Parkinson's disease is a motor and cognitive neurodegenerative disorder associated to the progressive loss of Substantia Nigra pars compacta dopaminergic neurons. One cause of the disease is associated with the spreading of α-synuclein aggregates. Recent findings indicate that extracellular α-synuclein oligomers represent the most neurotoxic species and reduce the firing discharge of midbrain neurons, impair network synchronization, up-regulate Cav2.2 Ca channels and neurotransmitter release in cortical neurons. Here we combined conventional electrophysiology (current-clamp) and diamond multiarray prototypes respectively to investigate the effect of extracellular α-synuclein oligomers on the firing discharge and the quantal dopamine release in Substantia Nigra dopaminergic neurons. Primary cultures were exposed for 48 hours to α-synuclein: this caused a drastic decrease of the spontaneous firing discharge, from 3.7 to 1.7 Hz and altered action potential waveform. Interestingly, the spontaneous firing discharge of α-synuclein-treated neurons was restored to control values after blocking Cav2.1 and Cav2.2 Ca channels by ω-conotoxin MVIIC. As these channels are involved in dopamine release, and dopamine exerts a D2-mediated inhibition of the firing discharge, we investigated whether α-synuclein could also affect quantal release. Taking advantage of diamond multiarrays, that allow to perform simultaneous amperometric recordings from 16 sensing electrodes, we measured dopamine release both under control conditions and after 48 hours exposure to α-synuclein. We found that α-synuclein significantly increased the frequency of quantal release events, from 0.25 to 6.96 Hz. These data suggest that α-synuclein exposure significantly affects the interplay between dopamine release and spontaneous firing activity in Substantia Nigra dopaminergic neurons.