A research group at MIT has announced that they’ve developed a chip that mimics the synapse between neurons in the human brain.
In the human brain, a synapse is the structure which enables a neuron to send information to other parts of the brain. Typically, that information is either electrical or chemical, and the signal can carried to either another neuron (which is what’s typical) or a different cell in the brain.
In the brain, the signals travelling through the synapses rely on action potential, which is the electrical energy created by the difference in concentrations of charged atoms (ions) on the inside and outside of neuron, which move back and forth through ion channels. The regulation of that flow of ions is key to the working brain.
According to MIT, this chip works similarly. It avoids the typical binary behavior of transistors, where the transistor is simply turned on or off. Instead, the transistors operate on a gradient of electrical current. This is similar to the ion flow in the actual synapses in the brain, where there’s always some charge on the interior and exterior of the neuron – it’s just the difference in potential that matters. This allows the team to mimic the behavior of ion channels in the brain.
This design definitely is a different take on a brain mimicking chip than IBM’s cognitive computer. The IBM chip uses the structure of the human brain as map for the design of the circuits in their chip. Which is necessary in order to achieve the practical minituriazation they’re looking for. To give you an idea of what I mean, look at it this way – if it takes MIT 400 transistors to mimic one synapse, then by my back of the envelope calculation it would take about 100 million processors in a typical desktop computer to mimic the number of synapses firing in a typical human brain.
That said, this is a fascinating achievement, and the chip should be invaluable to neuroscientists who want to understand more about the underlying structures in the brain and conduct experiments that wouldn’t be possible otherwise. Indeed, the MIT team plans to use this chip to model neural structures such as vision in order to gain a deeper understanding of the brain. It’ll be interesting to see what they uncover.