Links for Keyword: Consciousness
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by Linda Geddes Anaesthetics usually knock you out like a light. But by slowing the process down so that it takes 45 minutes to become totally unresponsive, researchers have discovered a new signature for unconsciousness. The discovery could lead to more personalised methods for administering anaesthetics and cut the risks associated with being given too high or too low a dose. It also sheds new light on what happens to our brain when we go under the knife. Hundreds of thousands of people are anaesthetised every day, yet researchers still don't fully understand what's going on in the anaesthetised brain. Nor is there a direct way of measuring when someone is truly unresponsive. Instead, anaesthetists rely on indirect measures such as heart and breathing rate, and monitoring reflexes. To investigate further, Irene Tracey and her colleagues at Oxford University slowed the anaesthesia process down. Instead of injecting the anaesthetic propofol in one go, which triggers unconsciousness in seconds, the drug was administered gradually so that it took 45 minutes for 16 volunteers to become fully anaesthetised. Their brain activity was monitored throughout using electroencephalography (EEG). The study was then repeated on 12 of these volunteers using functional magnetic resonance imaging (fMRI). EEG recordings revealed that before the volunteers became completely unresponsive to external stimuli they progressed through a sleep-like state characterised by slow-wave oscillations – a hallmark of normal sleep, in which neurons cycle between activity and inactivity. As the dose of anaesthetic built up, more and more neurons fell into this pattern, until a plateau was reached when no more neurons were recruited, regardless of the dose administered. © Copyright Reed Business Information Ltd.
Related chapters from BP7e: Chapter 18: Attention and Higher Cognition; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 14: Attention and Consciousness; Chapter 10: Biological Rhythms and Sleep
Link ID: 18836 - Posted: 10.26.2013
by Nora Schultz A SIMPLE bedside scan could reveal an active mind hidden inside an unresponsive body. The method provides another tool for recognising consciousness in people who have been wrongly diagnosed as being in a vegetative state. Tests are also under way to use it to monitor people under general anaesthetic, to make sure they do not regain consciousness during an operation. The technique builds on recent research into the nature of consciousness. "Information that is processed consciously typically recruits several brain regions at once," says Jean-Rémi King at the Brain and Spine Institute (ICM) in Paris, France. Other information that enters the brain triggers unconscious activity – for instance, the righting reflex that helps us retain balance when we are pushed – and it only tends to activate one brain area. King and his colleague Jacobo Sitt, also at the ICM, reasoned that they could spot consciousness in people simply by playing them a series of beeps and then searching electroencephalogram (EEG) brain scan data for evidence that signals from different brain regions fluctuated in the same way as each other, suggesting that they were sharing information. They performed their tests on 75 people in a vegetative state, 67 minimally conscious people, 24 people who had recently regained consciousness after a coma, and 14 healthy controls. By running the EEG data through statistics software, the researchers found differences between the patterns from people who were fully conscious, those in a vegetative state, and those who were minimally conscious (Current Biology, doi.org/n42). © Copyright Reed Business Information Ltd.
By Roy F. Baumeister It has become fashionable to say that people have no free will. Many scientists cannot imagine how the idea of free will could be reconciled with the laws of physics and chemistry. Brain researchers say that the brain is just a bunch of nerve cells that fire as a direct result of chemical and electrical events, with no room for free will. Others note that people are unaware of some causes of their behavior, such as unconscious cues or genetic predispositions, and extrapolate to suggest that all behavior may be caused that way, so that conscious choosing is an illusion. Scientists take delight in (and advance their careers by) claiming to have disproved conventional wisdom, and so bashing free will is appealing. But their statements against free will can be misleading and are sometimes downright mistaken, as several thoughtful critics have pointed out. Arguments about free will are mostly semantic arguments about definitions. Most experts who deny free will are arguing against peculiar, unscientific versions of the idea, such as that “free will” means that causality is not involved. As my longtime friend and colleague John Bargh put it once in a debate, “Free will means freedom from causation.” Other scientists who argue against free will say that it means that a soul or other supernatural entity causes behavior, and not surprisingly they consider such explanations unscientific. These arguments leave untouched the meaning of free will that most people understand, which is consciously making choices about what to do in the absence of external coercion, and accepting responsibility for one’s actions. Hardly anyone denies that people engage in logical reasoning and self-control to make choices. There is a genuine psychological reality behind the idea of free will. The debate is merely about whether this reality deserves to be called free will. Setting aside the semantic debate, let’s try to understand what that underlying reality is. © 2013 The Slate Group, LLC.
