Complex sentence: There is evidence for increased activity of the mesolimbic pathway, a dopaminergic pathway, in schizophrenia patients, this comes from the discovery of increased L-DOPA decarboxylase levels in the brains of these patients.
Split into simpler sentences: There is evidence for increased activity of the mesolimbic pathway, a dopaminergic pathway, in schizophrenia patients. This comes from the discovery of increased L-DOPA decarboxylase levels in the brains of these patients.