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Clearance of protein linked to Alzheimer's controlled by circadian cycle: Ability of immune system to destroy Alzheimer's-related protein oscillates with daily circadian rhythm -- ScienceDaily
"Circadian regulation of immune cells plays a role in the intricate relationship between the circadian clock and Alzheimer's disease," said Jennifer Hurley, an expert in circadian rhythms, and associate professor of biological science at Rensselaer Polytechnic Institute. "This tells us a healthy sleep pattern might be important to alleviate some of the symptoms in Alzheimer's disease, and this beneficial effect might be imparted by an immune cell type called macrophages/microglia."
Researchers identify potential new means of slowing neurodegenerative diseases -- ScienceDaily
The normal function of Hsp90 is to support healthy cellular processes, but oxidation can have profound effects on the three-dimensional structure of a protein such as Hsp90, altering its function, Franco said.
"By understanding the ways that oxidation modifies the Hsp90 structure, and how the oxidized protein works in the cells, we can look for drugs that bind to the modified structure of Hsp90 and stop its toxic function without affecting the activity of normal Hsp90 in healthy tissues," she said. "That means such drugs should have minimal to no side effects."
Brain tissue inflammation is key to Alzheimer's disease progression
For the first time ever, the researchers showed in living patients that neuroinflammation—or activation of the brain's resident immune cells, called microglial cells—is not merely a consequence of disease progression; rather, it is a key upstream mechanism that is indispensable for disease development.
Damage to white matter is linked to worse cognitive outcomes after brain injury -- ScienceDaily
The most unexpected aspect of our findings was that damage to gray matter hubs of the brain that are really interconnected with other regions didn't really tell us much about how poorly people would do on cognitive tests after brain damage. On the other hand, people with damage to the densest white matter connections did much worse on those tests," explains Justin Reber, PhD, a UI postdoctoral research fellow in psychology and first author on the study. "This is important because both scientists and clinicians often focus almost exclusively on the role of gray matter. This study is a reminder that connections between brain regions might matter just as much as those regions themselves, if not more so."
Unveiling the weaving fractal network of connecting neurons -- ScienceDaily
Nature's fractals benefit from how they grow at multiple scales, said Taylor, who has long turned to fractals as bioinspiration. While trees have the most-recognized form of fractal branching, this work, he said, highlights how neurons are different from trees.
"Whereas the fractal character of trees originates predominantly from the distribution of branch sizes, the neurons also use the way their branches weave through space to generate their fractal character," Taylor said.
Encoding sights
This capability of “visual working memory” feels effortless, but a new MIT study shows that the brain works hard to keep up. Whenever a key object shifts across our field of view — either because it moved or our eyes did — the brain immediately transfers a memory of it by re-encoding it among neurons in the opposite brain hemisphere.
Holistic way to look at neurons in the brain -- ScienceDaily
"This study has essentially provided a 'lookup table' for other neuroscientists, such that if you have information about only one property of a neuron, you can infer the other properties," said Edward Callaway, Ph.D., Professor at the Salk Institute for Biological Studies and an advisor to the Allen Institute for Brain Science, who was not involved in the study. "We need this kind of linking study to figure out what are the true cell types of the brain so we can begin to characterize them. This dataset enables that linking, and it will no doubt prove a great resource for future discovery."
Inside the mind of an animal
Neuroscientists are now discovering other groups of neurons with persistent activity in different brain areas. Using calcium imaging in mice, Andreas Lüthi at the Friedrich Miescher Institute for Biomedical Research in Basel, Switzerland, and Jan Gründemann at the University of Basel searched in the amygdala, which is central to the regulation of a range of emotions and behaviours. The team found two different populations of neurons that displayed sustained but opposing activation when the mice switched between two distinct behaviours6 — exploring the environment and performing defensive behaviours such as freezing.
Specific neurons that map memories now identified in the human brain -- ScienceDaily
"Our study demonstrates that neurons in the human brain track the experiences we are willfully recalling, and can change their activity patterns to differentiate between memories. They're just like the pins on your Google map that mark the locations you remember for important events," Qasim says. "This discovery might provide a potential mechanism for our ability to selectively call upon different experiences from the past and highlights how these memories may influence our brain's spatial map."
Brain tunes itself to criticality, maximizing information processing - ScienceBlog.com
Taking advantage of their ability to continuously track the activity of neurons for more than a week, the researchers first confirmed that network dynamics in the visual cortex are robustly tuned to criticality, even across light and dark cycles.
Next, by blocking vision in one eye, the researchers revealed that criticality was severely disrupted, more than a day before the manipulation affected the firing rates of individual neurons.
