Eventually they hope the cells could also be used to provide healthy tissue that can be implanted into patients to treat neurodegenerative diseases and brain damage.

Dr Rick Livesey, who led the research at the University of Cambridge's Gurdon [corr] Institute, said: “The cerebral cortex makes up 75% of the human brain, is where all the important processes that make us human take place. It is, however, also the major place where disease can occur.

“We have been able to take reprogrammed skin cells so they develop into brain stem cells and then essentially replay brain development in the laboratory.

“We can study brain development and what goes wrong when it is affected by disease in a way we haven't been able to before. We see it as a major breakthrough in what will now be possible.”

The cerebral cortex is the part of the brain that is responsible for most of the major high-level thought processes such as memory, language and consciousness.

While human brain cells have been created from stem cells before, this has relied upon embryonic stem cells. Attempts to make them from skin cells have produced neurons that are not found in the cerebral cortex.

Dr Livesey and his colleagues were able to create the two major types of neuron that form the cerebral cortex from reprogrammed skin cells and show that they were identical to those created from the more controversial embryonic stem cells.

Dr Livesey, whose findings are published in the journal Nature Neuroscience, said this may eventually lead to new treatments for patients where damaged tissue could be replaced by brain cells grown in the laboratory from a sample of their skin.

He said: “You don't need to rebuild damage to recover function as the brain is quite good at recovering itself – it does this after stroke for example. However, it may be possible to give it some extra real estate that it can use to do this.

“We can make large numbers of cerebral cortex neurons by taking a sample of skin from anybody, so in principal it should be possible to put these back into the patients.”

Dr Simon Ridley, head of research at Alzheimer's Research UK, which funded the study alongside the Wellcome Trust, added: “Turning stem cells into networks of fully functional nerve cells in the lab holds great promise for unravelling complex brain diseases such as Alzheimer's.”

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