Manganism, a movement disorder characterized by neuronal death in the basal ganglia and symptomatology similar to Parkinson’s disease, has been shown to involve manganese-mediated increase of toxic reactive oxygen species (ROS) production in mitochondria. The protein alpha-synuclein, a product of the SNCA gene, has been implicated in glial and neuronal degeneration in Parkinson’s disease, and preliminary data from our laboratory suggests that removal of alpha-synuclein from astrocytes confers some protection against ROS toxicity. Astrocytic hydrogen peroxide metabolism has been shown to produce ROS capable of damaging a variety of cellular macromolecules. The present study seeks to compare the effectiveness of toxicant attenuation in SNCA knock-out and wild type astrocytes in response to hydrogen peroxide after gradated 24-hour manganese pre-treatments. Calcium imaging with fluo-4 dye will be performed to measure astrocytic calcium by quantifying the amplitudes and durations of induced calcium waves, known to form an important mechanism of astrocytic communication, after addition of hydrogen peroxide. Based on previous studies, we predict that increased manganese dosages will correlate with elevated calcium wave amplitudes in both SNCA knock-out and control cultures. We further predict significantly lower calcium wave amplitudes in wild type cultures after each manganese treatment.