Nerve-16-17-Final.Pdf

2 the nerve • 2016-17 CONTENTS R EARCH IN BRIEF 4 - The Diffusive Memristor Gabrielle Abad 9 - Zika Virus & Its Neurological Impacts Srijesa Khasnabish A icles 11 - Excoriation Disorder Emily Yao 14 - Infrared Vision in Snakes Can Yumuk 16 - Conquer Your Mind Mehul Khetrapal 18 - Neuroeconomics Tiantian Li 22 - The Next Generation of Captain America Akane Ichiki 24 - Architecture & Cognition in the Sydney Crotts Monolingual & Bilingual Brain S UDENT R EARCH 26 - Restoring Hearing Loss Andrea Zhang O INION 27 - The Suffering Artist Amanda Fortin 32 - Neuroethics of Identity Erin Ferguson the nerve • 2016-17 3 STAFF Olivia Nguyen Erin Ferguson Colin Stuart Gabrielle Abad Janelle Maxwell Ian Anderson Ben Rabin Sydney Crotts Priyanka Shah Camila de Freitas Josh Strauss Erin Ferguson Colin Stuart Amanda Fortin Emma Wheeler Mehul Khetrapal Ryan Wong Srijesna Khasnabish Emily Yao Katherine Kolin Can Yumuk Tiantian Li Andrea Zhang Haodong Liu Sydney Crotts Martinelli Valcin Radhika Dhanak Valentina Wicki Nic Larstanna Emily Yao Natalya Shelchkova 4 the nerve • 2016-17 LETTER FROM THEE TOR Dear reader, The word ‘neuroscience’ is often intimidating to those who do not pursue the study Janelle Maxwell of the human brain in an academic setting. Yet, with neuroscience research being Ben Rabin one of the largest growing fields to date, it is paramount to make all knowledge ac- cessible without all the scientific jargon in order to propel the general understand- Priyanka Shah ing of our society forward. Having served as editor-in-chief for the Nerve Magazine Josh Strauss for two and a half years, I am continuously humbled and inspired by the passion in Colin Stuart our community to make neuroscience, psychology, biomedical, and other scientific fields more available to the public. Our team may be small, but our creativity is Emma Wheeler always surprising me in the best way possible. Ryan Wong Our magazine is the culmination of hardworking by writers, editors, Emily Yao designers, artists, scientists, creators, and idealists who value the work Can Yumuk done on the bench and on the pages of this magazine. We hope you find all the articles informative, and hope that we can spark your Andrea Zhang own creativity and passion for understanding the very com- plexities that define our personalities and minds. It’s been an honor being a part of such a wonderful Martinelli Valcin community of dedicated and passionate individuals, Valentina Wicki and I can’t wait to see where we go next. Emily Yao -Olivia Nguyen (Editor-In-Chief) the nerve • 2016-17 5 Artwork by Anastasia Kapitonava 6 the nerve • 2016-17 THE DIFFUSIVE MEMRISTOR: A Circuit Element That Emulates Calcium Movement and Plasticity in Neurons By Gabrielle Abad parts of the circuit. Unlike normal resistors that have a set resistance value, the memris- Remember scouring the pages of tor has a varying resistance that depends on “Where’s Waldo?” hoping to find that set of the current flowing through it at any point in stripes among the chaos? We, as humans, find time. The memristor relies on its non-volatile this fairly simple and can accomplish it with property - a characteristic that refers to mem- ease (and a little bit of patience). Comput- ory storage. If something has this property, it ers, on the other hand, must be programmed can retain data even if its power supply is cut to do something like this. The human brain off. An example is the hard disk drive used by performs this task and others more accurate- your computer. When something, say this ar- ly and more quickly than any computer. But, ticle, is saved to this form of storage and then despite the brain being far more energy effi- the computer is turned off, the article in its cient, engineers and scientists have attempted most recent form can still be retrieved when to model it using software run on traditional the computer is later turned on. The mem- computer hardware. Yes, these programs du- ristor behaves this same way by being able plicate the decisions reached by our brains. to remember its most recent resistance even However, they do not mimic the processes though its power supply is cut off. The first our brains perform to reach these decisions. memristors behaved like neurons by simulat- Developments have occurred so that ing quick changes that occur when sending hardware is being built to act more like neu- and receiving signals, but did not replicate the rons. Why focus on the neuron? It is the ba- neuron’s plasticity, the brain’s ability to modify sic working unit of the nervous system and itself, or the neuron’s behavior during the peri- its main job is to transmit information to oth- od of time after a signal has been transmitted. er cells. Because of these neurons, the brain Jianhua Yang, an electrical engineer at functions the way it does. Exploration is large- University of Massachusetts Amherst, and his ly being spent on developing