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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.

Unexplored neural circuit modulates memory strength -- ScienceDaily

"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."

The Brain Learns Completely Differently than We've Assumed Since the 20th Century - Neuroscience News

The newly suggested learning scenario indicates that learning occurs in a few dendrites that are in much closer proximity to the neuron, as opposed to the previous notion. “Does it make sense to measure the quality of air we breathe via many tiny, distant satellite sensors at the elevation of a skyscraper, or by using one or several sensors in close proximity to the nose? Similarly, it is more efficient for the neuron to estimate its incoming signals close to its computational unit, the neuron,” says Kanter. Hebb’s theory has been so deeply rooted in the scientific world for 70 years that no one has ever proposed such a different approach. Moreover, synapses and dendrites are connected to the neuron in a series, so the exact localized site of the learning process seemed irrelevant. Another important finding of the study is that weak synapses, previously assumed to be insignificant even though they comprise the majority of our brain, play an important role in the dynamics of our brain. They induce oscillations of the learning parameters rather than pushing them to unrealistic fixed extremes, as suggested in the current synaptic learning scenario.

Attention deficit disorders could stem from impaired brain coordination: Researchers uncover link absent between brain regions in attention deficit hyperactivity disorder, schizophrenia -- ScienceDaily

When the researchers attached probes to the mice to measure brain activity, they found mice without ErbB4 had brain regions that were acting independently, rather than together in synchrony. In particular, the researchers studied the prefrontal cortex -- normally associated with decision-making -- and the hippocampus -- a region that supports memory. These two regions coordinate for a variety of brain tasks, including memory and attention. "We found top-down attention, previously thought to be controlled by the prefrontal cortex, also involves the hippocampus in a manner where the two regions are highly synchronized when attention is high," says Mei. "Our findings give importance to synchrony between the prefrontal cortex and hippocampus in top-down attention and open up the possibility that attention deficit disorders, like ADHD, might involve impairments in the synchrony between these two regions." According to the new study, ErbB4 coordinates a cascade of brain signals that "bridge" the two regions. ErbB4 itself encodes a receptor found on the surface of brain cells. The study found that when a protein (neuregulin-1) attaches to the ErbB4 receptor, it triggers a chain reaction that ultimately determines neurotransmitter levels in the prefrontal cortex and hippocampus. Without ErbB4, neurotransmitter levels go awry. The researchers discovered mice lacking ErbB4 have low levels of a particular neurotransmitter -- GABA, or gamma-aminobutyric acid -- in their brain. Low GABA levels can lead to impaired top-down attention in the prefrontal cortex, and impairs how the prefrontal cortex can efficiently coordinate with the hippocampus. The researchers concluded that ErbB4 helps link the two brain regions to maintain attention.

Older adults grow just as many new brain cells as young people -- ScienceDaily

The researchers from Columbia University and New York State Psychiatric Institute found that even the oldest brains they studied produced new brain cells. "We found similar numbers of intermediate neural progenitors and thousands of immature neurons," they wrote. Nevertheless, older individuals form fewer new blood vessels within brain structures and possess a smaller pool of progenitor cells -- descendants of stem cells that are more constrained in their capacity to differentiate and self-renew.

When the brain's wiring breaks: Key molecular details of a common type of brain injury and a possible new treatment strategy -- ScienceDaily

"Neurologists know this," said Taylor, a member of the UNC Neuroscience Center. "It's why they promote physical therapy and retraining for people who suffer head injury. During this extended period of excitability, PT and retraining can help guide injured neurons along beneficial pathways."

Is your stress changing my brain? Stress isn't just contagious; it alters the brain on a cellular level -- ScienceDaily

The study's lead author, Toni-Lee Sterley, a postdoctoral associate in Bains' lab said, "What was remarkable was that CRH neurons from the partners, who were not themselves exposed to an actual stress, showed changes that were identical to those we measured in the stressed mice."

