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Cochlear implants (CIs) treat sensorineural hearing loss by electrically stimulating the auditory nerve with a electrode array placed in the scala tympani, one of three fluid filled chambers of the cochlea. It won’t work, however, if the neural pathway is severed between the inner ear and brain. In these cases, the only remaining option is an auditory brainstem implant (ABI), which stimulates the brainstem at the cochlear nucleus where the auditory nerve makes its first connection.

This is not without difficulty. The CI works in large part due to the orderly tonotopic organisation of the cochlea - frequencies are represented along the length of the coiled organ, with high frequencies at the base, and low frequencies at the tip, or apex. While tonotopicity is preserved throughout the auditory system, it’s not nearly so accessible as in the cochlea. ABIs also involve neurosurgery about the brainstem, a region not to be idly meddled with, given that it also governs vital functions like arousal and respiration.

The culmination of these and other difficulties is that ABIs don’t work; at least, not to the extent that CIs permit speech perception in many individuals. This is not unlike early CI models, which were originally intended to cue lip reading. But, as the technology has matured, far better outcomes have been achieved - especially in those implanted at a very young age. This is thought to be due to a greater capacity for neural reorganisation, or plasticity; the ability to adapt to the impoverished auditory information provided by the CI. In contrast, ABIs, are largely restricted to providing environmental auditory cues, not speech perception.

So, with that rather extended introduction; The Age reports that three-year-old Jorja Steele received an auditory brainstem implant earlier this month , which is a very rare undertaking in a child. The outcome will be fascinating - one would hope that as in young CI recipients, Jorja’s brain will learn to adapt to the coarse stimuli provided by the implant, and make sense of it.

Article Links: High hopes for implant to penetrate Jorja’s silent world, Small hole opens Jorja’s mind to a sound future

(Second Photo: Penny Stephens, Jason South)

The new Jaycar catalogue for 2007 is out. Page 408, first item on the right…

USB Keychain Bible This tiny electronic bible plugs into your computer’s USB port and contains the complete Old and New Testaments in the King James Version in both English and Spanish. It also has a search function to help you find your favourite verse. A wonderful gift and keepsake.

At the bottom of the same page…

USB Pole Dancer Hit the tunes and this little lady does her thing! She launches into her routine anytime she hears music playing along with an LED coloured light show to complete the effect. Powered from any USB port, the unit has built in amplified speaker with built in volume control. She also has a 30 second demo track so you’ll never be without a bit of pole action.

Either or both can be yours for under fifty bucks (USB Bible, USB Stripper, Scan of Catalogue Page).

Over the years I’ve designed quite a few circuit boards, and accompanying schematics, using Protel, or more lately, EagleCAD. The former is exceedingly expensive and bloated. The free version of the latter is more affordable but limited in board size and layer number.

In the last few weeks, I’ve ditched both and moved to a free (GPL licensed) package called KICAD. Developed by French academic Jean-Pierre Charras, originally as an exercise in learning C++, it includes integrated schematic layout, PCB design, and a Gerber viewer. Very quick, stable, and easy to use. And it runs on both Linux and Windows, which has proven very handy indeed. Unlike Eagle, KICAD keeps schematic symbols and PCB footprints separate until you associate them in the netlist manager, which I find to be a far more flexible arrangement. And while the part libraries aren’t as extensive as in Protel or Eagle, the library editor makes creating new parts very straight forward. There are also some utilities available for converting schematic symbols and footprints from Eagle to KICAD format. It’s an outstanding little package! A tutorial for getting started is available here.