Controversial cyborg rat tests target brain treatments
- 8 March 2012
- From the section Technology
A rat lies motionless on a sterile, spotless table.
It is alive, but heavily sedated.
Closer inspection reveals that this is no ordinary rodent.
Electrodes are being used to stimulate its brain, creating waveform readings on a nearby computer screen.
The rat is part of a research project at Israel's Tel Aviv University psychology department.
Scientists are attempting to replace part of this and other rats' brains with digital equipment, effectively turning them into cyborgs.
Anti-vivisection campaigners have described the tests as "grotesque" but the researchers claim the work will eventually help them make repairs to what is possibly the world's most complex computer - the human brain.
The work aims to help people with diseases such as Parkinson's or those who have suffered a stroke.
It involves swapping impaired brain tissue with a microchip that is wired to the brain, allowing it to carry out the tasks that the healthy tissue would have performed.
"Imagine there's a small area in the brain that is malfunctioning, and imagine that we understand the architecture of this damaged area," says Prof Matti Mintz, a psychobiologist at Tel Aviv University who is involved in the international project.
"So we try to replicate this part of the brain with electronics."
To do it, the researchers insert sets of electrodes up to 1cm deep inside a rat's brain and then connect them to a microchip embedded just under the skin of the rodent's skull.
The chip then receives and interprets sensory information from the brainstem - the lower area of the brain - and analyses it as the original biological part would, before transmitting the information back to motor centres in the brainstem.
"For example, there's a region of the brain that controls one simple motor movement - breathing," says Prof Mintz.
"Right now, if a patient loses this area, there's no way to recover. But if we're able in the future to replace such an area that is responsible for very discrete but extremely essential movement, it will be great.
"And it is on the horizon."
To demonstrate that its idea works, the team applied the principle of classical conditioning, first demonstrated by the Russian scientist Ivan Pavlov in 1927.
He noticed that his dogs began salivating when they saw the person who fed them. So he used a bell to let them know that their meal was ready - and after just a few repetitions, he found out that the animals started to salivate when they heard the bell, even if the food was not there.
Prof Mintz's team did something similar with rats.
The researchers decided to work on an area of the brain called the cerebellum, which is responsible for controlling and timing motor movements, such as learning how to blink in response to a stimulus.
They took advantage of the fact that if a rat hears a particular sound before it gets hit with a jet of air, it will eventually blink when the sound is played ahead of the puff reaching its eyes.
"We know how to blink. Currently, I'm blinking very freely," says Prof Mintz.
"We also know how to record that the animals are learning to respond to a stimulus - we plant electrodes around the eye, and record the muscle activity to see when the rat actually closes its eye.
"And we know that when we damage the biological structure [the cerebellum] the animal cannot learn this simple motor response any more, never again, and nothing in the brain can replace this learning.
"So after having studied this brain region, we constructed a simulation that works in a similar way to the original biological system - and when we see some recovery of the lost movement, it is clear that it is coming from our synthetic device and not from any other area of the brain."
Science fiction helped the researchers come up with the idea of replicating a specific brain function with a microchip.
The genre has long been populated by cyborgs and other related creatures, from Terminator and Robocop to Isaac Asimov's bionic robots and Blade Runner's bioengineered "replicants".
Although neuroscientists have quite literally been picking at the brain for decades, it is only recently that there have been significant breakthroughs in the area.
One instance is a brain-computer interface which allows a person with disabilities to control a computer cursor through the power of thought alone. It works via electrodes attached to their brain which read specific signals.
Prosthetic limbs function through brain implants, too, but they also only work one way, receiving signals and interpreting them into physical actions.
Getting the artificial portion of the cerebellum to receive one set of signals and send out an entirely different set of commands proved especially challenging.
"The only way to for such a project to succeed is by combining different disciplines - and this is where 'nano-bio-info-cogno' comes in - uniting nanotechnology, biology, informatics and cognitive science," says Prof Mira Marcus-Kalish of Tel Aviv University, who is also taking part in the project.
"We take nanoelectrodes into a biology application, try to analyse everything through informatics, and then also use cognition."
The next step will be getting the rats to perform not just one, but several physical actions, says Prof Mintz.
"Let's imagine a person loses a big chunk of cerebellum, due to a haemorrhage, or a lesion, or due to ageing. Cerebellum ages very fast, and that's why we lose tiny motor functions," he says.
"So we need to find how to recover motor functions consistent of longer sequence of movements."
Once the trials with rats are over and successful, the researchers plan to move to human subjects.
They say they hope to help people and save lives. However, animal rights activists describe the research as "disgraceful" and "abhorrent".
"This type of research raises enormous ethical concerns, let alone the poor animals whose lives are wasted on dubious and ego-driven experiments," says Jan Creamer, chief executive of the UK-based National Anti-Vivisection Society.
"The NAVS is totally opposed to all forms of animal experimentation and advocates the use of sophisticated non-animal techniques, which this clearly is not. As an example, we are currently funding a long-term project concerned with the human brain and its functions and our research uses cutting edge technology, not the outmoded animal model."
As the researchers replace bigger parts of the brain with electronics other questions are also likely to be raised: how far the research should be taken and how many neurons can be replaced before our bodies become controlled by a machine, rather than the other way round.
Although some may argue that we already interfere with nature when we implant a pacemaker or transplant a heart, the brain is viewed differently because it is the organ that controls everything in the human body.
"It's fascinating how people get worried when it comes to their brain, there's this fear that some alien intruder will take over ourselves," says psychologist Prof Carlo Strenger from Tel Aviv University, who is not involved in the study.
"But think of the many people who have suffered brain damages because of accidents, of the people with degenerative diseases - the more replacement parts we have for our body, the more people are not just alive, but healthy.
"One philosophical question could arise once we'll be able to download a person's whole brain onto a chip and then implant the chip into someone else's body.
"This is a problem we don't yet know how to solve. But we're not there yet."