The brain is one of the most delicate and complex objects in the universe, so tinkering with its activity may seem like a fool’s errand. Yet armed with a growing understanding of the way we process perceptions and memories, neuroscientists are starting to build implants they hope can treat a range of disorders – from blindness to paralysis. But how do these implants work, and what’s possible? Here’s our potted guide to the amazing world of creating brain implants.
Step 1: Choose a route
Certain implants, which offer deep brain stimulation, are already treating conditions like Parkinson’s disease. The ultimate aim is to communicate with the brain using sophisticated signalling, which should allow you to cure a range of other disorders. One type of implant attempts to fix a problem right at the start of a sensory experience like sight or hearing. Retinal implants may be able replace faulty eyes, for instance, while cochlear implants help to restore hearing to the deaf, so far with some success. A second type of device could transmit signals from the brain to the limbs to cure paralysis or operate robotic limbs. A third breed of implant may bridge connections within the brain itself – replacing a damaged hippocampus to store and regenerate memories.
Step 2: Crack the code
Step 3: Train it up
Step 4: Infiltrate the brain
Science Photo Library
Once you know the brain’s code, the next challenge is to transmit those signals safely, without damaging our delicate neural tissue. Electrodes cause scarring and are attacked by the immune system, but various approaches could minimise the damage. You can wrap them in silk, so they slide through the tissue, or coat them in neurotransmitters and growth hormones to encourage surrounding neurons to grow new connections. Others are looking at making the electrodes themselves from soft “hydrogels” – the material used in contact lenses.
Step 5: Let there be light
Alternatively, you could instead try to massage neurons with light rays. Nirenberg, for instance, is using a technique called “optogenetics” for her artificial retinas. That involves genetically manipulating the relevant neuron cells behind the eye, so they fire when exposed to a certain frequency of light. Her device then communicates its signals with short flashes. That reduces the risk of damaging the tissue, and it can precisely pinpoint the cells that need to be kicked into action.
Step 6: Power up
Step 7: Hack your senses?
For the foreseeable future, these devices will only be used to treat people with severe disabilities. Chips to allow people to operate robotic limbs have already shown some success in human trials, while Nirenberg hopes to test her artificial retinas on humans within the next couple of years. The US Defense Advanced Research Project Agency (Darpa), meanwhile, hopes to test devices for amnesia by 2019.
Some futurists even hope that implants could confer “super-human” powers on able-bodied people. As a taste of what might come, one journalist recently hacked his hearing aid so that he could hear the WiFi signals as he walked through London. It’s not inconceivable that someone with a cochlear implant could do the same – or even use it to eavesdrop on conversations in another room.
Realistically, it is unlikely that healthy people would undergo surgery for recreational purposes, but who knows? Restoring sight to the blind or helping the paralysed to walk were, after all, beyond our imagination only a few decades ago.