Birth of new neurons in the human hippocampus ends in childhood: Adult 'neurogenesis,' observed in other species, appears not to occur in humans -- ScienceDaily

The researchers found plentiful evidence of neurogenesis in the dentate gyrus during prenatal brain development and in newborns, observing an average of 1,618 young neurons per square millimeter of brain tissue at the time of birth. But the number of newborn cells sharply declined in samples obtained during early infancy: dentate gyrus samples from year-old infants contained fivefold fewer new neurons than was seen in samples from newborn infants. The decline continued into childhood, with the number of new neurons declining by 23-fold between one and seven years of age, followed by a further fivefold decrease by 13 years, at which point neurons also appeared more mature than those seen in samples from younger brains. The authors observed only about 2.4 new cells per square millimeter of DG tissue in early adolescence, and found no evidence of newborn neurons in any of the 17 adult post-mortem DG samples or in surgically extracted tissue samples from 12 adult patients with epilepsy.

Understanding the smallest brain circuits: Researchers reveal how anatomically distinct microcircuit brain networks suppress each other, compete and collaborate -- ScienceDaily

"We observe that when some neurons speed up, others slow down-and they do this in a coordinated fashion over several seconds," Galán said. "What we are discovering here, revealing for the first time, is a mode of operation of the brain circuits that shows you cannot have all of your networks operating at once," he said. Galán and his team explain those two anatomically distinct and competing networks in the smallest of the brain's microcircuits, calling them "anti-correlated cortical networks," in a recent issue of Scientific Reports. Co-authors include biology Professor Hillel Chiel and undergraduate students Nathan Kodama (first author), Tianyi Feng, James Ullett and Siddharth Sivakumar. Galán said the discovery was especially gratifying because it culminates the testing of a mathematical model he developed a decade ago. "That was a theoretical prediction-the idea that the wiring of brain circuits could be inferred from their spontaneous activity," he said. "When we were finally able to test this idea experimentally, we discovered the competing neural networks; it all came together in this study."

New neurons in the adult brain are involved in sensory learning -- ScienceDaily

The scientists from the Institut Pasteur and the CNRS observed that the new neurons were able to react differently to an odor depending on the consequences associated with that sensory experience, such as whether or not there would be a reward. They also demonstrated that olfactory learning, in which the mice had to associate an odor with positive reinforcement, became easier once the new neurons had been activated. Finally, simply activating these adult-born neurons could be assimilated with a reward-predicting odor. In short, this research shows that adult-born neurons are involved in the value associated with sensory stimuli rather than just the identification of the nature of a given sensory stimulus. It demonstrates that reward-motivated learning depends largely on adult neurogenesis.

Memories and recursion to the mean

The behavioral data revealed that as the rat awaited the second stimulus of the trial, the memory of the first stimulus shifted towards the mean of preceding stimuli. The experiment thus confirmed the sliding of memory towards the expected value, a phenomenon that earlier studies have termed 'contraction bias.'

Neurons get the beat and keep it going in drumrolls -- ScienceDaily

The researchers recorded the activities of individual neurons in the hippocampus, which is located in the lower center of the brain, with a robotic device called a patch clamp. It's a hollow glass needle one micron in diameter that latches onto a single neuron via suction and measures its electrical activity. The researchers observed electrical rumblings, symbolized here by a drumroll. And they observed spikes, symbolized here by a cymbal crash. Though the pattern of rumblings wasn't uniform, it rose and fell like a drumroll undulating between softer and louder volumes. Spikes occurred much more rarely than drumbeats, but with notable timing. "The spikes repeated in the same spots with high precision, so they weren't just random," Singer said. "They came around the peaks of rumblings, not always right on top of a peak but within a hair of it." It would be like a cymbal crash hitting not every time, but every few times the undulating drumroll topped a volume peak. And the drumroll-cymbal-crash patterns sustained themselves for surprisingly long periods. "The time periods of activity that was structured like this were much longer than we expected," Singer said. "People have shown sustained periods of signaling like this for 100 to 300 milliseconds before, but this appears to be the first time it's been seen for 900 milliseconds (nearly a full second), and it may go on even longer."

Midbrain 'start neurons' control whether we walk or run -- ScienceDaily

The researchers identify populations of 'start neurons' and show, for the first time, how the two regions in the midbrain can act both in common or separately to control speed and to select context dependent locomotor behaviours. "By identifying the midbrain 'start' neurons we complement a previous study where we found 'stop cells' in the brainstem that halt locomotion. Together, the start and stop cells define the episodic nature of locomotion," says Ole Kiehn. The study breaks new grounds in locomotor control and is important for understanding the normal brain function in mice. And the authors believe that the results might benefit humans with disabled locomotion as well.