Beta rhythms, or waves of brain activity with an approximately 20 Hz frequency, accompany vital fundamental behaviors such as attention, sensation and motion and are associated with some disorders such as Parkinson’s disease. Scientists have debated how the spontaneous waves emerge, and they have not yet determined whether the waves are just a byproduct of activity, or play a causal role in brain functions. Now in a new paper led by Brown University neuroscientists, they have a specific new mechanistic explanation of beta waves to consider.
The new theory, presented in the Proceedings of the National Academy of Sciences, is the product of several lines of evidence: external brainwave readings from human subjects, sophisticated computational simulations and detailed electrical recordings from two mammalian model organisms.
“A first step to understanding beta’s causal role in behavior or pathology, and how to manipulate it for optimal function, is to understand where it comes from at the cellular and circuit level,” said corresponding author Stephanie Jones, research associate professor of neuroscience at Brown University. “Our study combined several techniques to address this question and proposed a novel mechanism for spontaneous neocortical beta. This discovery suggests several possible mechanisms through which beta may impact function.”
Making waves
The team started by using external magnetoencephalography (MEG) sensors to observe beta waves in the human somatosensory cortex, which processes sense of touch, and the inferior frontal cortex, which is associated with higher cognition.
They closely analyzed the beta waves, finding they lasted at most a mere 150 milliseconds and had a characteristic wave shape, featuring a large, steep valley in the middle of the wave.
The question from there was what neural activity in the cortex could produce such waves. The team attempted to recreate the waves using a computer model of a cortical circuitry, made up of a multilayered cortical column that contained multiple cell types across different layers. Importantly, the model was designed to include a cell type called pyramidal neurons, whose activity is thought to dominate the human MEG recordings.
They found that they could closely replicate the shape of the beta waves in the model by delivering two kinds of excitatory synaptic stimulation to distinct layers in the cortical columns of cells: one that was weak and broad in duration to the lower layers, contacting spiny dendrites on the pyramidal neurons close to the cell body; and another that was stronger and briefer, lasting 50 milliseconds (i.e., one beta period), to the upper layers, contacting dendrites farther away from the cell body. The strong distal drive created the valley in the waveform that determined the beta frequency.
Meanwhile they tried to model other hypotheses about how beta waves emerge, but found those unsuccessful.
With a model of what to look for, the team then tested it by looking for a real biological correlate of it in two animal models. The team analyzed measurements in the cortex of mice and rhesus macaques and found direct confirmation that this kind of stimulation and response occurred across the cortical layers in the animal models.
“The ultimate test of the model predictions is to record the electrical signals inside the brain,” Jones said. “These recordings supported our model predictions.”
Beta in the brain
Neither the computer models nor the measurements traced the source of the excitatory synaptic stimulations that drive the pyramidal neurons to produce the beta waves, but Jones and her co-authors posit that they likely come from the thalamus, deeper in the brain. Projections from the thalamus happen to be in exactly the right places needed to deliver signals to the right positions on the dendrites of pyramidal neurons in the cortex. The thalamus is also known to send out bursts of activity that last 50 milliseconds, as predicted by their theory.
With a new biophysical theory of how the waves emerge, the researchers hope the field can now investigate whether beta rhythms affect or merely reflect behavior and disease. Jones’s team in collaboration with Professor of Neuroscience Christopher Moore at Brown is now testing predictions from the theory that beta may decrease sensory or motor information processing functions in the brain. New hypotheses are that the inputs that create beta may also stimulate inhibitory neurons in the top layers of the cortex, or that they may may saturate the activity of the pyramidal neurons, thereby reducing their ability to process information; or that the thalamic bursts that give rise to beta occupy the thalamus to the point where it doesn’t pass information along to the cortex.
Figuring this out could lead to new therapies based on manipulating beta, Jones said.
“An active and growing field of neuroscience research is trying to manipulate brain rhythms for optimal function with stimulation techniques,” she said. “We hope that our novel finding on the neural origin of beta will help guide research to manipulate beta, and possibly other rhythms, for improved function in sensorimotor pathologies.”
My tummy is blushing now.
People Were Asked: ‘What’s The Coolest Thing Most People Don’t Know About Their Own Body?’
Both hemispheres of the brain process numbers
Researchers of the Jena University (Germany) and of the Jena University Hospital located an important region for the visual processing of numbers in the human brain and showed that it is active in both hemispheres. In the ’Journal of Neuroscience’ the scientists published high resolution magnetic resonance recordings of this region.
The human brain works with division of labour. Although our thinking organ excels in displaying amazing flexibility and plasticity, typically different areas of the brain take over different tasks. While words and language are mainly being processed in the left hemisphere, the right hemisphere is responsible for numerical reasoning. According to previous findings, this division of labour originates from the fact that the first steps in the processing of letters and numbers are also located individually in the different hemispheres. But this is not the case, at least not when it comes to the visual processing of numbers.
