The default theme for this site has been updated. For further information, please take a look at the announcement regarding HAF changing its default theme.
Started by Claireliontamer, July 12, 2017, 08:18:49 PM
Quote from: Magdalena on February 11, 2021, 06:11:48 AMQuote from: Icarus on February 10, 2021, 03:47:32 AMI wonder whether Mags and Hermes has had to put up with similar dimwits. Oh, yes. I was telling a young lady that I used to work with that when I was a kid in El Salvador, my friends and I used to play around quicksand. She asked me, "So...how do you know where your loved ones are buried, then?" I said, "We have cemeteries."
Quote from: Icarus on February 10, 2021, 03:47:32 AMI wonder whether Mags and Hermes has had to put up with similar dimwits.
Quote from: No one on February 11, 2021, 06:48:17 AMMmmmmmmmmmmmmmmmm papusas.
QuoteMillions of surgical procedures performed each year would not be possible without the aid of general anesthesia, the miraculous medical ability to turn off consciousness in a reversible and controllable way.Researchers are using this powerful tool to better understand how the brain reconstitutes consciousness and cognition after disruptions caused by sleep, medical procedures requiring anesthesia, and neurological dysfunctions such as coma.In a new study published in the journal eLife, a team led by anesthesiologists George Mashour, M.D., Ph.D. of University of Michigan Medical School, Michigan Medicine, Max Kelz, M.D., Ph.D. of the University of Pennsylvania Medical School, and Michael Avidan, MBBCh of the Washington University School of Medicine used the anesthetics propofol and isoflurane in humans to study the patterns of reemerging consciousness and cognitive function after anesthesia.In the study, 30 healthy adults were anesthetized for three hours. Their brain activity was measured with EEG and their sleep-wake activity was measured before and after the experiment. Each participant was given cognitive tests—designed to measure reaction speed, memory, and other functions—before receiving anesthesia, right after the return of consciousness, and then every 30 minutes thereafter.The study team sought to answer several fundamental questions: Just how does the brain wake up after profound unconsciousness—all at once or do some areas and functions come back online first? If so, which?"How the brain recovers from states of unconsciousness is important clinically but also gives us insight into the neural basis of consciousness itself," says Mashour.After the anesthetic was discontinued and participants regained consciousness, cognitive testing began. A second control group of study participants, who did not receive general anesthesia and stayed awake, also completed tests over the same time period.[Continues . . .]
QuoteAbstract:Understanding how the brain recovers from unconsciousness can inform neurobiological theories of consciousness and guide clinical investigation. To address this question, we conducted a multicenter study of 60 healthy humans, half of whom received general anesthesia for 3 hr and half of whom served as awake controls. We administered a battery of neurocognitive tests and recorded electroencephalography to assess cortical dynamics. We hypothesized that recovery of consciousness and cognition is an extended process, with differential recovery of cognitive functions that would commence with return of responsiveness and end with return of executive function, mediated by prefrontal cortex. We found that, just prior to the recovery of consciousness, frontal-parietal dynamics returned to baseline. Consistent with our hypothesis, cognitive reconstitution after anesthesia evolved over time. Contrary to our hypothesis, executive function returned first. Early engagement of prefrontal cortex in recovery of consciousness and cognition is consistent with global neuronal workspace theory.[¶ added - R]
QuoteScientists have discovered a unique form of cell messaging occurring in the human brain that's not been seen before. Excitingly, the discovery hints that our brains might be even more powerful units of computation than we realized.Early last year, researchers from institutes in Germany and Greece reported a mechanism in the brain's outer cortical cells that produces a novel 'graded' signal all on its own, one that could provide individual neurons with another way to carry out their logical functions.By measuring the electrical activity in sections of tissue removed during surgery on epileptic patients and analysing their structure using fluorescent microscopy, the neurologists found individual cells in the cortex used not just the usual sodium ions to 'fire', but calcium as well.This combination of positively charged ions kicked off waves of voltage that had never been seen before, referred to as a calcium-mediated dendritic action potentials, or dCaAPs.[Continues . . .]