Joseph Brean U.S. President Barack Obama’s much-hyped BRAIN initiative to crack the mysteries of consciousness via a finely detailed map of the brain in action took its first big step this week, with the release of a strategy report that foresees “revolutionary advances” in the $100-million effort to “crack the brain’s code,” perhaps in as little as “a few years.” “We stand on the verge of a great journey into the unknown,” the report says, explicitly comparing BRAIN to the Apollo moon shot, and predicting it will “change human society forever.” As a grand challenge, Apollo was an unambiguous success, despite the vast expense and human costs, but there is a growing sense among scientists, if not legacy-minded politicians, that the road ahead for modern neuroscience will be pocked with disappointment, with more impenetrable mysteries than solvable problems. As the world approaches what some are calling “peak neuro,” after three decades of over-hyped “brain porn,” the optimistic hope is that Mr. Obama’s BRAIN project will lead to a detailed and dynamic map of the brain, and thus reveal both how it works and how it fails in such diseases as Alzheimer’s or autism. The pessimistic fear, however, is that the “speed of thought,” as Mr. Obama described it, is just too quick for our current brain imaging technologies, primarily functional magnetic resonance imaging (fMRI). As the anonymous blogger Neuroskeptic, a British brain scientist who tracks the misinterpretation of brain scan studies by both scientists and media, put it in an email, “there’s just as much hype and misrepresentation as ever.” The more we learn about the brain, the less we seem to know. With its potential overstated and its aspirations presented as foregone conclusions, the relatively new field of neuroscience is in a period of self-reflection, said Jackie Sullivan, a philosopher of neuroscience at Western University in London Ont. “The vast majority of neuroscientists are well aware that the goals going forward need to be more modest,” she said. © 2013 National Post
Related chapters from BP7e: Chapter 18: Attention and Higher Cognition; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 14: Attention and Consciousness; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 18686 - Posted: 09.23.2013
by Andy Coghlan Parts of the brain may still be alive after a person's brain activity is said to have flatlined. When someone is in a deep coma, their brain activity can go silent. An electroencephalogram measuring this activity may eventually show a flatline, usually taken as a sign of brain death. However, while monitoring a patient who had been placed in a deep coma to prevent seizures following a cardiac arrest, Bogdan Florea, a physician at the Regina Maria Medical Centre in Cluj-Napoca, Romania, noticed a strange thing – some tiny intermittent bursts of activity were interrupting an otherwise flatline signal, each lasting a few seconds. He asked Florin Amzica of the University of Montreal in Canada and his colleagues to investigate what might be happening. To imitate what happened in the patient, Amzica's team put cats into a deep coma using a high dose of anaesthesia. While EEG recordings taken from the surface of the brain – the cortex – showed a flatline, recordings from deep-brain electrodes revealed tiny bursts of activity originating in the hippocampus, responsible for memory and learning, which spread within minutes to the cortex. "These ripples build up a synchrony that rises in a crescendo to reach a threshold where they can spread beyond the hippocampus and trigger activity in the cortex," says Amzica. © Copyright Reed Business Information Ltd.