Twenty-four hours later, criticality re-emerged in the recordings — at which point individual neurons were suppressed by the visual deprivation.
Study may show why drugs cure brain disorders in mice but not us - STAT
Scientists have now discovered a key reason for that mouse-human disconnect, they reported on Wednesday: fundamental differences in the kinds of cells in each species’ cerebral cortex and, especially, in the activity of those cells’ key genes.
In the most detailed taxonomy of the human brain to date, a team of researchers as large as a symphony orchestra sorted brain cells not by their shape and location, as scientists have done for decades, but by what genes they used. Among the key findings: Mouse and human neurons that have been considered to be the same based on such standard classification schemes can have large (tenfold or greater) differences in the expression of genes for such key brain components as neurotransmitter receptors.
Neuroscientists discover neuron type that acts as brain's metronome: By keeping the brain in sync, these long-hypothesized but never-found neurons help rodents to detect subtle sensations -- ScienceDaily
This type of neuron spikes rhythmically, and in a synchronized manner, independent of external sensations, said Chris Moore, a professor of neuroscience at Brown and the associate director of the Carney Institute for Brain Science. By "setting the beat," the neurons appear to improve rodents' ability to detect when their whiskers are lightly tapped.
Brain waves with approximately 40 cycles per second -- also known as gamma rhythms -- have been studied since the mid-1930s in humans and rodents, and earlier work from Moore's lab showed that boosting the rodents' natural gamma rhythms helped the rodents detect fainter whisker sensations.
"Gamma rhythms have been a huge topic of debate," Moore said. "Some greatly respected neuroscientists view gamma rhythms as the magic, unifying clock that align signals across brain areas. There are other equally respected neuroscientists that, colorfully, view gamma rhythms as the exhaust fumes of computation: They show up when the engine is running but they're absolutely not important."
The metronome-like function of the gamma rhythm has been hypothesized before, but has been largely written off because gamma rhythms change in response to sensations, Moore added. These newly discovered spiking "metronome" neurons -- which spike around 40 cycles a second -- do not.
Adult-born hippocampal neurons bidirectionally modulate entorhinal inputs into the dentate gyrus | Science
Young adult-born granule cells (abGCs) in the dentate gyrus (DG) have a profound impact on cognition and mood. However, it remains unclear how abGCs distinctively contribute to local DG information processing. We found that the actions of abGCs in the DG depend on the origin of incoming afferents.
"We know with flies, just like in mammals, there are neurons involved in positive reinforcement, there are neurons involved in negative reinforcement -- the valence neurons -- and then there are this third set," Tomchik says. "Nobody really knew what they did."
The fruit fly brain contains eight groups of neurons that produce dopamine. Three of them can be found in what's known as the fly brain's "mushroom body." Humans don't have an exact analogous brain section, but other brain regions perform similar functions. In Drosophila melanogaster, aka the fruit fly, the mushroom body is an area highly responsive to odors.
Past fly brain studies have shown that one of the dopamine-producing groups projecting into the mushroom body handles desire-inducing memories connected to odors. ("Mmmm, rotten bananas!") while another guides avoidant behavior related to negative experiences. ("Yikes, dangerous banana smell!")
To find out the role of the third group, referred to as PPL2, research associate and first author Tamara Boto, PhD, trained the flies with an experiment that involved exposing them to fruit-like odors while simultaneously giving them a mild electric shock.
Their conditioned response could be visualized under a microscope by adding a green fluorescent protein that releases light upon reacting to calcium. Calcium ions are released when neurons communicate. Stimulating the PPL2 neurons during the odor experiments changed the brightness of the fluorescence when presented with the odor, an indication that the structures involved in learning and memory had altered the degree of response.
"When we activated this PPL2 set of neurons, it would actually modulate the strength of that memory," Tomchik says. "So we see there are dopaminergic neurons that encode the aversive stimulus itself, and then there is this additional set that can turn the volume up or down on that memory."
Could eating garlic reduce aging-related memory problems? -- ScienceDaily
For the study, the researchers gave oral allyl sulfide to mice that were 24 months old, which correlates to people between 56 and 69 years of age. They compared these mice with 4- and 24-month-old mice not receiving the dietary allyl sulfide supplement.
The researchers observed that the older mice receiving the garlic compound showed better long- and short-term memory and healthier gut bacteria than the older mice that didn't receive the treatment. Spatial memory was also impaired in the 24-month-old mice not receiving allyl sulfide.
Additional experiments revealed that reduced gene expression of neuronal-derived natriuretic factor (NDNF) in the brain was likely responsible for the cognitive decline. This gene was recently discovered by the University of Louisville researchers and is required for long-term and short-term memory consolidation.