QuoteAbstract:The active electrical properties of dendrites shape neuronal input and output and are fundamental to brain function. However, our knowledge of active dendrites has been almost entirely acquired from studies of rodents. In this work, we investigated the dendrites of layer 2 and 3 (L2/3) pyramidal neurons of the human cerebral cortex ex vivo. In these neurons, we discovered a class of calcium-mediated dendritic action potentials (dCaAPs) whose waveform and effects on neuronal output have not been previously described. In contrast to typical all-or-none action potentials, dCaAPs were graded; their amplitudes were maximal for threshold-level stimuli but dampened for stronger stimuli. These dCaAPs enabled the dendrites of individual human neocortical pyramidal neurons to classify linearly nonseparable inputs—a computation conventionally thought to require multilayered networks.[ ¶ added. -R]
QuoteIt's easy to get distracted - whether you're daydreaming about a special someone while you should be working, or completely going blank and just taking a brain break.Now, scientists have gained a better idea of what actually happens in our brains when we 'zone out', and it looks a lot like a part of the brain is... sort-of falling asleep."Attentional lapses occur commonly and are associated with mind wandering, where focus is turned to thoughts unrelated to ongoing tasks and environmental demands, or mind blanking, where the stream of consciousness itself comes to a halt," the team – led by neuroscientist Thomas Andrillon – wrote in their new paper."Our results suggest attentional lapses share a common physiological origin: the emergence of local sleeplike activity within the awake brain."When you go to sleep, your brain experiences 'slow waves' of brain activity in the delta (1–4 Hz) or theta (4–7 Hz) ranges during non-rapid eye movement sleep. This is the slow descent before you get to the deep, dream-filled rapid eye movement (REM) sleep. In contrast, there's this 'sleeplike activity' while you're awake – called local sleep by scientists. It's relatively well studied by researchers and it happens while you're completely awake, but localized brain activity enters a state which resembles sleep. There are pretty specific times when we know that local sleep happens, particularly when we're really, really tired. But the researchers discovered something that looks very similar to local sleep in well-rested volunteers when their minds were wandering or blanking.[Continues . . .]
QuoteThe enteric nervous system (ENS) in our gut operates a lot like other neural networks in the brain and the spinal cord – so much so that it's often called the 'second brain'. Now a new study has revealed more about how exactly the ENS works.Using a recently developed technique combining high-resolution video recordings with an analysis of biological electrical activity, scientists were able to study the colons of mice, and in particular the way that the gut moves its contents along.One of the key findings was discovering how the thousands of neurons inside the ENS communicate with each other, causing contractions in the gastrointestinal tract to aid the digestive process. Up until now, it wasn't clear how these neurons were able to join forces to do this."Interestingly, the same neural circuit was activated during both propulsive and non-propulsive contractions," says neurophysiologist Nick Spencer from Flinders University in Australia.The team found large bunches of connecting neurons firing to propel the contents of the colon further down the gut, via both excitatory (causing action) and inhibitory (blocking action) motor neurons.The discovery means the ENS is made up of a more advanced network of circuitry, covering a wider section of the gut and involving a greater amount of different types of neurons working in tandem than had previously been thought.Another important finding is that this activity is significantly different from the propulsion that's seen in other muscle organs around the body that don't have a built-in nervous system, such as lymphatic vessels, ureters, or the portal vein."The mechanism identified is more complex than expected and vastly different from fluid propulsion along other hollow smooth muscle organs," the researchers explain in their paper.The team says it backs up the hypothesis that the ENS is in fact the 'first brain' rather than the second one – suggesting that it may have evolved in animals a long time before our actual brains took their current form.[Continues . . .]
QuoteAbstract:How the Enteric Nervous System (ENS) coordinates propulsion of content along the gastrointestinal (GI)-tract has been a major unresolved issue. We reveal a mechanism that explains how ENS activity underlies propulsion of content along the colon. We used a recently developed high-resolution video imaging approach with concurrent electrophysiological recordings from smooth muscle, during fluid propulsion. Recordings showed pulsatile firing of excitatory and inhibitory neuromuscular inputs not only in proximal colon, but also distal colon, long before the propagating contraction invades the distal region. During propulsion, wavelet analysis revealed increased coherence at ~2 Hz over large distances between the proximal and distal regions. Therefore, during propulsion, synchronous firing of descending inhibitory nerve pathways over long ranges aborally acts to suppress smooth muscle from contracting, counteracting the excitatory nerve pathways over this same region of colon. This delays muscle contraction downstream, ahead of the advancing contraction. The mechanism identified is more complex than expected and vastly different from fluid propulsion along other hollow smooth muscle organs; like lymphatic vessels, portal vein, or ureters, that evolved without intrinsic neurons.[¶ added. - R]
QuoteBrain organoid with optic cups at day 60 of development.Image credit: Gabriel et al., Cell Stem CellMini brains grown in a lab from stem cells have spontaneously developed rudimentary eye structures, scientists report in a fascinating new paper.On tiny, human-derived brain organoids grown in dishes, two bilaterally symmetrical optic cups were seen to grow, mirroring the development of eye structures in human embryos. This incredible result will help us to better understand the process of eye differentiation and development, as well as eye diseases."Our work highlights the remarkable ability of brain organoids to generate primitive sensory structures that are light sensitive and harbor cell types similar to those found in the body," said neuroscientist Jay Gopalakrishnan of University Hospital Düsseldorf in Germany."These organoids can help to study brain-eye interactions during embryo development, model congenital retinal disorders, and generate patient-specific retinal cell types for personalized drug testing and transplantation therapies."[Continues . . .]
Quote from: Dark Lightning on August 27, 2021, 05:36:42 PM Googly eyes on the brain? Where's Silver!?