Extended Data Fig. 1. Recording, photolabeling and classification of the VTA DA neurons.
(a) Picture of the microdrive implanted in DAT-Cre mice with recording electrodes and optic fiber. (b) Schema of the implantation of the microdrive in the VTA. (c) Representative coronal image of immuno-staining experiments against Tyrosine Hydroxylase (TH) enzyme (red) performed on midbrain slices of DAT-Cre adult mice infected with AAV5-Ef1α-DIO-ChR2-eYFP (green) in the VTA. (d) Picture of an implanted mouse for freely behaving recording. (e) Top: Example trace of a VTA DA neuron following optogenetic light stimulation protocol at 20Hz. Down: Example of waveforms similarity between light stimulation and no-light stimulation of a photolabeled VTA DA neuron. (f) Example PETH centered to the light pulse (top), of a VTA DA neuron responding to the 20Hz protocol stimulation with the corresponding raster plot for all the trials (down). (g) Averaged PETH, centered to the light pulse, for all the VTA DA neurons following the optogenetic protocol at 5Hz stimulation. (h) Averaged PETH, centered to the light pulse, for all the VTA DA neurons following the optogenetic protocol at 20Hz Stimulation. (i) Probability to have a spike in the 10ms following the beginning of the light pulse for 5Hz and 20Hz protocols. Paired t-test two-sided (t(16) = -8.2603). (j) Time course of all the photolabeled VTA DA neurons before, during and after the 20Hz protocol stimulation. (k) Mean firing rate of the VTA DA neurons at baseline (without optogenetic stimulation) and during optogenetic stimulation at 20Hz. Responders are represented in blue while non-responders to the light stimulation are in black (example of 2 neurons). (l) Waveforms examples of different neurons after spike-sorting for VTA-pDA (Left), VTA-nonDA high firing (Middle) and VTA-nonDA low-firing (Right) neurons. The red line represents the average of all the waveforms recorded during a session for one neuron. (m) Firing probability density for 3 different neurons (VTA-pDA, VTA-nonDA high firing and VTA-nonDA low-firing). This probability is the Log10 of the instantaneous frequency for a given neuron, and allows to extract general features such as tonic and bursting activity by using Robust Gaussian Surprise method. (n) Examples of traces for the 3 different neurons types with the tonic, bursting and pause activity. (o) Left: Dimensionality reduction with UMAP (Uniform Manifold Approximation and Projection) based on features extracted from firing pattern (see methods) followed by EMGM (Expectation Maximization of Gaussian Mixture) clustering based on VTA-DA photolabeled neurons. The neurons can be dopaminergic (VTA DA photolabeled), putative dopaminergic (VTA pDA) or putative non-dopaminergic (VTA non-pDA). Right: pie charts show inclusion or exclusion of previously identified neurons in the VTA DA cluster.
n indicates the number of cells. Dots represent individual data points. All the data are shown as the mean +/-s.e.m. as error bars.