The researchers found that mice receiving the garlic compound exhibited higher levels of NDNF gene expression. In addition, recombinant-NDNF protein therapy in the brain restored the cognitive abilities of the older mice that did not receive the garlic compound.
Serotonin can regulate gene expression inside neurons -- ScienceDaily
The study revolves around DNA and how it works to form each person's individual biological map. Each cell in the body contains two meters of DNA, the blueprint for all functions of all cells in the body. This DNA is wound around spools of histone proteins (proteins that package DNA in the nucleus of cells, and are heavily prone to chemical modifications that aid in the regulation of gene expression) into structures referred to as nucleosomes. When DNA encoding a specific gene is wound tightly within the spool, that gene is less likely to be expressed. When the gene is not wound as tightly, it is more likely to be expressed. This can affect many functions of a given cell.
Serotonin is a chemical that can transmit signals between neurons in the brain and is involved in the regulation of mood. Selective serotonin reuptake inhibitors, known as SSRIs, alter the amounts of serotonin in the brain, which enables mood changes. When small packages of serotonin are released from a neuron, the resulting signals set up a chain reaction of communication between different parts of the brain.
The research team discovered that a protein called tissue transglutaminase 2 can directly attach serotonin molecules to histone proteins (a process called histone serotonylation), which in turn loosens the spool to enable more robust gene expression. Specifically, they found that in developing rodent brains and human neurons, genes near the part of the spool loosened by the serotonin are more likely to be expressed. They also showed that a specific binding complex enables this process.
This is a neuron on nicotine: Nicotine works inside cells to reinforce addiction -- ScienceDaily
By making movies of cells containing biosensors in a lab dish, the team has discovered that nicotine enters into the endoplasmic reticulum within a few seconds of appearing outside a cell. Furthermore, the nicotine levels are more than enough to affect nAChRs during their assembly and to chaperone additional nAChRs on their journey to the cell surface. As a result, the neurons are more sensitive to the nicotine, which enhances the rewarding feelings after a puff on a tobacco cigarette or an e-cigarette. In other words, the more a person smokes, the more quickly and easily the smoker gets a nicotine buzz. This is part of nicotine addiction.
How Brain Cells Filter Information in Groups - Neuroscience News
For decades, scientists studying the visual system thought that individual brain cells, called neurons, operate as filters. Some neurons would prefer coarse details of the visual scene and ignore fine details, while others would do the opposite. Every neuron was thought to do its own filtering.
A new study led by Salk Institute researchers challenges this view. The study revealed that the same neurons that prefer coarse details could change to prefer finer details under different conditions. The work, which appeared in the journal Neuron on December 31, 2018, could help to better understand neural mechanisms that shape our perceptions of the world.
“We were trying to look beneath the hood and figure out how these filters work,” says Professor Thomas Albright, director of Salk’s Center for Neurobiology of Vision and a senior author of the study.
Ant Colonies Retain Memories That Outlast the Lifespans of Individuals | Science | Smithsonian
Colonies live for 20-30 years, the lifetime of the single queen who produces all the ants, but individual ants live at most a year. In response to perturbations, the behavior of older, larger colonies is more stable than that of younger ones. It is also more homeostatic: the larger the magnitude of the disturbance, the more likely older colonies were to focus on foraging than on responding to the hassles I had created; while, the worse it got, the more the younger colonies reacted. In short, older, larger colonies grow up to act more wisely than younger smaller ones, even though the older colony does not have older, wiser ants.
Ants use the rate at which they meet and smell other ants, or the chemicals deposited by other ants, to decide what to do next. A neuron uses the rate at which it is stimulated by other neurons to decide whether to fire. In both cases, memory arises from changes in how ants or neurons connect and stimulate each other. It is likely that colony behavior matures because colony size changes the rates of interaction among ants. In an older, larger colony, each ant has more ants to meet than in a younger, smaller one, and the outcome is a more stable dynamic. Perhaps colonies remember a past disturbance because it shifted the location of ants, leading to new patterns of interaction, which might even reinforce the new behavior overnight while the colony is inactive, just as our own memories are consolidated during sleep. Changes in colony behavior due to past events are not the simple sum of ant memories, just as changes in what we remember, and what we say or do, are not a simple set of transformations, neuron by neuron. Instead, your memories are like an ant colony’s: no particular neuron remembers anything although your brain does.
New target of alcohol in the brain -- ScienceDaily
"The KCNK13 channel is absolutely required for alcohol to stimulate the release of dopamine by these neurons," said Mark Brodie, professor of physiology and biophysics in the UIC College of Medicine and lead author of the study. "Without the channel, alcohol can't stimulate the release of dopamine, and so drinking is likely less rewarding. We think that the KCNK13 channel presents an extremely exciting new target for drugs that could potentially help people with alcohol use disorder to stop drinking."
