In this second chapter on neurosciences, material covered will include neuroendocrinology, neurotransmitter systems, and neurobiology of psychiatric conditions. In addition, neuropsychiatric disorders will also be discussed (including aspects of neurodegenerative conditions, select infectious diseases, and autoimmune conditions). Finally, there will be discussion regarding some principles of neuromodulation (including electroconvulsive therapy, transcranial magnetic stimulation, and deep brain stimulation).