Neuroscientists of the Friedrich Schiller University Jena and of the Jena University Hospital discovered that the visual processing of numbers takes place in a so-called ‘visual number form area’ (NFA) - in fact in both hemispheres alike. The Jena scientists were the first to publish high resolution magnetic resonance recordings showing the activity in this region of the brain of healthy test persons. The area is normally difficult to get access to.
The 'blind spot’ in the brain
In their study Dr. Mareike Grotheer and Prof. Dr. Gyula Kovács from the Institute for Psychology of Jena University as well as Dr. Karl-Heinz Herrmann from the Department of Radiology (IDIR) of the Jena University Hospital presented subjects with numbers, letters and pictures of everyday objects. Meanwhile the participants’ brain activity was recorded using magnetic resonance imaging (MRI). Thus the researchers were able to clearly identify the region in which the visual processing of numbers takes place. The small area at the underside of the left and right temporal lobe reacted with increased activity at the presentation of numbers. Letters and other images but also false numbers lead to a significantly lower brain activity in this area.
Although the Jena team already knew from other scientists’ previous research where they had to look for the area, a lot of developmental work went into the newly published story. “This region has been a kind of blind spot in the human brain until now,” Mareike Grotheer says. And here is why: Hidden underneath the ear and the acoustic meatus, surrounded by bone and air, previous MRI scans showed a number of artefacts and thus obstructed detailed research.
For their study the Jena scientists used a high-performance 3 tesla MRI scanner of the Institute of Diagnostic and Interventional Radiology (IDIR) of the Jena University Hospital. They recorded three-dimensional images of the brain of the test subjects at an unusually high spatial resolution and hence with only very few artefacts. In addition these recordings were spatially smoothed whereby the remaining 'white noise’ could be removed. This approach will help other scientists to investigate a part of the brain that until now had been nearly inaccessible. “In this region not only numbers are being processed but also faces and objects,” Prof. Kovács states.
From an excellent post by Jason Davis
From Washington, D.C., the rings would only fill a portion of the sky, but appear striking nonetheless. Here, we see them at sunrise.
From Guatemala, only 14 degrees above the equator, the rings would begin to stretch across the horizon. Their reflected light would make the moon much brighter.
From Earth’s equator, Saturn’s rings would be viewed edge-on, appearing as a thin, bright line bisecting the sky.
At the March and September equinoxes, the Sun would be positioned directly over the rings, casting a dramatic shadow at the equator.
At midnight at the Tropic of Capricorn, which sits at 23 degrees south latitude, the Earth casts a shadow over the middle of the rings, while the outer portions remain lit.
via x
Have you ever seen a Lybia crab? Often called boxer crabs, or pom-pom crabs, these tiny crustaceans are easily identified by a unique behavior: they hold anemones on their claws to defend themselves from predators, keeping the anemones small enough to wield by limiting their food intake. But how do they get the anemones in the first place? Researchers think they have an answer: by stealing one from another crab, and then splitting it in half to create two identical clones—one for each claw.
Two graduate students, Yisrael Schnytzer and Yaniv Giman, set out to discover how the Lybia crabs acquire their anemones. They spent years observing and collecting crabs (Lybia leptochelis, specifically) from the Red Sea. Given that Lybia crabs are exceptionally well-camouflaged and only a few centimeters across, this was no easy task, but they managed to observe or collect more than 100 individuals.
Every specimen Schnytzer and Giman found was in possession of a pair of anemones, and each anemone belonged to the genus Alicia. Interestingly, the anemones themselves were not found living by themselves; they were only found already living on the claws of Lybia crabs. The researchers decided to study some of the crabs in a laboratory, to see if more observation would solve the mystery of how they acquired their anemones to begin with.
In the lab, the researchers conducted several experiments, the first of which was to take one anemone away from a crab. When left with just one anemone, the crab solved the problem by splitting the remaining anemone into two. The two halves of the anemone would then regenerate into two identical clones, one for each claw, over the course of several days.
The second experiment involved removing both anemones from one crab and placing it in a tank with a crab that still had both its anemones. The result: the two crabs would fight, with the anemone-less crab usually succeeding in stealing one anemone from the other crab. These fights did not tend to result in injuries to the crabs themselves, and once each crab was in possession of one anemone, both crabs would split their anemone into halves to create a pair of clones.
In addition to these experiments, Schnytzer and Giman examined the genes of the anemones found on the wild crabs. Every crab collected from the wild was holding a pair of identical clones. This might mean that anemone theft is rampant among Lybia crabs in the Red Sea, and that it might be the main way that these crabs acquire their anemones.
At any rate, it is clear that the crabs are frequently splitting anemones in two, inducing asexual reproduction in another species and potentially limiting that species’ genetic diversity in the process—a rarity outside the human world.