Related chapters from BP7e: Chapter 18: Attention and Higher Cognition; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 14: Attention and Consciousness; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 18683 - Posted: 09.21.2013
by Sara Reardon It can be nearly impossible to know what is happening in the mind of someone who has experienced a severe brain injury, but two new methods could offer some clues. Together, they provide not only a better indication of consciousness but also a more effective way to communicate with some vegetative people. The way that a seemingly unconscious person behaves does not always reflect their mental state. Someone in a completely vegetative state may still be able to smile simply through reflex, while a perfectly alert person may be left unable to do so if a brain injury has affected their ability to move. So a different way to assess mental state is needed. Marcello Massimini at the University of Milan in Italy and his colleagues have developed a possible solution by stimulating brains with an electromagnetic pulse and then measuring the response. The pulse acts like striking a bell, they say, and neurons across the entire brain continue to "ring" in a specific wave pattern, depending on how active the connections between individual brain cells are. The team used this method to assess 20 people with brain injuries who were either in a vegetative state, in a minimally conscious state, or in the process of emerging from a coma. The team compared the patterns from these people with the patterns recorded from 32 healthy people who were awake, asleep or under anaesthesia. In each of the distinct states of consciousness, the researchers found, the neurons "shook" in a distinctive pattern in response to the electromagnetic pulse. © Copyright Reed Business Information Ltd
Kelly Servick Consciousness isn’t easy to define, but we know it when we experience it. It’s not so simple to decide when someone else is conscious, however, as doctors must sometimes do with patients who have suffered traumatic brain injury. Now, researchers have come up with an approach that uses the brain’s response to magnetic stimulation to judge a person’s awareness, reducing it to a numerical score they call an index of consciousness. “You’re kind of banging on the brain and listening to the echo,” says Anil Seth, a neuroscientist at the Sackler Centre for Consciousness Science at the University of Sussex in the United Kingdom who was not involved in the work. Faced with an unresponsive patient, clinicians do their best to determine whether the person is conscious. Through sound, touch, and other stimuli, they try to provoke verbal responses, slight finger movements, or just a shifting gaze. Yet some conscious patients simply can’t move or speak; an estimated 40% of those initially judged to be completely unaware are later found to have some level of consciousness. Recently, physicians seeking to resolve a patient’s conscious state have gone right to the source, searching for signs of awareness using brain imaging or recording electrical activity of neurons. Most of these approaches define a conscious brain as an integrated brain, where groups of cells in many different regions activate to form a cohesive pattern, explains Marcello Massimini, a neurophysiologist at the University of Milan in Italy. “But that’s not enough,” he says. Sometimes even an unconscious brain looks highly integrated. For example, stimulating the brain of a sleeping person can create a huge wave of activity that “propagates like a ripple in water.” It’s a highly synchronized, widespread pattern, but it’s not consciousness, he says, and so this measure is often unreliable for diagnosis. © 2012 American Association for the Advancement of Science.
By Gary Stix Unraveling the mystery of consciousness remains perhaps the biggest challenge in all neuroscience, so big and amorphous that most brain scientists won’t go near the topic, leaving philosophers to speculate about the a prioris. Even defining what consciousness is quickly devolves into lengthy and often ponderous treatises. The World Science Festival assembled a panel of luminaries who will attempt to make sense of this sprawling theme in the allotted 90 minutes. They included Mélanie Boly, a researcher and physician who has performed studies on minimally conscious patients; Christof Koch, a leading researcher on the neural basis of consciousness; Colin McGinn, known for his work on the philosophy of mind, and Nicholas Schiff, a physician-scientist who specializes in disorders of consciousness. Click below here to see these leading lights gathered at NYU’s Skirball Center for the Performing Arts on May 30 to take on whether Homo sapiens is the only conscious species, the question of whether consciousness transcends the physical boundaries of the brain, and an exploration of the biochemical processes that underlie the life of the mind. The session, entitled “The Whispering Mind: The Enduring Conundrum of Consciousness,” is moderated by ABC Nightline co-anchor Terry Moran. © 2013 Scientific American
Posted by Gary Marcus A few weeks ago, while staying with my in-laws, my four-month-old son woke up at two-thirty in the morning. He was hungry, and, knowing that he would not be coaxed back to sleep without a bottle, I brought him downstairs to the kitchen, where his crying stopped abruptly. He clearly recognized that he had arrived in an unfamiliar place, and he became fully absorbed in understanding where he was and how he’d gotten there. He was searingly alert; he craned his head and his eyes darted around. The eight minutes or so that it took it to warm the bottle, usually a time of intense complaint, passed with hardly a peep. I became convinced that, for the first time, my son was fully, consciously aware of his surroundings. As a scientist, I realize that my experience was subjective. But the leading scientific journal, Science, just published the results of an experiment that endeavored to look objectively at the rudiments of consciousness in infants. This work, conducted by the cognitive psychologists Sid Kouider, Stanislas Dehaene, and Ghislaine Dehaene-Lambertz, is an examination of brain waves in babies between five and fifteen months old, aimed at constructing what the scientists refer to as a “biological signature of consciousness.” The background of this experiment is a theory called the “global workspace” model of consciousness, according to which perceptual awareness involves two stages of neural activity. The first is a purely sensory activation, typically in the back of the brain. The second stage reflects a kind of “ignition,” and is achieved only for stimuli that are consciously perceived. © 2013 Condé Nast.