a relatively new team focused on the movement of calcium circuit element called the memristor, a con- across the gap between two neighboring neu- catenation between “memory” and “resistor,” rons. Calcium signals for the release of chem- to mimic the neuron. A resistor is crucial to a icals called neurotransmitters that allow for circuit as it limits the flow of current through the communication between neurons. During it – high resistance allows a small amount of signaling, calcium rushes into the synapse, the current to flow and low resistance allows a gap between neighboring neurons. This caus- large amount of current to flow. Current is the es necessary neurotransmitters to be released, flow of charge through a circuit and allows thus relaying the proper information across the circuit to operate. Too much current at neurons. After signaling, calcium remains in once can result in burning out and breaking the synapse and slowly diffuses back to its the nerve • 2016-17 7 channels. To better model this phenomenon, a outside of this time window, there was no in- device called the diffusive memristor, based on crease in conductance; and at times, even a the random movement of metal nanoparticles decrease in conductance occurred. There was due to external forces, was built. This device no change, or sometimes a decrease, in how consists of a layer of a dielectric film embed- easily current could flow through the device ded with silver nanoparticles, which are anal- compared to its initial state. This increase/ ogous to calcium, sandwiched between either decrease in conductance is analogous to the two platinum or gold inert electrodes, analo- strengthening and weakening of the connec- gous to two neighboring neurons. A dielectric tions between neurons when we learn new material is a good insulator (does not allow for tasks. Because this similarity occurs on a electric current to flow) that does not impede physical level, the memristor’s behavior un- but instead slightly reacts to an external elec- der these conditions can be called an emula- tric forces. An electrode, opposite of a dielec- tion, not just a simulation, of the movement tric material, is a good conductor and is used to of calcium between the neighboring neurons. establish a connection and allows for current Because the neuron and its functions are to flow in and out of a nonmetallic material. more complex than just its process of calcium When voltage was supplied to the device, flow and its characteristic of plasticity, it can- the silver nanoparticles filled and bridged not be said that the diffusive memristor built by the gap between the electrodes by form- Yang and his team emulates the neuron exact- ing small filaments. Current was allowed to ly. However, showing that these processes can flow from one electrode to the other in this be demonstrated on a hardware level opens low resistance state of the memristor. When a new door in neural computing and to the voltage was turned off and as the filaments many possibilities that come with developing broke down, the memristor returned to its new hardware to mimic the brain’s functions high resistance state. However, this did not and moving past just creating software to do so. happen immediately. Even without voltage applied to it, the memristor remained in its low resistance state as the silver nanoparticles slowly broke apart and moved back to either of the electrodes. This simulated calcium flow after the neuron receives a signal. Replicating the nature of plasticity in neurons became the ultimate goal of Yang and his team. First, voltage was applied to the memristor and then was turned off. If voltage was ap- References: plied again quickly, before the silver nanoparticles had enough time to settle back onto the Zhongrui Wang, Saumil Joshi, Sergey E. Savel’ev, Hao Jiang, Rivu Midya, Peng Lin, Miao Hu, electrodes, the device’s conductance, which Ning Ge, John Paul Strachan, Zhiyong Li, Qing is a property that describes the ease in which Wu, Mark Barnell, Geng-Lin Li, Huolin L. Xin, R. current flows through a material, increased as Stanley Williams, Qiangfei Xia, J. Joshua Yang. compared to its initial conductance. If voltage “Memristors with diffusive dynamics as synaptic was turned off and then applied again multi- emulators for neuromorphic computing.” Nature ple times within a certain amount of time, the Matierials, 26 September 2016. Web. 18 October memristor’s overall conductance increased. 2016. Therefore, current could flow more easily through the device as compared to its initial state. Contrasting this, if voltage was applied 8 the nerve • 2016-17 Srijesa Khasnabish Brief History of Zika Virus Microcephaly caused specifically by maternal Zika Virus Zika Virus is a mosquito borne illness that was first detect- infection can be harmful because it not only causes impaired ed in humans in 1952 [1].

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