Based on materials provided by PeerJ and ScienceDaily
Journal reference: Yisrael Schnytzer, Yaniv Giman, Ilan Karplus, Yair Achituv. Boxer crabs induce asexual reproduction of their associated sea anemones by splitting and intraspecific theft. PeerJ, 2017; 5: e2954 DOI: 10.7717/peerj.2954
Image credit: Yisrael Schnytzer
Submitted by volk-morya
See those feathers? The skeleton they found was so well-preserved that scientists were able to examine the pigment cells in the feathers and compare them to those of modern day birds.
And they were able to do this with such accuracy that they know the coloration of this dinosaur. In life it looked something like this.
It just baffles me that we know the color patterns of an animal that has been dead for 161 million years
A bizarre new species of marine worm lacks a number of internal features common to other animals — including an anus, new research shows.
Scientists use lasers to control mouse brain switchboard
Ever wonder why it’s hard to focus after a bad night’s sleep? Using mice and flashes of light, scientists show that just a few nerve cells in the brain may control the switch between internal thoughts and external distractions. The study, partly funded by the National Institutes of Health, may be a breakthrough in understanding how a critical part of the brain, called the thalamic reticular nucleus (TRN), influences consciousness.
“Now we may have a handle on how this tiny part of the brain exerts tremendous control over our thoughts and perceptions,” said Michael Halassa, M.D., Ph.D., assistant professor at New York University’s Langone Medical Center and a lead investigator of the study. “These results may be a gateway into understanding the circuitry that underlies neuropsychiatric disorders.”
The TRN is a thin layer of nerve cells on the surface of the thalamus, a center located deep inside the brain that relays information from the body to the cerebral cortex. The cortex is the outer, multi-folded layer of the brain that controls numerous functions, including one’s thoughts, movements, language, emotions, memories, and visual perceptions. TRN cells are thought to act as switchboard operators that control the flow of information relayed from the thalamus to the cortex.
“The future of brain research is in studying circuits that are critical for brain health and these results may take us a step further,” said James Gnadt, Ph.D., program director at NIH’s National Institute Neurological Disorders and Stroke (NINDS), which helped fund the study. “Understanding brain circuits at the level of detail attained in this study is a goal of the President’s Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative.”
To study the circuits, the researchers identified TRN cells that send inhibitory signals to parts of the thalamus known to relay visual information to the cortex. Using a technique known as multi-electrode recordings, they showed that sleep and concentration affected these cells in opposite ways.
They fired often when the mice were asleep, especially during short bursts of simultaneous brain cell activity called sleep spindles. These activity bursts briefly widen electrical brain wave traces making them look like spindles, the straight spikes with rounded bottoms used to make yarn. In contrast, the cells fired infrequently when the mice were tasked with using visual cues to find food. The results suggested that these cells blocked visual information from reaching the cortex during sleep and allowed its transmission when the mice were awake and attentive.
For Dr. Halassa, a practicing psychiatrist who treats schizophrenia, these surprising results may provide fundamental insights into how the brain controls information transmission, a process that is disrupted in patients with neuropsychiatric disorders. Previous studies suggested that people who experienced more spindles while sleeping were less susceptible to being disturbed by outside noises. Moreover, people with schizophrenia and autism spectrum disorder may experience fewer spindles.
“Spindles may be peepholes into the mysteries of these disorders,” said Dr. Halassa.
To test this idea, the researchers used optogenetics, a technique that introduces light-sensitive molecules into nerve cells. This allowed them to precisely control the firing patterns of visual TRN cells with flashes of laser light. The experiments were performed in well-rested as well as sleep-deprived mice. Similar to what is seen in humans, sleep deprivation can disrupt the ability of mice to focus and block out external distractions.
Well-rested mice needed just a second or two to find the food whereas sleep-deprived mice took longer, suggesting that lack of sleep had detrimental effects on their ability to focus. When the researchers used flashes of laser light to inhibit the firing of optogenetically engineered visual TRN cells in sleep-deprived mice, the mice found the food faster. In contrast, if they used optogenetics to induce sleep-like firing patterns in well-rested mice, then the mice took longer to find food.
“It’s as if with a flick of a switch we could alter the mental states of the mice and either mimic or cure their drowsiness,” said Dr. Halassa.
In a parallel set of experiments the researchers found neighbors of the visual TRN cells had very different characteristics. These neighboring cells control the flow of information to the cortex from limbic brain regions, which are involved with memory formation, emotions and arousal. The cells fired very little during sleep and instead were active when the mice were awake. Dr. Halassa thinks that their firing pattern may be important for the strengthening of new memories that often occurs during sleep. Combined, the results suggest that the TRN is divided into sub-networks that oversee discrete mental states. The researchers think understanding the sub-networks is an initial step in thoroughly exploring the role of the TRN in brain disorders.
Playing Tetris might help reduce the effects of PTSD. Researchers found that those who played it within 4 hours of seeing traumatic events had fewer flashbacks and intrusive memories. They hope to apply the findings to current treatment, which only deals with the effects after they occur.
Btw, you can play Tetris online for free. Any time. All the time.
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