Britain's Nuffield Council on Bioethics, which examines ethical issues raised by new developments in biology and medicine, launched a consultation on Thursday on the ethics of new technologies and devices that intervene in the human brain.
The three main areas of the group's focus are brain-computer interfaces, neurostimulation and neural stem cell therapy.
Here are some details about each area of research and how it is being explored.
* Brain computer interfaces (BCIs)
BCIs measure and analyze a person's brain signals and convert them into an output such as movement.
A paralyzed person, for example, could use a BCI to operate a wheelchair, or someone who has extreme difficulty speaking could use a BCI to communicate via a computer voice.
These sorts of applications have been shown to be successful in a few reported cases, but the technology has not yet been developed for regular clinical use and there are questions over whether these technologies are reliable enough for use in everyday life.
Military applications, such as remote control of vehicles and machinery are not yet in wide use but are being researched and tested, mainly in the United States.
Some commercial BCI developments are already on the market in the gaming sector. Gamers can buy a wireless headset that aims to replace a joystick by controlling game play through brain signals.
The use of BCIs sometimes require surgery to implant electrodes into a person's brain, although the most successful current developments are less invasive ones That detect brain signals from the scalp.
Different regions of the brain are known to be linked to areas of perception, such as pain, sound or vision. Neurostimulation involves applying an electric or magnetic stimulus to nerves to alter brain activity in a specific area.
The two best-known types are transcranial magnetic stimulation (TMS), which is usually applied through a hand-held or chair-bound device and is non-invasive, and deep brain stimulation (DBS) which requires brain surgery to place an electrode in the brain and wires under the skin.
TMS is already in clinical use, mainly to treat severe depression, and research is under way on possible uses for other conditions such as obsessive compulsive disorder (OCD), Alzheimer's disease, and pain disorders such as migraine.
TMS has also been shown to have potential for improving memory and sharpening focus for learning, so research is under way on non-medical enhancement uses such as in education or military training.
DBS is already used in treatment of Parkinson's disease, OCD and movement disorders such as dystonia, which causes tremors. Research is under way on possible benefits for patients with other disorders such as epilepsy, stroke, Tourette's syndrome, severe pain and depression.
* Neural stem cell therapy
Researchers are developing neural stem cells that could be used in treating conditions that involve the loss of nerve cells in the brain, for example in Alzheimer's disease, stroke or Huntingdon's disease. The stem cells are injected into the brain under general anaesthetic.
There is considerable interest and investment in this area of research, both privately and publicly. Small scale preliminary human trials are under way but the treatment is not yet routinely available.
Neural stem cell therapies are less well understood than other types of brain surgery and there are some concerns associated with its use - for example the risk of tumors forming in the brain and the possibility of unwanted changes being introduced into the brain which could alter mood, behavior and ability.
SOURCE: Nuffield Council on Bioethics