The science news of the week: It has long been known that strong emotions can turn one gray, sometimes literally overnight. War, natural disasters, and sudden personal tragedies are particularly common. People turn gray and, due to natural causes, their hair loses pigment as they age. It’s possible to live with it and eventually use hair dyes. But making gray hair disappear on its own is something few people have ever heard of. Until Associate Professor Martin Picard of Columbia University took it upon himself to study the subject. “He conducted a study with 14 volunteers, ranging in age from nine to 65, who had gray and completely gray hair.” Samples of these hairs were subjected to high-resolution scanning to determine exactly how much pigment they had lost. An interesting feature was revealed: in some cases, the beginning of hair color loss was observed, but then the process slowed down. By comparing the color variations with the diaries of the experiment participants, who recorded periods of calm and stress throughout the year, the scientists found a certain correlation between stress cycles and hair pigmentation loss. “One of these people went on vacation, and during that time, five of his hairs darkened again,” Picard notes.
Episodes The end of the story: Podcast Advertising By analyzing hundreds of proteins in hair, scientists have discovered a link between gray hair and protein mitochondria – indicators of energy expenditure at the cellular level and metabolic stress. Using a mathematical model to extrapolate the results of their research to a larger number of people of different ages, scientists have hypothesized that graying and gray hair can actually regain its former color in some cases. And although this seems to contradict the study conducted on mice, the discrepancy can be explained by the difference between hair follicles in mice and humans. “Understanding the mechanisms that allow gray hair to regain youthful pigmentation can tell us a lot about the process of human aging and how stress affects this process,” emphasizes Martin Picard. However, researchers are not in a hurry to reassure those who are worried about their gray hair. They say that partial hair color restoration is possible, but only up to a certain age, so it is easy to turn gray prematurely due to stress or other biological reasons, but it is hardly possible to become a fiery brunette again in old age without the help of dye.
Pets have provided us humans with invaluable services during the pandemic. The results of several studies incontrovertibly show that they helped us cope with stress and overcome feelings of loneliness. But we have somehow influenced our pets, haven’t we? According to a group of researchers from the University of York and the University of Lincoln – and here cat lovers nod their heads in agreement, while dog lovers furrow their brows in skepticism – cats have become more affectionate towards their owners during lockdown. Scientists have developed a questionnaire for owners of various pets, from horses and reptiles to birds and fish, not forgetting dog and cat owners, to find out how the pandemic has affected them. Of the more than five thousand people who responded, more than 65% noticed changes in their pets’ behavior during the first lockdown in 2020. Survey participants were asked to talk about their pets, their relationship with them, and their own psychological state. In general, many owners have found that their relationships with their pets have improved, with the exception of dog owners who have found changes for the worse. “My dog has started demanding things from me all the time and howls when I leave the house, even if I am in the yard and she sees me,” wrote one respondent. “I can’t imagine what will happen to her when I have to go to work.” About 10% of dog, cat, and horse owners have noticed that the changes annoy their pets, while 30% say the animals have become more comfortable and relaxed, and another 15% have even noticed an increase in strength and energy. And about a third of all respondents, mostly cat and dog owners, said their pets started following them more closely. One of the main issues highlighted by dog owners was the change in walking and socialization regime. “My dog lacks communication, she doesn’t understand what’s going on,” writes one respondent. “Labradors are social dogs, and my dog doesn’t understand why everyone used to want to pet her, but now they cross the street.” This may seem strange to someone (not familiar with the psychology of these animals), but cats also crave communication. “My cat is a registered therapist,” laments another respondent, “and we really miss regular visits from our fans (it’s written exactly like that). We can’t wait for the day when we can visit them again: he misses their adoration so much”. It is interesting to note that owners who had psychological problems prior to the lockdown were less likely to notice changes in their pets than those who developed problems specifically during the pandemic. The researchers suggest that the increased attachment observed in 35.9% of cats to their owners may be a result of changes in the behavior of the owners themselves. During quarantine, owners were more likely to seek out physical contact and pay special attention to their pets. This, in turn, may have led the cats to actively beg for treats and negotiate for other privileges. One of the authors of the study (whose results were published in the International Journal of Environmental Research and Public Health), Emily Shusmit of York University, acknowledges that the questionnaire had a number of shortcomings, notably that people’s psychological state at the time may have influenced their responses, making it not entirely objective. Also, the vast majority of respondents were women, which may not accurately reflect the mood of the population as a whole. And yet, the research shows that changing our habits has a big impact on the pets we share our homes with, and that they are ready to appreciate the increased attention we give them.
How do events that happen to us not get jumbled up in our heads, but present themselves as a sequential chain? As an international team of scientists from France and the Netherlands has discovered, it is all down to the so-called “time neurons” – the cells of the hippocampus that perform the function of short-term memory and are responsible for the subsequent transfer of information to long-term memory. It is these neurons that allow us to reproduce the correct sequence of events. In fact, as is often the case, such cells, which are responsible for the sequential arrangement of events in our memory, were first discovered in rats. However, the mechanism of encoding episodic memory (i.e., memory of autobiographical events, including time and place of action and all related information) in humans remained a matter of speculation. To turn suppositions into facts, researchers led by neurobiologist Leila Reddi of the French Center for Cognitive Brain Research conducted studies on 15 epilepsy patients who had already had microelectrodes implanted in their hippocampi. In the experiments, participants were presented with a series of images in a particular order and asked to remember that order. At the same time, the electrodes recorded the response of individual neurons in the hippocampus during the display of images, during the intervals when no images appeared on the screen, and during the pauses when participants were asked to guess what the next image would be. In this way, the scientists say, they discovered both the neurons involved in the process of memorizing and reproducing images and those neurons that were activated in the absence of an image. These neurons were responsible for encoding time even in moments when nothing was happening. “Temporal modulations during these pauses could not be elicited by external stimuli,” the researchers wrote in their paper, published in The Journal of Neuroscience. “Instead, they observed a temporal signal that evolved as a result of participants’ perceptual changes while anticipating the next dose of information.” In other words, even when nothing is happening, the timer in our head keeps ticking. Researchers do not rule out the possibility that it is precisely at such moments that “time neurons” perform multilevel work, recording the “what, where and when” related to a particular event and creating a clear memory picture from scattered elements. The phenomenon of subjective “mental time travel” is a cornerstone of episodic memory, scientists write, and neurons in the hippocampus allow us to vividly recall events that occurred at a specific time and place.