Through her studies on roundworms, Cori Bargmann is uncovering how neurons and genes affect behavior. Because many of the gene mechanisms in roundworms mimic those of mammals, Bargmann is able to manipulate certain genes and observe how that affects changes in behavior. For example, in one study she manipulated a gene that caused the male worms to bumble around while trying to mate, ultimately failing. Bargmann developed the Brain Research Advancing Innovative Neurotechnologies Initiative, which researches the root causes of conditions such as Alzheimer's and autism by looking at connections between brain function and behavior. Bargmann is the Torsten N. Wiesel Professor in the Lulu and Anthony Wang Laboratory of Neural Circuits and Behavior at Rockefeller University.As New York City's first Ebola patient, Craig Spencer became the target of media criticism. However, he wasn't just a patient — Spencer had spent five weeks in West Africa helping people fight the deadly virus, where it had become the largest epidemic in history, killing more than 6,300 people. Though Spencer infected no one else and is now Ebola-free, his case brought to light several controversies surrounding Ebola treatment in the US, as well as raised awareness of the epidemic raging in Guinea, Liberia, and Sierra Leone. Spencer is a physician at New York Presbyterian-Columbia University Medical Center.Cynthia Kenyon joined Google's Calico venture last year, where she helps a team of scientists develop methods to slow aging and prevent age-related diseases. The goal of Calico is to extend human lives by up to 100 years. Kenyon gained prominence in the science community in 1993 for her discovery that altering a single gene in roundworms could double their life span. Since then, Kenyon has pioneered many more breakthroughs in aging research, including pinpointing which genes help us live longer and determining that a common hormone-signaling pathway controls the rate of aging in several species, humans included. Kenyon is the vice president of aging research at Calico.Have you ever wondered how a single memory can last for decades and why your brain chooses to store some memories and not others? That's part of what Sebastian Seung is trying to figure out by mapping the hundreds of billions of connections in our brains called the connectome. Mapping all 7,000 connections of a tiny worm took scientists 12 years, which gives you some idea of the colossal challenge that Seung has accepted. To help him out, he's asking the world to participate through the Citizen science project he established called EyeWire, which turns brain-mapping into a game. If he succeeds, he'll create a new way to see the brain. Seung is a professor of computer science at the Princeton Neuroscience Institute.Holmes dropped out of Stanford during her sophomore year to create Theranos, a blood-testing company that uses a prick of blood to get the same test results as you'd get from an entire vial. The concept is disrupting and revolutionizing the industry by making blood tests faster, simpler, and, most important, cheaper. Theranos has raised $400 million in funding, making Holmes the youngest self-made female billionaire in the US. Holmes is the founder and CEO of Theranos.Jennifer Doudna developed CRISPR, a method of genetic engineering that allows scientists to make precise genetic changes relatively easily. Last November, CRISPR saw its first major success in two female monkey twins, Mingming and Lingling, who were born healthy but with specific genetic mutations created through the technology. But it's not without drama: The development of CRISPR ignited the scientific world with controversy after Chinese researchers had experimented with genetic engineering on a human embryo. Doudna is a professor of molecular and cell biology at the University of California at Berkeley.Nina Tandon, CEO and cofounder of EpiBone, is revolutionizing medicine. Her company is the first in the world to use a patient's stem cells to grow human bone that can then be used to repair bone defects like bone loss. Ideally, these bones can be grown to the exact shape and size needed and are easily implanted into the body because they are made from the patient's own cells. Tandon was named a TED senior fellow last year and she's also one of Business Insider's40 under 40: People to watch in 2015. Tandon is the CEO and cofounder of EpiBone.The trillions of microorganisms, known as microbiomes, that live in the gut are composed differently for every person and can influence a number of things, including seasonal allergies and autism. By collecting microbiome samples for everything from plants to dogs, Jack Gilbert hopes to figure out how unique combinations of genetics and environments affect our health. His many projects, including the Home and Hospital Microbiome projects, collect samples from different people and surfaces, analyze each, and provide every person with customized results. He's also launched the kittybiome project on Kickstarter, to study the gut bacteria of cats around the world. Gilbert is an associate professor at the University of Chicago in the department of ecology and evolution.Since the dawn of the 20th century there have been more breakthroughs in neuroscience than during any other century. Yet there are still many aspects of the human brain that we're no where near completely understanding. For example, what areas of the brain are responsible for consciousness and personality? To help solve these mysteries, Katrin Amunts is leading a team of researchers who are carefully constructing a 3D map of the brain. The team announced last year that they'd made the most detailed map of the brain ever, which should lead to unprecedented insights into the construction and organization of the brain and how it drives our behavior. Amunts is a professor at Jülich Research Centre in Germany and the director of the Cecile and Oskar Vogt Institute for Brain Research at the Heinrich Heine University.While engineers are hard at work designing prosthetics with more flexibility and dexterity than ever before, John Donoghue is figuring out how patients can control those prosthetics just by using their brains — the same way they would control a real arm or leg. Donoghue leads the BrainGate2 project, which is developing technologies to “restore communication, mobility, and independence of people with neurologic disease, injury, or limb loss.” In 2015, Donoghue announced that he will be spending the next year leading the launch of a new research center in Switzerland focused on bio- and neuro-engineering. Donoghue is the Henry Merritt Wriston Professor in the department of neuroscience at Brown University, director of the Brown Institute for Brain Science, and director of the Center of Excellence for Neurorestoration and Neurotechnology, Rehabilitation R&D Service, department of Veterans Affairs Medical Center, Providence, Rhode Island.Ten years ago, Karl Deisseroth was one of the only people in the world who thought it might be possible to control neurons by making them genetically sensitized to light. Today, thousands of labs across the globe are using Deisseroth's method, called optogenetics, to better understand the human brain and devise treatments for brain disease and mental-health conditions. In 2010, the journal Nature Methods named optogenetics the “Method of the Year,” and in 2014 Deisseroth was co-awarded the Keio Medical Science Prize, which recognizes significant contributions in medical and life sciences that promote the peace and prosperity of mankind. Deisseroth is the D. H. Chen Professor of Bioengineering and of Psychiatry and Behavioral Sciences at Stanford University.