AFTER buttoning up a lab coat, snapping on surgical gloves and spraying them with alcohol, I am deemed sanitary enough to view a robot’s control system up close. Without such precautions, any fungal spores on my skin could infect it. “We’ve had that happen. They just stop working and die off,” says Mark Hammond, the system’s creator.
This is no ordinary robot control system - a plain old microchip connected to a circuit board. Instead, the controller nestles inside a small pot containing a pink broth of nutrients and antibiotics. Inside that pot, some 300,000 rat neurons have made - and continue to make - connections with each other.
As they do so, the disembodied neurons are communicating, sending electrical signals to one another just as they do in a living creature. We know this because the network of neurons is connected at the base of the pot to 80 electrodes, and the voltages sparked by the neurons are displayed on a computer screen.
It’s these spontaneous electrical patterns that researchers at the University of Reading in the UK want to harness to control a robot. If they can do so reliably, by stimulating the neurons with signals from sensors on the robot and using the neurons’ response to get the robots to respond, they hope to gain insights into how brains function. Such insights might help in the treatment of conditions like Alzheimer’s, Parkinson’s disease and epilepsy.
“We’re trying to understand what is going on inside this brain material that could have direct implications for human health,” says Kevin Warwick, Reading’s head of cybernetics, who is running the project with Hammond and Ben Whalley, both neuroscientists.
The team are far from alone in this aim. At a July conference on in-vitro recording technology in Reutlingen, Germany, teams from around the world presented projects on culturing brain material and plugging it into simulations and robots, or “animats” as they are known.
To create the “brain”, the neural cortex from a rat fetus is surgically removed and disassociating enzymes applied to it to disconnect the neurons from each other. The researchers then deposit a slim layer of these isolated neurons into a nutrient-rich medium on a bank of electrodes, where they start reconnecting. They do this by growing projections that reach out to touch the neighbouring neurons. “It’s just fascinating that they do this,” says Steve Potter of the Georgia Institute of Technology in Atlanta, who pioneered the field of neurally controlled animats. “Clearly brain cells have evolved to reconnect under almost any circumstance that doesn’t kill them.”
After about five days, patterns of electrical activity can be detected as the neurons transmit signals around what has become a very dense mesh of axons and dendrites. The neurons seem to be randomly firing, producing pulses of voltage known as action potentials. Often, though, many or all of them will fire in unison, a phenomenon known as “bursting”.
There are various views on what these bursts are. Some see them as pathological activity - akin to what happens in epilepsy - while others see them as the neural network expressing a stored memory. “I interpret them as seizure-like behaviour,” says Potter. “I think the bursting is a function of sensory deprivation.”
Like a creature with no limbs or senses, the cut-down brain is simply bursting out of boredom, says Whalley. “With no structured sensory input the hypothesis is that you get arbitrarily random and quite often detrimental activity because all these cells are asking for some kind of direction.”
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