Which area of neuroscience\biology deals with the effects of genetics and drug discovery based on brain microcircuits?
Basically you are sketching a situation where:


Brain circuits are modeled (Computational Neuroscience), which often depends on anatomical (Neuroscience, Biology), structural imaging and functional imaging (Neuroimaging) and electrophysiological data (Electrophysiology). Various other disciplines may come into play (Histology, Pathology, Anatomy, etc.). 
Genetic (Genetics, Molecular Biology, Cell Physiology) and environmental effects (Behavioral Psychology, Medicine, Psychiatry) also encompass a wide list of expertise, out of which a small handful is mentioned in bold.
The realm of drug discovery harbors Medicine, Toxicology, Organic Chemistry, Pharmacology, perhaps even Physics and likely a host of others.


In short, your question could, perhaps, better be phrased as 'What Biomedical fields of research disciplines are not related to Drug Discovery?