Posts Tagged neuroscience

[BOOK] Neuroscience – E-Book: Fundamentals for Rehabilitation – Laurie Lundy-Ekman – Google Books

 

Neuroscience – E-BookFundamentals for Rehabilitation

Front Cover
Elsevier Health SciencesOct 30, 2017 – 576 pages

Boost your skills in planning and managing physical rehabilitation! Neuroscience: Fundamentals for Rehabilitation,5th Edition provides a practical guide to the nervous system and how it affects the practice of physical and occupational therapy. Case studies and first-person stories from people with neurologic disorders make it easier to apply your knowledge to the clinical setting. New to this edition are new chapters on neuroanatomy imaging and neurologic examination techniques. Written by noted PT educator Laurie Lundy-Ekman, this book uses evidence-based research to help you understand neurologic disorders and treat clients who have physical limitations due to nervous system damage or disease.

 

  • Logical, systems approach to neuroscience makes it easier to master complex information and provides a framework for conducting a neurologic examination and evaluation.
  • A clinical perspective of neuroscience is provided through case studies, personal stories written by patients, and summaries of key features of neurologic disorders and the body systems they affect.
  • Five sections — Overview of Neurology, Neuroscience at the Cellular Level, Development of the Nervous System, Vertical Systems, and Regions — first show how neural cells operate, and then allow you to apply your knowledge of neuroscience.
  • Emphasis on topics critical to physical rehabilitation includes coverage of abnormal muscle tone, chronic pain, control of movement, and differential diagnosis of dizziness.
  • Hundreds of color-coded illustrations show body structures and functions across systems.
  • Clinical Notes case studies demonstrate how neuroscience knowledge may be applied to clinical situations.
  • Pathology boxes provide a quick summary of the features of neurologic disorders commonly encountered in rehabilitation practice.

 

  • New! Neuroimaging and Neuroanatomy Atlaschapter includes MRI and CT images.
  • NEW!Neurologic Disorders and the Neurologic Examinationchapter provides detailed descriptions and photographs of techniques.
  • NEW! Diagnostic Clinical Reasoning boxes help you develop the ability to recognize patterns of signs and symptoms associated with specific diagnoses.
  • NEW! Updated content reflects the most current research findings.
  • NEW! Reader-friendly approach converts long, technical chapters into smaller, more accessible chapters.
  • NEW! Reorganized chapters progress from the cellular view to the systems view to the regional view.

Preview this book »

 

via Neuroscience – E-Book: Fundamentals for Rehabilitation – Laurie Lundy-Ekman – Google Books

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[WEB SITE] Findings reveal how seizures can have lasting detrimental effects on memory

October 16, 2017

Although it’s been clear that seizures are linked to memory loss and other cognitive deficits in patients with Alzheimer’s disease, how this happens has been puzzling. In a study published in the journal Nature Medicine, a team of researchers reveals a mechanism that can explain how even relatively infrequent seizures can lead to long-lasting cognitive deficits in animal models. A better understanding of this new mechanism may lead to future strategies to reduce cognitive deficits in Alzheimer’s disease and other conditions associated with seizures, such as epilepsy.

“It’s been hard to reconcile how infrequent seizures can lead to persistent changes in memory in patients with Alzheimer’s disease,” said corresponding author Dr. Jeannie Chin, assistant professor of neuroscience at Baylor College of Medicine. “To solve this puzzle, we worked with a mouse model of Alzheimer’s disease focusing on the genetic changes that seizures might trigger in the memory center of the brain, the hippocampus, that could lead to loss of memory or other cognitive deficits.”

The researchers measured the levels of a number of proteins involved in memory and learning and found that levels of the protein deltaFosB strikingly increase in the hippocampus of Alzheimer’s disease mice that had seizures. DeltaFosB already is well known for its association with other neurological conditions linked to persistent brain activity of specific brain regions, such as addiction. In this study, the researchers found that after a seizure, the deltaFosB protein remains in the hippocampus for an unusually long time; its half-life – the time it takes for the amount of protein to decrease by half – is eight days. Most proteins have a half-life that is between hours and a day or two.

“Interestingly, because deltaFosB is a transcription factor, meaning that its job is to regulate the expression of other proteins, these findings led us to predict that the increased deltaFosB levels might be responsible for suppressing the production of proteins that are necessary for learning and memory,” Chin said. “In fact, we found that when the levels of deltaFosB increase, those of other proteins, such as calbindin, decrease. Calbindin also has been known for a long time to be involved in Alzheimer’s disease and epilepsy, but its mechanism of regulation was not known. We then hypothesized that deltaFosB might be regulating the production of calbindin.”

Further investigations supported the researchers’ hypothesis. The scientists showed that deltaFosB can bind to the gene calbindin suppressing the expression of the protein. When they either prevented deltaFosB activity or experimentally increased calbindin expression in the mice, calbindin levels were restored and the mice improved their memory. And when researchers experimentally increased deltaFosB levels in normal mice, calbindin expression was suppressed and the animals’ memory deteriorated, demonstrating that deltaFosB and calbindin are key regulators of memory.

