Grow your own brain circuit

Leeches and zebrafish have created quite a buzz among scientists. Researchers have shown that electrodes can be grown inside the animals' nervous systems — experiments that may one day help treat people with epilepsy or Alzheimer's.

Deep brain stimulation is a procedure used for treating these neurological ailments. The procedure is complicated, invasive and risky, which explains why only less than two lakh patients worldwide have undertaken it.

Doctors cut through the skull to implant electrodes in the relevant sections of the brain, and then control the electrical impulses to the brain, overcoming the circuitry dysfunction which causes the ailment.

Now imagine if, instead of having to cut open the brain box to implant those devices, electrodes could be grown within the body. Researchers in Sweden have done that with zebrafish and leeches, by just injecting a gel.

"In recent years, there has been a shift in thinking. Instead of creating electronics that mimic biological processes, researchers are saying, why not let biology do the work instead, and create such sets of electronics," says Xenofon Strakosas, 38, a bioelectronics researcher at Linkoping University, Sweden, and one of the lead authors of the research paper on the subject, published in February in the journal Science (bit.ly/bioelectronics-science).

As the material for the electrodes has to be soft, the scientists created a gel using organic molecules and blended them with enzymes. "When this gel is injected into a living tissue, the biology of the tissue takes over and makes the gel electrically conductive," he explains.

The researchers initially used zebrafish as the animal model to prove the biocompatibility of their electrodes and later replicated the experiments on the nervous system of leeches. Leeches have a relatively simple nervous system and are ideal for such experiments. The bioelectrodes, says Strakosas, can grow so near the neurons that they can over time form a mesh.

Swedish researchers have led in the sphere of organic electronics. Some years ago, another research group had created electronic circuitry in plants. However, a plant's cell wall is rigid compared to that of animal cells. So, the requirements for creating electronic circuitry in animal cells were different. "We took off our research from that point," he says, adding that the latest results have stirred up the scientific community.

The team is now working on increasing the life cycle of the gel. They also intend to work with mammals.

The new generation of bioelectrodes may reimagine medical treatment. This approach does not need any genetic modification in the tissues. It would also eliminate the need for risky, invasive surgeries.