“The goal is to improve the quality of life for somebody who has had a severe memory deficit. If I can give them the ability to form new long term memories for half the conditions that most people live in, I’ll be happy as hell, and so will be most patients.” – Theodore Berger (Inventor of the Memory Implants)
Fig. 1: Image Representing a Typical Brain Implant
The field of biomedical engineering has risen to a new level in the past few decades. It combines various fields of engineering to ultimately design and develop artificial body parts which can duplicate its biological counterpart. It absorbs principles from different disciplines including biotechnology, medicine, mechanical engineering, electronics, computer science, etc. and applies it on the biological machine that is our body. Prosthetic limbs, artificial hearts and kidneys, artificial image processing retinas, 3D printed heart valves, synthetic tissues and stem cells are some of the wonders of biomedical engineering which help repair unrepairable damages.
The human brain is by far the most complex organ present in the human body, more complex than any supercomputer or microprocessor man has ever made. It consists of millions of neurons inter connected to each other hidden in folds of grey matter producing tiny electric signals (in micro volts) to every data which the brain processes. From the simple choice you make for breakfast in the morning to the complex cosmological problems, we call upon the unprecedented power of the brain to generate emotions and thoughts and to store them as memories. It is the epitome of the central nervous system of the human body. But, as we age the brain function tends to decrease causing memory loss or even more serious diseases such as Alzheimer’s disease and dementia. Biomedical engineer at the University of South California, Theodore Berger hopes to restore this problem by his artificial silicon chips which create memories and help recall them for more than a minute. To know how it functions we must first understand how memory works.
How does Memory Work?
One of the most important function of the brain is its ability to store data (memory). Therefore once we understand how the brain works to store and recall memory, we can begin to learn to improve our memory.Previously, researchers believed a single part of the brain to coordinate the basic functions of memory. Recent studies have found memory to be much more complex than it was believed to be. The functions of creating, storing and recalling memories consists of the synchronized action of various groups of systems of the brain. It is a web of intricately connected events which lead to the formation of memories.
· Let us consider an example of you falling in love, your eyes send visual data via the optical nerve to your brain like her physical features, color of her eyes and hair, your nose sends data of how the scent of her perfume smells like, your auditory senses send data of the sound of her voice and the way she laughs.
· This data is sent to the part of the brain which is called the hippocampus which along with the frontal cortex (front brain) decide whether a sense is worth remembering or not.
· After approval of which is stored in the long term memory by a process of firing electrical pulses between synapses (connection between the roots of neurons) causing the release of chemical carriers called Neurotransmitters (ex: a neurotransmitter called ‘dopamine’ is released which triggers the emotion of happiness) which gives a memory its own signature of stimulus.
· These can occur in a trillion ways which allows flexibility and rewiring of the neuronal circuits. This process is the memory encoding.
· While retrieving a memory the signature electric pulse pattern is re-fired to release the similar neurotransmitters. It depends on how good you register and retain the memory. One or both of the above (registry and retention) may fail when you tend to ‘forget’.
· Applying this to the same example taken in the first case, suppose that you cannot recall the date of your anniversary. The possible failures are, your brain did not value the data to be important avoiding registry, or you might not have given much attention to the date leading to the failure of retention, or simply the failure to retrieve information due to mismatch between the chemical triggers of retrieving the information and the encoded memory.
· So then what hampers memory loss during old age? Research has found that this is accounted for the decay of brain cells in the hippocampus region at the rate of 5% every decade decreasing the neurotransmitter ‘Acetylcholine’ while promotes learning and memory.
· Even neuronal diseases such as Alzheimer’s, strokes, injuries or in fact anything which disrupts the neuronal network can inhabit the formation of new memories.
Fig. 2: Image Showing Various Parts of Human Brain
But why should we let age and disabilities diminish our ability to cherish thebeauty life? Would you be willing to forget how you felt during your first love, graduation day, your wedding day, your child’s birth, your first promotion, retirement day or even simple things you need to remember to carry out everyday tasks like the way to your house orwhere you left your keys?
The Memory Chips
The Memory ‘Chips’
Note that the controlling factor of memory is the controlled firing of electrical pulses at the synapses which trigger the release of the chemical neurotransmitters. So if microcontrollers or microprocessors could be used to mimic the electronic pulse generation of the neurons, memory creation can be achieved artificially. Although it sounds doable the human brain consists of a 100 trillion synapses which fire in a signature pattern different from all other patterns, so to find a particular response would be much like finding a needle in a forest. Such complication goes into the invention of the silicon chips by Theodore Berger (no wonder it took him 35 years to study the behavior of the neurons in the hippocampus). Although human tests of neural prosthesis are yet to be conducted, Theodore and his team have reported successful reports of being able to create memories by his implants in rats and monkeys connected externally to their brains via electrodes. The primary purpose of the memory implant is to create memories.
The difficulties faced in this problem are:
1. Filtering out the brain activity to study only memory related processes so as to mimic not the entire function of the brain but a fraction of it.
2. Next, the conversion of the physical principles into mathematical equations (mathematical modelling) and applying this model to a device.
3. This device must be compatible to the environment inside the cranium of not only one brain but brains of different people.
So how exactly do neuroscientists track the brain activity? They do this by monitoring the “action potentials” (microvolt changes in the electrical activity) on the surface of neurons. They monitor these responses with respect to an external stimulus. While studying the brain, it is inadequate to concentrate only on the neuron undergoing the change, but also the effect it has on the neighboring neurons. Berger and his colleague Vasilis Marmarelis, studied these signals from the hippocampal slices from the brains of rats. After, obtaining the patterns of signals, they modelled it into a mathematical form of transformation programming it onto a computer chip. Next they researched whether they could bypass the generally received signals to an externally placed chip through electrodes and send back the processed signal back to the brain in the damaged hippocampal region through a central pathway (back again through electrodes).
Fig. 3: Representational Image Showing Working of Brain Chip
Experimental Results: Theodore and his team after applying pre-evaluative tests on live rats moved to monkeys. They attached electrodes to a monkey’s brain and connected the external chip which recorded an image which was showed to the monkey on full brain functionality. Later they doped the monkey with cocaine which in the calculated amounts inhabits that part of the brain and studied the image identification capability of the primate. Results concluded the increased performance of such memory based activities.
Berger is hopeful of moving into human trials by moving into talks with clinicians in his university who are hoping to cure certain patients with severe epilepsy by attaching electrodes on either side the hippocampus. He hopes to use this opportunity to encode memories on these trials. This will open gates to a new era of where science can be used to cure the unrepairable neuronal diseases. This concept of Berger’s would sound to a regular person like a scene taken straight out of a science fiction film. But, recent successes of electronic implants in humans include the success of ‘cochlear implants’ which help deaf people by converting sound to electrical signals which is collected by the auditory nerve. Also, prosthetic limbs (robotic) controlled by thoughts have cured cases of paralysis. So why not allow new developments to help improve the quality of life of numerous lives?