Related chapters from BP7e: Chapter 18: Attention and Higher Cognition; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 14: Attention and Consciousness; Chapter 13: Memory, Learning, and Development
Link ID: 18209 - Posted: 05.30.2013
By Ferris Jabr On any given day, millions of conversations reverberate through New York City. Poke your head out a window overlooking a busy street and you will hear them: all those overlapping sentences, only half-intelligible, forming a dense acoustic mesh through which escapes an exclamation, a buoyant laugh, a child’s shrill cry now and then. Every spoken consonant and vowel begins as an internal impulse. Electrical signals crackle along branching neurons in brain regions specialized for language and movement; further pulses spread across facial nerves, surge toward the throat and chest and zip down the spine. The diaphragm contracts—pulling air into the lungs—and relaxes, pushing air into that birdcage of calcium and cartilage—the larynx—within which wings of tissue draw near one another and hum. As this vibrating air enters the mouth, the tongue guides its flow and the lips give each breath a final shape and sound. Liberated syllables travel between one person and another in waves of colliding air molecules. All these conversations are matched in number and complexity by much more elusive discourses. The human brain loves soliloquy. Even when speaking with others—and especially when alone—we continually talk to ourselves in our heads. Such speech does not require the bellows in the chest, quivering flaps of tissue in the throat or a nimble tongue; it does not need to disturb even one hair cell in our ears, nor a single particle of air. We can speak to ourselves without making a sound. Stick your head out that same window above the crowded street and you will hear nothing of what people are saying to themselves privately. All that inner dialogue remains submerged beneath the ocean of human speech, like a novel written in invisible ink behind the text of another book. © 2013 Scientific American,
by Caroline Williams When it comes to making decisions, it seems that the conscious mind is the last to know. We already had evidence that it is possible to detect brain activity associated with movement before someone is aware of making a decision to move. Work presented this week at the British Neuroscience Association (BNA) conference in London not only extends it to abstract decisions, but suggests that it might even be possible to pre-emptively reverse a decision before a person realises they've made it. In 2011, Gabriel Kreiman of Harvard University measured the activity of individual neurons in 12 people with epilepsy, using electrodes already implanted into their brain to help identify the source of their seizures. The volunteers took part in the "Libet" experiment, in which they press a button whenever they like and remember the position of a second hand on a clock at the moment of decision. Kreiman discovered that electrical activity in the supplementary motor area, involved in initiating movement, and in the anterior cingulate cortex, which controls attention and motivation, appeared up to 5 seconds before a volunteer was aware of deciding to press the button (Neuron, doi.org/btkcpz). This backed up earlier fMRI studies by John-Dylan Haynes of the Bernstein Center for Computational Neuroscience in Berlin, Germany, that had traced the origins of decisions to the prefrontal cortex a whopping 10 seconds before awareness (Nature Neuroscience, doi.org/cs3rzv). "It's always nice when two lines of research converge and to know that what we see with fMRI is actually there in the neurons," says Haynes. © Copyright Reed Business Information Ltd.
