Original URL: http://www.theregister.co.uk/2008/12/16/iedm_chip_to_cell_communication/

Chip boffins hone silicon-brain interface

First slugs. Then humans

By Rik Myslewski

Posted in Science, 16th December 2008 07:03 GMT

IEDM The International Electron Device Meeting (IEDM) opened today in San Francisco, the annual IEEE-sponsored gathering of the world's top 1,500 semiconductor engineers. From the opening session, it was clear there's a lot going on in their fertile minds - including plans to get devices inside your mind. Literally.

The first talk in this morning's opening Plenary Session was "Electronic and Ionic Devices: Semiconductor Chips with Brain Tissue." Yes, you read that correctly: brain tissue. For half an hour, Peter Fromherz of Munich's Max Planck Institute for Biochemistry held a tough crowd's close attention as he described his work on silicon-to-neuron interfaces.

According to Fromherz, although the research he and his team are undertaking to create interfaces between ionic devices such as nerve cells and electronic devices such as chips is still in its early stages, its history dates back to 1783, when Luigi Galvani (as many of us were taught back in high school) first made a frog's amputated leg twitch by touching it with a spark.

Things have gotten quite a bit more sophisticated in the intervening 225 years - including, for example, in-brain electrical stimulation of Parkinson's disease patients - but a safe, stable, reliable, and rugged brain/chip interface remains elusive.

The brain is an interconnected morass of neurons. Any comprehensive electronic interface with it would need not only to have physical contact with, as Fromherz said, "hundreds of thousands or millions of contact sites." But those sites would have to be stable both in placement and biochemical interaction. You don't want them firing up the wrong neurons, poking them destructively, or chemically interacting with them in nasty ways, do you?

Fromherz cited three main directions for hybrid-neuroelectronics research: neurosensorics, neuroprosthetics, and neurocomputing. The first investigates devices that could study the brain, the second focuses on creating devices that could replace or supplement organic functions such as sight and hearing, and the third explores using brain tissue to inform computing design and function.

As you might imagine, that third area - neurocomputing - is the furthest away, seeing as how tissue/chip interface development is still in its infancy. You can forget about organic computers floating in Mason jars for the time being.

Fromherz went on to describe in detail his team's early work on the cell/chip interface. Interestingly, the neurons that they used for testing weren't from humans - which, for some reason, The Reg finds a wee bit of a relief - but from slugs. It seems that slug neurons are quite large and thus easier to work with than mammalian neurons.

Silicon-Slug Talk

In 1991, Fromhertz and company managed to get a simple electronic/ionic dialog going on between a silicon capacitor and a slug neuron - and when we say simple, we mean very, very simple: An electron-carrying signal was sent from a silicon-based capacitor, through an electrolyte, and across a 5nm cell membrane where it induced an ionic channel in the membrane that caused a replication of the pulse of the trigger signal from the chip.

If that last sentence confused you, don't fret - it's both a complex concept to explain and a gross oversimplification of the methods used. The basic take-away: The chip could talk to the cell, and vice-versa. Not that they could say much. But, hey, you have to crawl before you can walk, right?

Importantly, Fromherz's chip/cell communication could be conducted with no corrosive nor electrochemical damage to either the chip or the cell. However, that slug-neuron success was the only giant step in the development of a chip/cell interface for 17 years. It was only earlier this year that the team managed to pull off essentially the same feat with much smaller and far more delicate mammalian neurons, in this case taken and cultured from those great sacrificers for humanity: lab rats.

Back in 1991, the idea of electronics being able to cause brain-cell activity was unsettling to some observers. Fromherz, in fact, read to the assemble engineers a worried comment from one observer from that time: Now that "a functioning neuro-net can be physically attached to a silicon chip," the observer said, we should explore the "philosophical and spiritual consequences." Fromherz brushed aside such concerns, and the audience chuckled in agreement.

Don't be surprised, though, that when this type of brain/electronic interface becomes more controllable, interconnectable, and manageable - and it most surely will - such concerns will be debated. There will, of course, be those who argue strictly from a religious perspective that there are places that science shouldn't go - the Catholic Pope, for example, recently restated his objection to both stem-cell research and in-vitro fertilization. And there will also be those who fear that electronic control over neurological processes will lead us down a slippery slope towards The Borg.

But there are great benefits to be obtained from chip/cell interactions as well. At tomorrow's IEDM, for example, two papers will be presented that will detail recent neuroprosthetic research.

The first, "Systems Design of a High-Resolution Retinal Prosthesis" by J. Weitland and his crew from the University of Southern California, will explain how they have managed to fit 1000 light-sensing electrodes to be installed in a tiny in-eye device, coupled with an advanced image-processing technology, and powered remotely. Their goal: greatly improved artificial sight for the vision-impaired.

The second, "Microelectronics Meets the Brain: Towards Implantable Neural Communications Interfaces" by Y.-K. Song and his cohorts at Brown University, will discuss "thought-to-action telemetry." At the core of their work is an active sensor that's surgically implantable with one element below the skull and that interfaces with the brain, and another above the skull but below the skin that's able to communicate with telemetric devices. The entire system, according to the paper's authors, will be safe and highly reliable.

Artificial limbs haven't made us The Borg. Neither will artificial sight nor thought-to-action telementry.

And those who oppose such advances will be assimilated. ®