collected as in-vivo dopamine template.
Also, presumably pH curves were collected 10-15s after the stimulation.
Result of PCR: 1zz, 2zz and 3zz files, each columns indicate one trial for 8s (80 points).
Each column started with the Block number, timing point of CS onset in the block and hight of CS signal.
The trials judged as "extreme" have more than 1000 value of CS signal.
1zz is the dopamine-like component and 2zz is the pH-like component.
3zz is the current at the peak of dopamine oxidation potential (120/500 points)
Point 40 is the CS onset. Timing cue was shown from point 30, and the onset of juice delivery was point 55.
One behavioral session consists of multiple 5-min blocks.
Review on EXEL show the average of each trial type within the session.
In original analysis to calculate PCR result of 1zz, timing of the trials were aligned by CS onset, so time 0 is the time just before the CS onset.
For final graph presentation of the results, the timing of juice delivery/CS offset is shown as time 0.
In some review tables of EXEL, you need to find which timing determination is applied.