Neurophysiology is a branch of physiology and neuroscience that is concerned with the study of the functioning of the nervous system. The primary tools of basic neurophysiological research include electrophysiological recordings such as patch clamp and calcium imaging, as well as some of the common tools of molecular biology. Neurophysiology is connected with electrophysiology, neurobiology, psychology, neurology, clinical neurophysiology, neuroanatomy, cognitive science, biophysics, mathematical biology, and other brain sciences. .Clinical neurophysiology provides a range of important investigations to help in the diagnosis and management of patients with neurological disease. Neurophysiological techniques allow us to study the current activity of the nervous system. In daily clinical practice, these recordings are very helpful in the diagnosis of neurological diseases such as epilepsy or neuropathies. The Department of Clinical Neurophysiology at the NHNN is responsible for a wide range of neurophysiological procedures, principally electromyography (EMG) and nerve conduction studies, EMG-guided botulinum toxin (BoTox) injections, electroencephalography (EEG), evoked potentials (EPs) and intra-operative monitoring (IOM). The department is recognised as a centre of excellence, with an international reputation for pioneering new techniques to investigate nervous system function, and has a major role in the training of neurophysiologists, neurologists, clinical physiologists and researchers. The department offers a number of specialised techniques, including investigation of ion channel disorders affecting peripheral nerve and muscle, examination of small fibre properties using quantitative sensory testing, laser Doppler Imaging and skin biopsies. Development of new neurophysiological techniques in combination with fMRI in the study of facial pain and headache.