Great minds may think alike, but all minds look alike -- ScienceDaily
The (skeleton) structure of the brain is like a road map consisting of many narrow streets (i.e., weak links), and a small fraction of highways each containing thousands of lanes (i.e., very strong links). Such a diverse road map could either be a spontaneous outcome of a random brain activity, or alternatively could be directed by a meaningful learning activity, where the "highways" direct the information flow in the brain.
"A byproduct of dendritic learning is the wide spectrum of link strengths. The dendritic learning enables us to offer an explanation for an additional universal phenomenon observed in all brains and indicates its important role," said Prof. Kanter, whose research team includes Herut Uzan, Shira Sardi, Amir Goldental and Roni Vardi. The underlying mechanism is a fast response of a neuron to its strong entry compared to a slow response to a weak one. "The mechanism is similar to a pool filled through a wide pipe or through a narrow one. The wide pipe fills the pool faster," explained the research team.
Fundamental Rule of Brain Plasticity Discovered - Neuroscience News
Our brains are famously flexible, or “plastic,” because neurons can do new things by forging new or stronger connections with other neurons. But if some connections strengthen, neuroscientists have reasoned, neurons must compensate lest they become overwhelmed with input. In a new study in Science, researchers at the Picower Institute for Learning and Memory at MIT demonstrate for the first time how this balance is struck: when one connection, called a synapse, strengthens, immediately neighboring synapses weaken based on the action of a crucial protein called Arc.
Senior author Mriganka Sur said he was excited but not surprised that his team discovered a simple, fundamental rule at the core of such a complex system as the brain, where 100 billion neurons each have thousands of ever-changing synapses. He likens it to how a massive school of fish can suddenly change direction, en masse, so long as the lead fish turns and every other fish obeys the simple rule of following the fish right in front of it.
Absence epilepsy: When the brain is like 'an orchestra without a conductor' -- ScienceDaily
"Normally the human brain, like an orchestra, is playing beautiful music and every player can understand what the others are playing. We thought that when a seizure started, the 'orchestra of neurons' would play extremely loud and intense music. And when the seizure ended, the neurons would go back to playing monotonous music," Maheshwari said. "Instead, we found that during an absence seizure the volume of the music went down and the 'musicians' were playing music without coordinating with others. Most of them were not playing at all, as if the conductor was not there anymore. When the seizure ended, it was like the conductor had returned and organized the musicians to play harmoniously again."
Acupuncture alters key neurotransmitters
Steffensen is going beyond the previous claims and is studying the neuroscience behind acupuncture. He has shown it to be an effective method of activating pathways from the peripheral nervous system to the central nervous system. Here's how:
Those suffering from withdrawal have dysregulated dopamine levels in the midbrain reward/pleasure system
This causes dysregulation of GABA neurons in this system, and they become hyperactive, inhibiting dopamine neurons and lowering dopamine levels during withdrawl
Lowered dopamine levels is the driving force for relapse
Accupuncture stimulation inhibits GABA neurons
This restores dopamine levels and effectively lowers the driving force for relapse
Melatonin in Synaptic Impairments of Alzheimer's Disease. - PubMed - NCBI
It is reported that both the melatonin deficit and synaptic impairments are present in the very early stage of AD and strongly contribute to the progress of AD. In the mammalian brains, the effects of melatonin are mainly relayed by two of its receptors, melatonin receptor type 1a (MT1) and 1b (MT2). To have a clear idea on the roles of melatonin in synaptic impairments of AD, this review discussed the actions of melatonin and its receptors in the stabilization of synapses, modulation of long-term potentiation, as well as their contributions in the transmissions of glutamatergic, GABAergic and dopaminergic synapses, which are the three main types of synapses relevant to the synaptic strength. The synaptic protective roles of melatonin in AD treatment were also summarized. Regarding its protective roles against amyloid-β neurotoxicity, tau hyperphosphorylation, oxygenation, inflammation as well as synaptic dysfunctions, melatonin may be an ideal therapeutic agent against AD at early stage.
New findings explain how melatonin promotes sleep: Discovery may lead to new therapy for insomnia -- ScienceDaily
The experiments singled out one receptor, MT1, as the mechanism via which melatonin acts to inhibit the specific orexin neurons that wake you up. This discovery could help lead to medications that target only the MT1 receptor instead of multiple receptors, which could lead to fewer side effects for those who take sleep-promoting drugs.
"Melatonin has been used as a sleep drug for many years, but people didn't know how it worked," Thakkar said. "Our research suggests that if you target the melatonin MT1 receptor, you will get the most sleep with minimal side effects."