Neuroscience is the scientific study of the nervous system and is concerned with the structure, development, function, chemistry, pharmacology, and pathology of the nervous system. Modern tools and technologies (e.g. molecular biology, electrophysiology, computational methods, etc.) led to the advancement of research on nervous system. As a result, neuroscience is now comprised of various branches. Systems neuroscience is one such branch, together with cellular neuroscience and molecular neuroscience. Unlike cellular and molecular neurosciences that are focused at the cellular and molecular aspects of a neuron, respectively, the systems neuroscience is concerned with how these neurons and synapses work together in complex neural networks that lead to higher level of brain processes such as language, memory, emotion, self-awareness, consciousness, mood, behavior, decision making, perception, attention, etc.
Systems neuroscience studies the function of neural circuits and systems. It is concerned with how the neurons behave when they are connected together in neural networks. It uses techniques and tools such as electrophysiology, in vivo imaging, fMRI, PET, etc. Apart from the fundamental processes of the nervous system, the systems neuroscience is also concerned with identifying novel ways to repair broken neural circuits in diseased conditions.