Kerri Smith The experiment helped to change John-Dylan Haynes's outlook on life. In 2007, Haynes, a neuroscientist at the Bernstein Center for Computational Neuroscience in Berlin, put people into a brain scanner in which a display screen flashed a succession of random letters1. He told them to press a button with either their right or left index fingers whenever they felt the urge, and to remember the letter that was showing on the screen when they made the decision. The experiment used functional magnetic resonance imaging (fMRI) to reveal brain activity in real time as the volunteers chose to use their right or left hands. The results were quite a surprise. "The first thought we had was 'we have to check if this is real'," says Haynes. "We came up with more sanity checks than I've ever seen in any other study before." The conscious decision to push the button was made about a second before the actual act, but the team discovered that a pattern of brain activity seemed to predict that decision by as many as seven seconds. Long before the subjects were even aware of making a choice, it seems, their brains had already decided. As humans, we like to think that our decisions are under our conscious control — that we have free will. Philosophers have debated that concept for centuries, and now Haynes and other experimental neuroscientists are raising a new challenge. They argue that consciousness of a decision may be a mere biochemical afterthought, with no influence whatsoever on a person's actions. According to this logic, they say, free will is an illusion. "We feel we choose, but we don't," says Patrick Haggard, a neuroscientist at University College London. © 2013 Nature Publishing Group
by Julia Sklar IT IS a nightmare situation. A person diagnosed as being in a vegetative state has an operation without anaesthetic because they cannot feel pain. Except, maybe they can. Alexandra Markl at the Schön clinic in Bad Aibling, Germany, and colleagues studied people with unresponsive wakefulness syndrome (UWS) – also known as vegetative state – and identified activity in brain areas involved in the emotional aspects of pain. People with UWS can make reflex movements but can't show subjective awareness. There are two distinct neural networks that work together to create the sensation of pain. The more basic of the two – the sensory-discriminative network – identifies the presence of an unpleasant stimulus. It is the affective network that attaches emotions and subjective feelings to the experience. Crucially, without the activity of the emotional network, your brain detects pain but won't interpret it as unpleasant. Using PET scans, previous studies have detected activation in the sensory-discriminative network in people with UWS but their findings were consistent with a lack of subjective awareness, the hallmark of the condition. Now Markl and her colleagues have found evidence of activation in the affective or emotional network too (Brain and Behavior, doi.org/kfs). © Copyright Reed Business Information Ltd.
Related chapters from BP7e: Chapter 18: Attention and Higher Cognition; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 14: Attention and Consciousness; Chapter 5: The Sensorimotor System
Link ID: 17839 - Posted: 02.23.2013
By Mark Fischetti Various scholars have tried to explain consciousness in long articles and books, but one neuroscience pioneer has just released an unusual video blog to get the point across. In the sharply filmed and edited production, Joseph LeDoux, a renowned expert on the emotional brain at New York University, interrogates his NYU colleague Ned Block on the nature of consciousness. Block is a professor of philosophy, psychology and neural science and is considered a leading thinker on the subject. The interview ends with a transition into a music video performed by LeDoux’s longstanding band, the Amygdaloids. The whole exercise is a bit quirky, yet it succeeds in explaining consciousness in simple, even entertaining terms. LeDoux intends to produce a series of these video blogs to explore other intriguing aspects of the mind and brain, and he is giving Scientific American the chance to post them first on our Web site. LeDoux has already interviewed Michael Gazzaniga at the University of California, Santa Barbara, on free will and Nobel Prize winner Eric Kandel at Columbia University on mapping the mind. The video is not a quick hit, like most on the Net these days. The interview runs about 10 minutes, followed by the four-minute music video. The idea is for viewers to sit back and actually think along with the expert as his or her explanation unfolds. Yet video producer Alexis Gambis has generated some compelling imagery to keep our visual attention as Block unwraps his subject. Gambis directs the Imagine Science Film Festival, is about to complete his graduate degree in film and has a doctorate in molecular biology. © 2013 Scientific American
