Understanding the arrow of time across scales and complexity

Review written by Qiwei Yu (G2, Biophysics)

The stream of time flows inevitably forward and stops for no one. This one-way direction defines an “arrow of time”, which we perceive through the lens of irreversible processes that occur in both inanimate and living worlds. Irreversibility is manifested at both microscopic and macroscopic scales, ranging from the dissolution of an ink droplet in water to the concerted flight of large flocks of birds.

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Isolation Disorganizes Typical Social Interaction and Whole-Brain Genetic Expression in the Bumblebee

Review written by Adelaide Minerva (PNI, G4) and Rebekah Rashford (PNI, G5)

Throughout the COVID pandemic, many of us were faced with profound levels of social isolation which took a toll on both our mental and physical health. This has been especially detrimental for children, whose brains and social skills are still developing. Normally, social experience in early life plays a crucial role in guiding this development; but what happens when that guidance is no longer present? Disruptions to the early social environment have been seen to negatively impact other social species besides humans, such as mice, fish, and some insects. Studying how social isolation may disrupt the development of these highly social species can provide insight into the neural mechanisms underlying  both typical and aberrant behavior at a level of detail not currently possible in human subjects. Taking advantage of one of these highly social species, Dr. Yan Wang and colleagues in the departments of Ecology & Evolutionary Biology and the Center for Biophysics at Princeton used bumblebees to measure the effects of early life social isolation on behavior, gene expression, and whole-brain neuroanatomy. 

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Using Machine Learning to Better Understand Human Behavior

Review written by Paula Brooks (NEU, G6)

How similar are bears and bulls?

If you ask a biologist, she might say that they are pretty similar, since they are both four-legged mammals found in North America. However, if you ask an economist, he might say they are polar opposites, since they are used to describe distinct stock market conditions. The unique way in which individuals organize their semantic knowledge, or general information gained through life experiences, could cause two people to judge the similarity between two animals in very different ways.

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Early life adversity can induce pathological avoidance behaviors in mice, but males with suppressed neurogenesis may step out of their comfort zones

Review written by Amy Ciceu (NEU, 2024)

Early life adversity, ranging from physical and emotional abuse, neglect, and violence, to poverty and unstable home environments, can have an enduring toll on child development. Some children who experience early life adversity may experience detrimental effects in the moment but develop into adults without pathological behavior. On the other hand, for certain children, the impacts of early life adversity increase the likelihood that they will develop neuropsychiatric disorders as adults. For instance, anxiety disorders are more prevalent amongst survivors of early life adversity compared to the general population. Although diverse in the symptoms they present and the treatments they require, anxiety disorders share one feature in common: heightened levels of anxiety. Normally, anxiety helps us steer clear of dangers. However, if ramped up into overdrive, excessive levels of anxiety can fuel a range of maladaptive behaviors.

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Socioeconomic status effects on human health have evolved with industrialization

Review written by Kimberly Sabsay (QCB, G3)

Socioeconomic status (SES), often simplified as absolute material wealth, is often linked to a variety of human health metrics. At a fundamental level, it makes sense that higher SES likely corresponds with access to better medical services, and in turn, better overall health. Studies have shown that, indeed, higher SES is associated with better human health, but the majority of this data comes from high-income countries (HICs). Despite the growing amount of scientific evidence for the apparent gradients in disease risk and survival explained by access to medical care and other health-related lifestyle factors, we cannot be certain that these trends are universal. Understanding the relationship between SES and health is crucial for policy design and to ensure we make economic decisions that do not negatively impact overall human health. Ultimately, the relationships between SES and health can be used to motivate positive change that benefits all of humanity.

