Next, to identify the neuron types in the vlPAG that send afferent synapses to the wFMNs, the brain sections including the vlPAG from animals sacrificed at 72 h following PRV-EGFP infection were immunolabelled using excitatory (Ca2+/calmodulin-dependent protein kinase type II (CaMKII)), inhibitory (glutamate decarboxylase 1 (GAD67)), dopaminergic (tyrosine hydroxylase (TH)), and serotonergic (tryptophan hydroxylase 2 (TpH2)) neuronal markers (Fig. 4d and Additional file 2: Fig. S7). This evidence concerns the gene GAD1 and infection.