By ISABEL KERSHNER JERUSALEM — A brain scan performed on Ariel Sharon, the former Israeli prime minister who had a devastating stroke seven years ago and is presumed to be in a vegetative state, revealed significant brain activity in response to external stimuli, raising the chances that he is able to hear and understand, a scientist involved in the test said Sunday. Scientists showed Mr. Sharon, 84, pictures of his family, had him listen to a recording of the voice of one of his sons and used tactile stimulation to assess the extent of his brain’s response. “We were surprised that there was activity in the proper parts of the brain,” said Prof. Alon Friedman, a neuroscientist at Ben-Gurion University of the Negev and a member of the team that carried out the test. “It raises the chances that he hears and understands, but we cannot be sure. The test did not prove that.” The activity in specific regions of the brain indicated appropriate processing of the stimulations, according to a statement from Ben-Gurion University, but additional tests to assess Mr. Sharon’s level of consciousness were less conclusive. “While there were some encouraging signs, these were subtle and not as strong,” the statement added. The test was carried out last week at the Soroka University Medical Center in the southern Israeli city of Beersheba using a state-of-the-art M.R.I. machine and methods recently developed by Prof. Martin M. Monti of the University of California, Los Angeles. Professor Monti took part in the test, which lasted approximately two hours. © 2013 The New York Times Company
Doctors should resist the temptation to use an inexpensive tool that probes the brain's electrical activity when evaluating vegetative patients who can't communicate. Drs. Adrian Owen and Damian Cruse of the Centre for Brain and Mind in London, Ont., promoted the use of electroencephalography or EEG that can be used at a patient's bedside to determine if there's neurological activity in people in a vegetative state — those who are unresponsive in traditional tests of awareness. In a letter published in Thursday's issue of the medical journal The Lancet, Dr. Jonathan Victor of Weill Cornell Medical College in New York and his co-authors reanalyzed data shared from Owen's 2011 paper in the same journal. "I think we'd be very, very cautious about using this technology as it stands now," said Victor. Both groups agree the use of EEG technology remains promising to evaluate patients. The challenge, Victor said, is researchers can't be certain about their interpretations when faced with families trying to communicate with their loved ones, including for end-of-life discussions. The critique casts doubt on the original statistical approach and assumptions, which didn't hold when analyzed with a different model. In a rebuttal, Owen's team defended its approach as the only way to draw valid conclusions from vegetative patients and account for their variations. "There are few 'known truths' when attempting to detect covert awareness," Owen's team wrote. "Some are likely to be truly vegetative, while others may appear to be vegetative behaviorally, but are in fact, covertly aware." © CBC 2013
By John Horgan We’re approaching the end of one year and the beginning of another, when people resolve to quit smoking, swill less booze, gobble less ice cream, jog every day, or every other day, work harder, or less hard, be nicer to kids, spouses, ex-spouses, co-workers, read more books, watch less TV, except Homeland, which is awesome. In other words, it’s a time when people seek to alter their life trajectories by exercising their free will. Some mean-spirited materialists deny that free will exists, and this specious claim—not mere physiological processes in my brain–motivates me to reprint a defense of free will that I wrote for The New York Times 10 years ago: When I woke this morning, I stared at the ceiling above my bed and wondered: To what extent will my rising really be an exercise of my free will? Let’s say I got up right . . . now. Would my subjective decision be the cause? Or would computations unfolding in a subconscious neural netherworld actually set off the muscular twitches that slide me out of the bed, quietly, so as not to wake my wife (not a morning person), and propel me toward the door? One of the risks of science journalism is that occasionally you encounter research that threatens something you cherish. Free will is something I cherish. I can live with the idea of science killing off God. But free will? That’s going too far. And yet a couple of books I’ve been reading lately have left me brooding over the possibility that free will is as much a myth as divine justice. © 2012 Scientific American
