102 Human Body Version 2.0 Researchers  at  MIT  and  Harvard  are  developing  neural implants  to  replace  damaged  retinas.  [4]  There  are  brain implants for Parkinson’s patients that communicate directly with  the  ventral  posterior  nucleus  and  subthalmic  nucleus regions of the brain to reverse the most devastating symptoms of this disease. An implant for people with cerebral palsy and multiple sclerosis communicates with the ventral lateral thala- mus and has been effective in controlling tremors. “Rather than treat the brain like soup, adding chemicals that enhance or suppress certain neurotransmitters,” says Rick Trosch, an American physician helping to pioneer these therapies, “we’re now treating it like circuitry.” A  variety  of  techniques  are  being  developed  to  provide the  communications  bridge  between  the  wet  analog  world of biological information processing and digital electronics. Researchers at Germany’s Max Planck Institute have devel- oped noninvasive devices that can communicate with neurons in both directions. [5] They demonstrated their ‘neuron tran- sistor’ by controlling the movements of a living leech from a  personal  computer.  Similar  technology  has  been  used  to reconnect leech neurons and to coax them to perform simple logical  and  arithmetic  problems.  Scientists  are  now  experi- menting with a new design called ‘quantum dots’, which uses tiny crystals of semiconductor material to connect electronic devices with neurons. [6] These developments provide the promise of reconnecting broken neural pathways for people with nerve damage and spinal cord injuries. It has long been thought that recreat- ing these pathways would only be feasible for recently injured patients  because  nerves  gradually  deteriorate  when  unused. A recent discovery, however, shows the feasibility of a neu- roprosthetic  system  for  patients  with  long-standing  spinal cord injuries. Researchers at the University of Utah asked a group of long-term quadriplegic patients to move their limbs