Although brain dysfunction has a series of clinical symptoms, no tissue structure abnormality is visible, thus making diagnosis and treatment difficult. The advent of neuromodulation has not only changed the traditional treatment model of resection and destruction, but also brought new hope to these patients. Functional brain diseases are difficult to diagnose and even more difficult to treat. As the most advanced and complex human tissue and organ, all functions of the brain rely on the interaction of bioelectrical and chemical transmitters among a huge number of neurons. When these interactions go wrong, such as excessive local electricity, increased firing or changes in the direction of transmission, a series of disease symptoms will be triggered, which are then called functional brain disorders. The reason why functional brain diseases are called functional, as opposed to organic diseases, is that it is often difficult to detect lesions on routine examination. This does not mean, of course, that the tissue structure is “normal”, but that the lesions are too subtle to be identified by the available tests. Functional brain disorders are usually characterized by chronic onset, prolonged course, and paroxysmal recurrent onset. Because of the wide distribution of the human nervous system, when its function is disrupted, the clinical symptoms are often diverse and complex, and difficulties in diagnosis and treatment are very common. Some common and typical brain disorders, such as epilepsy, Parkinson’s disease, pain, dystonia, and psychiatric disorders, require theories at the “neural network” level to explain. These disorders are characterized by their intractable and prolonged course, causing tremendous physical and mental suffering to patients. Neuromodulation A more minimally invasive treatment concept The treatment of neural networks is called neuromodulation, or neural network surgery, because it usually requires surgical techniques. Neuromodulation is the most rapidly developing discipline in medical science in the last 20 years, and it has brought about disruptive changes in the treatment of many diseases thanks to advances in medical biology and medical engineering. Neuromodulation is broadly defined as a therapeutic modality at the neuroscientific level that obtains therapeutic effects by altering the function or state of the nervous system in an electrical or chemical manner. Precisely, it is a method that uses electrical or chemical means, through implanted or non-implanted devices, to ultimately produce therapeutic effects by affecting signaling, excitation, inhibition, or modulation of neuronal and neural network activity in the nervous system. With these techniques, there has been a gradual transition from traditional resection-based neurosurgery to a surgical treatment model that targets neural networks for highly specific neurological modulation and remodeling. Deep electrical stimulation regulates local microcurrents Neuromodulation therapy, currently achieved mainly by electrical stimulation, is the use of low-level chronic stimulation to produce therapeutic effects on the nervous system, including the brain, spinal cord and peripheral nerves. The exact mechanism of deep brain stimulation is not yet clear, and possible mechanisms include depolarization blockade, channel blockade, and synaptic inhibition. At present, deep brain stimulation has begun to be used in the clinical treatment of movement disorders, chronic de-afferent pain, cluster headache, epilepsy and some psychiatric disorders, and has gained initial recognition. Deep brain stimulation is currently a more definitive method for the treatment of movement disorders and pain. Other sites of electrical stimulation include: spinal cord stimulation for pain; sacral nerve stimulation to control urinary and bowel function by stimulating the sacral nerve; vagus nerve stimulation for the control of seizures associated with epilepsy and for the treatment of depression. Implantation of drug delivery pumps Low-dose and efficient means Neuromodulation can also be achieved by means of direct drug delivery through implantation of pump devices at precise locations. Since the drug acts directly locally, the dose administered is effectively reduced, side effects are reduced, and the therapeutic effect is more assured. Long-term intrathecal administration of baclofen via implanted pumps has become the basic treatment for severe refractory spasticity of spinal or cerebral origin. Intrathecal opioid therapy was initially used for malignant pain. In general, pain is sensitive to opioid therapy, but oral or intravenous opioid therapy has not been accepted due to increased systemic side effects, such as nausea, vomiting, constipation, or central nervous system depression. Intrathecal application of drugs targeting presynaptic and postsynaptic receptors in the dorsal horn of the spinal cord has the advantage of proximity to the receptor sites and a reduced incidence of side effects due to the longer duration of therapeutic effect and smaller applied dose compared to intravenous systemic administration. The use of neuromodulation technology to target the neural network for the treatment of functional brain diseases is the most cutting-edge direction for the future development of functional neurosurgery and is expected to revolutionize the field of functional neurosurgery, which deserves further research. Neuromodulation directions of exploration Epilepsy Due to the abnormal discharge of neurons, resulting in the dysfunction of some or even the entire neural network, clinically manifested as complex and variable recurrent paroxysmal brain function abnormalities. Parkinson’s disease The specific clinical symptoms occur mainly due to abnormally elevated excitability of specific neurons for various reasons, which in turn affects some specific neural circuits related to motor control and coordinated movements. Pain The etiology of pain is complex and is mainly due to abnormal excitation of the sensory afferent and integrative functions of the nervous system for a variety of reasons, resulting in a clinical experience of discomfort and a series of subsequent functional abnormalities. Psychosomatic disorders Depression, obsessive-compulsive disorder mainly psychosomatic disorders are the highest level and most complex neural network dysfunction syndrome, the main cause of which is the alteration of the overall excitability of the neural network, abnormal execution of brain functions, and a series of lasting abnormalities in cognition, emotion, will, action behavior, and mental activity.