PLASTIC BRAIN

 Plastic Brain

Cameron Mott used to have seizures, a condition called Rasmussen’s Encephalitis. Suddenly, she would drop to the floor. To be prepared for this uncertain eventuality she had to wear a helmet all the time. And one day she would be paralysed and be dead. 

Therefore, she was operated on and one half of her brain was removed. Her post operative brain scan, with a blank hemisphere, looked scary. But she survived. Not only that, she lived normally too. She understood language, did maths, participated in sports and enjoyed music. The remaining half of her brain re-wired to take over the functions of the missing part. Literally, all neural functions had been crammed into one half of her brain.

Michael Chorost is a cochlear implant recipient. The implant receives sound waves and converts them into electrical impulses with the help of 16 tiny electrodes, feeding them to undamaged auditory nerves. The latter then transmits the signals to the auditory cortex which decodes them for our brain to ‘hear’. But, after the implant, the first sentence Michael heard was, “Zzzzzz szz szvizzz ur brfzzzzzz?”. However, after a few months, he would hear an intelligible “What did you have for breakfast?”, if addressed with the same question again.

David Eagleman, in his book The Brain, calls the brain ‘a general purpose computing device’. Whatever sensory input you feed it, it figures out how to make sense of it. It live-wires in real-time. Similar to the cochlear implant, the retinal implant, meant for blind people, replaces the photoreceptors of the eye, sending different types of visual signals to the optic nerve. And the latter adapts and the blind 'sees'. So plastic is the brain!

We have sensors for hearing, touch, sight, smell, taste, temperature, vibration, balance, etc. But add a new sensor and the brain will interpret it too. Take out a heat sensor from a snake, an electrosensor from a glass knifefish, and magnetite from birds and cows and you will see heat signatures, and read EMF, and orient yourself with the Earth’s magnetic field. You will echolocate like bats, or hear from long distances like elephants, or smell unique body odour like dogs, if you plug in their sensors. Our brain is quite an adaptive plug-and-play device.

There are flip-goggles that will invert your vision or turn your left side into right side and vice versa. Initially, you will go mad, you won’t be able to grip and hold, you will slip and fall. Gradually, you will be able to cook and even ride a bicycle wearing such goggles.

In successful experiments, visual feed has been converted into tactical images fed to the lower back or the forehead, or as aural images to the ear, or as tiny electric shocks to the tongue and the recipient has been able to ‘see’! BrainPort is one such device that feeds such pulses to the tongue of blind subjects (it would otherwise feel like carbonated fizz). Erik Weihenmayer is a blind athlete who uses the BrainPort to rock climb. 

Similarly, the VEST or Variable Extra-Sensory Transducer, which is worn under clothing, has been built by David Eagleman that gives hearing to the deaf by feeding patterned vibrations to the torso. It would take five days for the brain of a so-called deaf person to make sense of spoken words, and after several months, start hearing ‘normally’.

If a deaf person wears the VEST for the first time, and I say, “Hello!”, his brain won't have any sense of the moving pattern of vibrations over his body representing ‘hello’. But as the torso ‘hears’ more and more overlapping patterns of vibrations, the brain learns to assign meanings, catalogue the sounds and eventually have its inventory of vibrations for every alphabet, syllable and consonant.

In the words of Eagleman, “The brain doesn’t care how it gets the information, as long as it gets.”