Implanted electrode grids are used to record brain activity in people who need neurosurgery – a technique known as electrocorticography.
But rather than just ‘reading’ from the brain, neuroscientists are starting to use them to ‘write’ to the brain, to the point of being able to temporarily simulate specific brain disorders for experimental studies.
This is the subject of my latest Observer column which looks at the history of open-brain stimulation studies and covers recent research by a joint British – Japanese team which has been using the grids to temporarily simulate a form of brain disorder called ‘semantic dementia’ in live volunteers.
The precision is such that the Lambon Ralph team and a team at Kyoto University Medical School, led by Riki Matsumoto, have used an implanted grid to temporarily simulate characteristics of a brain disease called semantic dementia. Like Alzheimer’s, semantic dementia is a degenerative disorder, but one in which brain cells that specifically support our understanding of meaning rapidly decline. Studies of patients with semantic dementia have taught us a great deal about how memory is organised in the brain but the disorder is swift and unpredictable, and a method that can mimic the effects while recording directly from the cortex is a powerful tool.
To be clear, the grids are not installed for this purpose. They’re installed because they are part of brain surgery to treat otherwise untreatable epilepsy. The grids allow neurosurgeons to locate the exact bit of the brain that triggers seizures so it can be removed.
The article is in part a coverage of the amazing neuroscience, from 1886 to the present day, and in part a tribute to the neurosurgery patients who have volunteered to help us understand the brain.