By Ferris Jabr The computer, smartphone or other electronic device on which you may be reading this article, tracking the weather or checking your e-mail has a kind of rudimentary brain. It has highly organized electrical circuits that store information and behave in specific, predictable ways, just like the interconnected cells in your brain. On the most fundamental level, electrical circuits and neurons are made of the same stuff—atoms and their constituent elementary particles—but whereas the human brain is conscious of itself, man-made gadgets do not know they exist. Consciousness, most scientists would argue, is not a shared property of all matter in the universe. Rather consciousness is restricted to a subset of animals with relatively complex brains. The more scientists study animal behavior and brain anatomy, however, the more universal consciousness seems to be. A brain as complex as a human's is definitely not necessary for consciousness. On July 7 of this year, a group of neuroscientists convening at the University of Cambridge signed a document entitled “The Cambridge Declaration on Consciousness in Non-Human Animals,” officially declaring that nonhuman animals, “including all mammals and birds, and many other creatures, including octopuses,” are conscious. Humans are more than just conscious; they are also self-aware. Scientists differ on how they distinguish between consciousness and self-awareness, but here is one common distinction: consciousness is awareness of your body and your environment; self-awareness is recognition of that consciousness—not only understanding that you exist but further comprehending that you are aware of your existence. Another way of considering it: to be conscious is to think; to be self-aware is to realize that you are a thinking being and to think about your thoughts. Presumably human infants are conscious—they perceive and respond to people and things around them—but they are not yet self-aware. In their first years of life, children develop a sense of self, learning to recognize themselves in the mirror and to distinguish between their own point of view and the perspectives of other people. © 2012 Scientific American,
By Tanya Lewis A coma patient’s chances of surviving and waking up could be predicted by changes in the brain’s ability to discriminate sounds, new research suggests. Recovery from coma has been linked to auditory function before, but it wasn’t clear whether function depended on the time of assessment. Whereas previous studies tested patients several days or weeks after comas set in, a new study looks at the critical phase during the first 48 hours. At early stages, comatose brains can still distinguish between different sound patterns,. How this ability progresses over time can predict whether a coma patient will survive and ultimately awaken, researchers report. “It’s a very promising tool for prognosis,” says neurologist Mélanie Boly of the Belgian National Fund for Scientific Research, who was not involved with the study. “For the family, it’s very important to know if someone will recover or not.” A team led by neuroscientist Marzia De Lucia of the University of Lausanne in Switzerland studied 30 coma patients who had experienced heart attacks that deprived their brains of oxygen. All the patients underwent therapeutic hypothermia, a standard treatment to minimize brain damage, in which their bodies were cooled to 33° Celsius for 24 hours. De Lucia and colleagues played sounds for the patients and recorded their brain activity using scalp electrodes — once in hypothermic conditions during the first 24 hours of coma, and again a day later at normal body temperature. The sounds were a series of pure tones interspersed with sounds of different pitch, duration or location. The brain signals revealed how well patients could discriminate the sounds, compared with five healthy subjects. © Society for Science & the Public 2000 - 2012
Related chapters from BP7e: Chapter 18: Attention and Higher Cognition; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 14: Attention and Consciousness; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17546 - Posted: 11.27.2012
By Courtney Humphries A. Fainting, also called syncope, is a sudden and brief loss of consciousness followed by a spontaneous return to wakefulness — people who “black out” and then “come to” on their own without outside intervention. During the faint, they’re in danger of falls and injuries if they lose muscle control. There are several possible causes of fainting, but they all stem from a temporary decrease in blood flow to the brain. The typical Victorian-era swoon is one of the most common forms, called vasovagal syncope. Lewis Lipsitz, a geriatrician at Beth Israel Deaconess Medical Center and Hebrew SeniorLife, explains that it’s caused by a reflexive response to a stimulus, such as stress, a sudden shock, or the sight of blood. Fainting without an obvious trigger can be a sign of an underlying health problem, such as an irregular heart rhythm, heart disease, or severe dehydration. “The elderly have syncope more commonly than any other group,” Lipsitz says, which can put them at risk of falls and fractures. Often the spells are caused by actions as simple as changing position or eating a meal. When we stand up, Lipsitz says, “about half a liter of blood immediately goes to the legs and the lower abdomen,” and eating also pulls blood from the brain to the gut. Our bodies compensate by raising the heart rate to get blood to the brain. But elderly people can’t always restore their blood flow, and dehydration or certain medications can exacerbate the problem. © Copyright 2012 Globe Newspaper Company.