Visualize a computer chip for a moment… it’s a “flat”, 2-dimensional piece of electronics that does some fancy electron dance somewhere within the green-toned plastic. Now, visualize what a neurological computer chip might look like… how about we start with the same flat, green-toned plastic electrical processing unit and toss on a bunch of living neural cells scrambled all over the surface.
This sort of technological device–which is not entirely science fiction–is this idea of a two-dimensional, cultured neuron network interfaced with a microfabricated electrical circuit. This system in no way resembles the network structuring seen in the human brain, so the first immediate question would be to ask why would this living, 2-D neuron network successfully electrically interface with the brain?
Well, that is a good question… but this 2-D world was (and still is) a reasonable starting point for developing the technology. In fact, because the 2-D world is still an important system for developing merged devices composed of electrical circuits and living networked neurons, developing an understanding of the fundamental neuron network function–in two dimensions–is still critical and valuable for neurotechnological research.
But, the brain is still in three dimensions, so advancing the technology to grow cultured neuron networks in controlled ways in 3-D is quite exciting. With a current published article inNature Methods, researchers from the University of California Berkeley and Lawrence Berkeley National Lab have begun some initial work on controlling the cultured growth of neurons in three dimensions along the bumps of blobs of colloidal crystals.
Micron-sized colloidal particles (i.e., really tiny balls made of clear plastic) are interesting for patterning neuron networks, because there has been a great deal of work on learning how to manipulate these objects using focused laser light called optical tweezers. If the wavelength of the laser beam is selected appropriately, then the living neurons will not absorb the wavelength and heat up and die. So, additional modifications to the underlying colloidal matrix could be made to the system while the neurons were growing and interconnecting along the 3-D lattice.
“Colloidal crystals make better neural networks” :: Ars Technica :: July 28, 2008 :: [ READ ]
“Colloid-guided assembly of oriented 3D neuronal networks” :: Nature Methods :: published online July 20, 2008 :: (doi:10.1038/nmeth.1236) [ READ ABSTRACT ]