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The Termite Wars: How tiny insect engineers shape the African savanna

Review written by Jarome Ali (EEB, G5)

Music by Three Music

On the savannas of Kenya, a battle has been waged for centuries. The landscape hints at how this battle has shaped the entire ecosystem, but it must be viewed from far above. From just a few meters above ground level, the telltale signs are still invisible. However, from the vantage point offered by drone photography or satellite imagery, a clear pattern emerges. Patches of vegetation are spotted across the savanna, in a regular hexagonal layout. This kind of order in the natural world fascinates biologists and begs for an explanation. Researchers at Princeton have been investigating how warring termite colonies (or insect colonies in general), and the underlying resource distribution can drive the emergence of order in the savanna landscape. 

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Bacteria in the human microbiome can inactivate the antidiabetic drug acarbose

Review written by Abigail Stanton (MOL, G2)

Even in the microscopic world, survival of the fittest can make for relentless, and creative, competition. With a limited amount of resources to go around, some bacteria will play dirty to make sure they get their fair share. Actinoplanes sp. SE50/110, a bacterium that lives in the soil, has developed a strategy to fight off competitors: by producing a specialized sugar called acarbose, it can block proteins responsible for sugar uptake and metabolism in its microbial neighbors. This inhibits the growth of other bacteria, leaving more food for Actinoplanes to enjoy. 

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Proton Outflow Associated With Jupiter’s Auroral Processes

Review written by Cecilia Panfil (CHM, 2022) and Alexandra Libby (PNI, GS)

Abstract

Despite Jupiter’s aurora being the brightest in the solar system, the mechanism of its occurrence is not well understood. One peculiar phenomenon on Jupiter is the large quantities of protons in its magnetosphere. Recently, Dr. Jamey Szalay and his team were able to use data from the Juno spaceship to observe the protons flying away from Jupiter. This provides evidence that the protons are coming from Jupiter itself. The electric fields which drive protons away from Jupiter are likely intimately related to Jupiter’s auroral fields. With their novel observation, Szalay et al. provide a clue towards Jupiter’s complex auroral interactions. 

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Exploring the tradeoff between privacy and algorithm performance

Review written by Andy Jones (COS, G3)

In many countries, cameras are nearly ubiquitous in public society. When you go to public places — such as stoplights, stores, or hospitals — a photograph is often taken of you. 

When these photographs are collected into large datasets, they can be useful for developing machine learning (ML) solutions to real-world problems. For example, automated analysis of stoplight photographs could improve traffic flow, and examining customer behavior patterns in clothing stores could improve the shopping experience. However, a large fraction of these photographs contain personal identifying information, such as faces, addresses, or credit card numbers. These photos prompt concerns about the privacy of the individuals identified in them. Thus, at first glance there appears to be a tradeoff between using large datasets of images to train ML algorithms and protecting people’s privacy. But what if the people in these images could somehow be anonymized to protect their privacy, while the images could still be used to build useful ML models?

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AAV: Versatile Viral Hero or Neurotoxic Villain?

Review written by Amy Ciceu (NEU, 2024)

Adeno-associated viruses (AAVs) are some of the most widely used recombinant viral technologies—those that combine different genes to produce unique viral vectors, or tools that convey genetic material into cells—in modern neuroscience. Because they are incapable of being replicated within cells, recombinant AAVs are commonly used in neuroscience research as a means of expressing genes in specific cells. By expressing genes that heighten or dampen the function of certain cells, researchers are able to identify the functions of particular neural circuits.1  This approach can provide scientists with insight into the mechanisms underlying neurobiological processes. To make such circuit-related discoveries, AAVs are typically injected into certain brain regions of animal subjects. After an incubation period, some AAVs encoding fluorescent tracers can induce cells to fluoresce under specialized microscopes, enabling scientists to visualize particular neural circuitry. Furthermore, AAVs have demonstrated clinical potential; for example, AAVs have been used to replenish certain proteins in the treatment of diseases like congenital blindness 2, 3 and spinal muscular atrophy.4, 5 AAV is also currently being investigated as a potential means of treating other brain disorders, including Parkinson’s disease, Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), and more.6

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