Brain implants, often referred to as
neural implants, are technological devices that connect directly to a biological subject's
brain – usually placed on the surface of the brain, or attached to the
brain's
cortex. A common purpose of modern brain implants and the focus of much current research is establishing a
biomedical prosthesis circumventing areas in the brain that have become dysfunctional after a
stroke or other
head injuries. This includes
sensory substitution, e.g., in
vision. Other brain implants are used in animal experiments simply to record brain activity for scientific reasons. Some brain implants involve creating interfaces between
neural systems and
computer chips. This work is part of a wider research field called
brain-computer interfaces. (Brain-computer interface research also includes technology such as
EEG arrays that allow interface between mind and machine but do not require direct implantation of a device.)