A future, when memory loss can be reversed by neuronal prosthetic implants, not too far

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A man-made device that can reverse memory loss… Sounds too good to be true? Well read on, to know just how scientists and researchers are gearing up for a future when human memory capacity can be dramatically improved by means of artificial memory prosthetics.

Human Memory Prosthetics_2Neuroprosthetics is a field of medical science, involving the principles of both biomedical engineering and neuroscience, that aims at developing complex neural prostheses, needed to reinstate normal neuronal activity in patients after accidents and injuries. Neuro prostheses is actually a series of specialized devices that can imitate and also replace the motor, cognitive and sensory processes, especially in case of impaired neural system. Examples include Cochlear implants that play an important role in the treatment of auditory disorders.

One of the major projects in this discipline, ongoing since the early 1990s, is the development of memory prosthetic devices that attempt to mimic the complex neurological activities of the brain, with regards to the creation of long-term memories. These researchers are working towards a day when normal brain function can be restored to full capacity, by means of  artificial neural implants, in patients with severe memory loss.

Human Memory Prosthetics_4Theodore Berger is credited with the development of the first memory prosthetics, in rats 

Theodore Berger, a biomedical engineer and neuroscientist at the University of Southern California, is probably one of the first persons to dabble with synthetic memory enhancement chips. For 35 years, he and his colleagues have been studying the different aspects of the hippocampus, a seahorse-shaped structure in the brain that is responsible for the formation and processing of short-term and long-term memories in humans and other vertebrates. A vital part of Berger’s project, accomplished with Valisilis Marmarelis of USC as the partner, included the analysis of the various activities taking place in the hippocampus, followed by the development of accurate mathematical theorems and equations that would enable them to replicate and integrate these mechanisms into a silicon microchip.

A prime breakthrough in the project came in 2011 when Wake Forest University scientist Samuel Deadwyler, in collaboration with  Theodore Berger, finally managed to create the very first memory prosthetic device, that indeed proved to be successful in improving memory retention capacity in rats. The resultant device was in the form of a  microchip implant, consisting of 32 electrodes run with the help of a complicated algorithm that could in turn decode and reproduce the neural signals sent from one end of the hippocampus to the other.

Human Memory Prosthetics_6The study involved rats as the subjects and a task that required them to push a particular lever placed before them and then after some time, press a different lever, based on their memory of the earlier round. In order to identify and record the specific nature of the electrical processes occurring, when the rats were busy completing the task, in the right and the left parts of the hippocampus, two sets of multi-electrode array were placed in the respective regions of the brain. While one set managed to decipher the activities taking place in the CA3 layer of the hippocampus, the other captured the neural signals in the area called the CA1 layer, both of which co-function in the brain to naturally create long-term memories.

Consequently, the scientists were able to produce an artificial hippocampus, that could not only read the information collected by the electrodes and replicate the CA3-CA1 interactions, but also repeat them when prompted to do so. Implanting it inside the brains of the rats resulted in a dramatic amelioration of their capability to locate and press the correct lever as well as in the normal memory potential of the rats. Since then, the device has been successfully tested in non-human primates, such as monkeys. By implanting it into drugged monkeys, with impaired brain function, scientists have been able to better their memory retention power.

Human Memory Prosthetics_7Fast forward to 2014 and the U.S. Defense Advanced Research Projects Agency(DARPA) has commissioned two separate groups of researchers to develop a similar neuronal prosthetic implant, within the next four years, that can be used to treat severe memory loss in human patients. The project will be part of DARPA’s Restoring Active Memory(RAM) program, aimed to help reinstate normal memory activity in case of the 270,000 U.S. war veterans who have suffered some kind of brain injury, since 2000. If successful, the program will indeed be immensely beneficial for patients with schizophrenia, amnesia, dementia and other brain disorders.

One team, led by Michael Kahana at the University of Pennsylvania’s Computational Memory Lab, will concentrate on the processes involved in memory formation and retrieval. Talking about the project which will quite possibly aid in the recovery of Parkinson’s and epileptic patients, Kahana said:

The memory is like a search engine…In the initial memory encoding, each event has to be tagged. Then in retrieval, you need to be able to search effectively using those tags.

With epilepsy patients who have already been hospitalized, and implanted with micro-electrodes to examine the nature of their seizures, as the primary test subjects, the researchers will proceed by detecting and analyzing the various neuronal activities in the brains of the patients. Minneapolis-based medical equipment manufacturer Medtronic has  devised a highly specialized “closed-loop” artificial implant that can register these neural signals and then use the information accumulated to trigger the brain into repeating the particular activity. However the production of such a device poses a crucial problem, in that it requires an extremely complex and intricate circuitry that can record and process the signals at lightning speed. Kahana elaborates:

We need to take analyses that used to occupy a personal computer for several hours and boil them down to a 10-millisecond algorithm.

The other group, headed by neurophysiologist Itzhak Fried of the University of California in Los Angeles, will take a slightly different route. The area of interest of these researchers is the entorhinal cortex(EC) present between the hippocampus and the neocortex, and dealing primarily with memory production and consolidation. Stimulating this area of the brain has previously shown to improve the test taker’s response to memory tasks.

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In association with California-based Lawrence Livermore National Laboratory, Fried and his team has developed a functional closed-loop memory implants, by first printing the tiny electrodes onto a polymer attached to a silicon wafer. The polymer is then removed and then shaped into pliable cylinders measuring 1 millimeter in diameter. One fully-functional implant system will contain 2 of these polymer plates, each comprising of 64 microelectrodes, which are in turn capable of registering the electrical activities of neurons and then replicating them. Fried says:

Our approach to the RAM program is homing in on this circuit, which is really the golden circuit of memory.

Although still at its embryonic stage, the project has already opened up a whole range of possibilities with regards to the treatment of various kinds of neurodegenerative disorders. Reactions in the medical world, towards the development of memory enhancing prosthetics, have indeed been extremely enthusiastic. According to Charles Wilson, a neuroscientist at Los Angeles’s University of California:

It’s an exciting demonstration of the capabilities that we have now, not of only reading neuronal activity of the brain but also manipulating it… Hopefully, this could be clinically useful in the future.

Talking about the significance of this project in the field of psychiatry and other forms of mental illness, Steven Hyman, head of the psychiatric research department at MIT and Harvard, says:

The kind of hardware that DARPA is interested in developing would be an extraordinary advance for the whole field…I think that approaches that involve devices and neuromodulation have greater near-term promise.

Image credits: Lawrence Livermore National Laboratory

Via: IEEE Spectrum / Wikipedia / MIT Technology Review

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