When it comes to processing power, the human brain just can’t be beat. Packed within the squishy, football-sized organ are somewhere around 100 billion neurons. At any given moment, a single neuron can relay instructions to thousands of other neurons via synapses — the spaces between neurons, across which neurotransmitters are exchanged. There are more than 100 trillion synapses that mediate neuron signaling in the brain, strengthening some connections while pruning others, in a process that enables the brain to recognize patterns, remember facts, and carry out other learning tasks, at lightning speeds. Researchers in the emerging field of “neuromorphic computing” have attempted to design computer chips that work like the human brain. Instead of carrying out computations based on binary, on/off signaling, like digital chips do today, the elements of a “brain on a chip” would work in an analog fashion, exchanging a gradient of signals, or “weights,” much like neurons that activate in various ways depending on the type and number of ions that flow across a synapse....

When you expect a really bad experience to happen and then it doesn’t, it’s a distinctly positive feeling. A new study of fear extinction training in mice may suggest why: The findings not only identify the exact population of brain cells that are key for learning not to feel afraid anymore, but also show that these neurons are the same ones that help encode feelings of reward. The study, published Jan. 14 in Neuron by scientists at MIT’s Picower Institute for Learning and Memory, specifically shows that fear extinction memories and feelings of reward alike are stored by neurons that express the gene Ppp1r1b in the posterior of the basolateral amygdala (pBLA), a region known to assign associations of aversive or rewarding feelings, or “valence,” with memories. The study was conducted by Xiangyu Zhang, an MIT graduate student, Joshua Kim, a former graduate student, and Susumu Tonegawa, professor of biology and neuroscience at RIKEN-MIT Laboratory of Neural Circuit Genetics at the Picower Institute for Learning and Memory at MIT and Howard Hughes Medical Institute....

More than a decade before people with Huntington’s disease (HD) show symptoms, they can exhibit abnormally high levels of an immune-system molecule called interleukin-6 (IL-6), which has led many researchers to suspect IL-6 of promoting the eventual neurological devastation associated with the genetic condition. A new investigation by MIT neuroscientists shows that the story likely isn’t so simple. In a recent study they found that Huntington’s model mice bred to lack IL-6 showed exacerbated symptoms compared to HD mice that still had it. “If one looks back in the literature of the Huntington’s disease field, many people have postulated that reductions to IL-6 would be therapeutic in HD,” says Myriam Heiman, associate professor in MIT’s Department of Brain and Cognitive Sciences and a member of The Picower Institute for Learning and Memory and the Broad Institute of MIT and Harvard. She is senior author of the paper in Molecular Neurodegeneration. Former postdoc Mary Wertz is the lead author....

These days, nearly all the artificial intelligence-based products in our lives rely on “deep neural networks” that automatically learn to process labeled data. For most organizations and individuals, though, deep learning is tough to break into. To learn well, neural networks normally have to be quite large and need massive datasets. This training process usually requires multiple days of training and expensive graphics processing units (GPUs) — and sometimes even custom-designed hardware. But what if they don’t actually have to be all that big, after all? In a new paper, researchers from MIT’s Computer Science and Artificial Intelligence Lab (CSAIL) have shown that neural networks contain subnetworks that are up to one-tenth the size yet capable of being trained to make equally accurate predictions — and sometimes can learn to do so even faster than the originals. The team’s approach isn’t particularly efficient now — they must train and “prune” the full network several times before finding the successful subnetwork. However, MIT Assistant Professor Michael Carbin says that his team’s findings suggest that, if we can determine precisely which part of the original network is relevant to the final prediction, scientists might one day be able to skip this expensive process altogether. Such a revelation has the potential to save hours of work and make it easier for meaningful models to be created by individual programmers, and not just huge tech companies....

We are free to wander, but usually when we go somewhere it’s for a reason. In a new study, researchers at the Picower Institute for Learning and Memory at MIT show that as we pursue life’s prizes, a region of the brain tracks our location with an especially strong predilection for the location of the reward. This pragmatic bias of the lateral septum (LS) suggests it’s a linchpin in formulating goal-directed behavior. “It appears that the lateral septum is, in a sense, ‘prioritizing’ reward-related spatial information,” says Hannah Wirtshafter, lead author of the study in eLife and a former graduate student in the MIT lab of senior author Matthew Wilson, the Sherman Fairchild Professor of Neurobiology at MIT. Wirtshafter is now a postdoc at Northwestern University. Last year, Wirtshafter and Wilson, who has appointments in the Department of Biology and the Department of Brain and Cognitive Sciences, analyzed measurements of the electrical activity of hundreds of neurons in the LS and the hippocampus, a region known for encoding many forms of memory including spatial maps, as rats navigated a maze toward a reward. In Current Biology they reported that the LS directly encodes information about the speed and acceleration of the rats as they navigated through the environment....

The Austrian Association of Entrepreneurs has announced that Edward S. Boyden, the Y. Eva Tan Professor in Neurotechnology at MIT, has been awarded the 2020 Wilhelm Exner Medal. Named after Austrian businessman Wilhelm Exner, the medal has been awarded annually since 1921 to scientists, inventors, and designers who are “promoting the economy directly or indirectly in an outstanding manner." Past honorees include 22 Nobel laureates. “It’s a great honor to receive this award, which recognizes not only the basic science impact of our group’s work, but the impact of the work in the industrial and startup worlds,” says Boyden, who is a professor of biological engineering and of brain and cognitive sciences at MIT. Boyden is a leading scientist whose work is widely used in industry, both in his own startup companies and in existing companies. Boyden is also a member of MIT’s McGovern Institute for Brain Research, Media Lab, and Koch Institute for Integrative Cancer Research. "I am so thrilled that Ed has received this honor," says Robert Desimone, director of the McGovern Institute. "Ed’s work has transformed neuroscience, through optogenetics, expansion microscopy, and other findings that are pushing biotechnology forward too."...

For most students, senior year of college is a time to reminisce with friends and professors, a time to celebrate, and a time to look forward to new beginnings. The Class of 2020 will experience something different. For Steven Truong, a senior in the Department of Biological Engineering, the Covid-19 global pandemic sent him home from MIT to Minnesota, away from friends and colleagues and to where his Vietnamese family relies on his comparatively rich medical knowledge for information. “I think my closest friends and I have been really good at reaching out to each other. But I really do miss the day-to-day interactions because those interactions are what really count,” says Truong. “There's nothing quite like working on a pset with someone at, say 2 a.m. in the morning. It's really part of the MIT experience.” Truong, along with students across the country, now must navigate life at home while trying to complete school work and manage additional stressors that have accompanied the pandemic....

If anything happens to the eyes of the tiny, freshwater-dwelling planarian Schmidtea mediterranea, they can grow them back within just a few days. How they do this is a scientific conundrum — one that Peter Reddien's lab at Whitehead Institute has been studying for years. The lab's latest project offers some insight: in a paper published in Science June 26, researchers in Reddien's lab have identified a new type of cell that likely serves as a guidepost to help route axons from the eyes to the brain as the worms complete the difficult task of regrowing their neural circuitry. Schmidtea mediterranea's eyes are composed of light-capturing photoreceptor neurons connected to the brain with long, spindly processes called axons. They use their eyes to respond to light to help navigate their environment. The worms, which are popular models for research into regeneration, can regrow pretty much any part of their body; eyes are an interesting part to study because regenerating the visual system requires the worms rewire their neurons to connect them to the brain....