Connecting pieces of the puzzle

“Our findings have helped us answer the question of how even infrequent seizures can have such lasting detrimental effects on memory,” Chin said. “We found that seizures can increase the levels of deltaFosB in the hippocampus, which results in a decrease in the levels of calbindin, a regulator of memory processes. DeltaFosB has a relatively long half-life, therefore even when seizures are infrequent, deltaFosB remains in the hippocampus for weeks acting like a brake, reducing the production of calbindin and other proteins, and disrupting the consequent brain activity involved in memory. The regulation of gene expression far outlasts the actual seizure event that triggered it.”

The scientists found the same changes in deltaFosB and calbindin levels in the hippocampus of Alzheimer’s disease patients and in the temporal lobe of epilepsy patients. However, they underscore that it is too soon to know whether regulating deltaFosB or calbindin could improve or prevent memory problems or other cognitive deficits in people with Alzheimer’s disease. However, “now that we know that the levels of deltaFosB and calbindin are effective markers of brain activity in the hippocampus and memory function, we propose that these markers could potentially help assess clinical therapies for Alzheimer’s and other diseases with seizures,” Chin said.

Source: Findings reveal how seizures can have lasting detrimental effects on memory

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[WEB SITE] How neuroscience can pave the way for VR’s

For Noah Falstein, the future of virtual reality depends not only on understanding the technology and the market, but understanding the fundamental underpinnings of the human brain.

“It’s like you’re going through a mountain pass,” he said at VRDC Fall 2017 in San Francisco today, speaking to an audience made up of game developers as well as people in other industries. Right now, VR is still new territory, and on the other side of that mountain pass, a fertile valley might open up, or maybe not. “Along the way, it’s easy to get stuck,” he said.

But Falstein, who is a true believer in the future of VR, AR, and MR, says that neuroscience is the compass to point this new technology in the correct direction.

A history of conveying images

Falstein is a true veteran of game development, working at companies including Williams Electronics and LucasArts, and most recently was chief game designer at Google. He now runs his own design consultancy company, The Inspiracy.

Falstein briefly went over humankind’s quest to share images, using the example of a 20,000-year-old cave painting. “Our ancestors have been struggling with this for a long time,” he said—the desire to convey something one might personally see to other people. From cave paintings to camcorders, to smartphones with advanced cameras, to VR today, humans have been trying all kinds of ways to convey images that inform or evoke emotions in other people.

Falstein’s approach to understanding the uses and applications of immersive computing lies in trying to understand how the brain itself works and how it has evolved.

Motion

“One of the first things that comes up in VR is the potential of motion sickness,” Falstein said. “I think we’re always going to have some people at the end of that spectrum who just have trouble in VR when they move too swiftly,” he said, but there are some ways to minimize motion sickness.

Falstein explained how motion sickness is evolutionary—when a person is poisoned, it disrupts the inner ear, creating a disconnect between actual movement and the movement one feels in their head. This leads to nausea, which is a great way to throw up and purge a poison mushroom or food that has turned.

He acknowledged that there’s always a person in the studio who’s the most susceptible to motion sickness who is used as the motion sickness guinea pig. “I frankly don’t think we’ll have a better [motion sickness testing] system than that for some time to come,” he said.

He stated some well-known (among VR game devs) facts about preventing VR motion sickness: you need a fast frame rate (90+ is best); devs must minimize lag when the head moves (20ms or less); they should get all visual cues right; minimize acceleration; and come up with creative anti-sickness solutions based on how our visual field and vestibular system interact.

He also explained how blurring or eliminating peripheral vision during acceleration can help fight motion sickness. Some games and Google Earth in VR use this method, and as eye tracking systems become more advanced, users will have more comfortable VR experiences, he said.

Emotion

“It turns out that VR is really good at scaring people,” he said. Movie directors figured this out fairly early in film, and VR developers have found this out too.

“Why is horror in VR so strong?” Falstein explained how the human brain—particularly the amygdala—does the quick, raw processing of fear, anger, and aggression (fight of flight), and also arousal and intimacy.

“In video games, we’re really good at the fight or flight stuff, but the intimacy and empathy stuff, we’re still working on that,” he said.

But with VR, as it “tricks” more of your senses, there’s opportunity for more intimacy and it also appeals stronger to empathy, he said.

Falstein also talked about the possibilities in storytelling when it comes to movies shown in VR, such as short stories in VR (like Google’s Spotlight Stories series), 180-degree movie viewing, or shared or single-viewer experiences. “There’s going to be strong ‘replay’ value for things they missed [on first view],” Falstein said. There are also opportunities for monetization through ads and product placement.

Beyond Emotion

Falstein briefly pointed out how games as medicine is a new market with massive opportunity, and VR can be part of this in treating issues like phobias, PTSD, acute pain, and strokes, as well as training doctors and caregivers.

“It’s really exciting stuff,” he said, “and the future is in your hands.”

Source: Gamasutra – How neuroscience can pave the way for VR’s

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[Review] The Neuroscience of Body Memory: from the Self through the Space to the Others – Full Text

Abstract

Our experience of the body is not direct; rather, it is mediated by perceptual information, influenced by internal information, and recalibrated through stored implicit and explicit body representation (body memory). This paper presents an overview of the current investigations related to body memory by bringing together recent studies from neuropsychology, neuroscience, and evolutionary and cognitive psychology. To do so, in the paper, we explore the origin of representations of human body to elucidate their developmental process and, in particular, their relationship with more explicit concepts of self. First, it is suggested that our bodily experience is constructed from early development through the continuous integration of sensory and cultural data from six different representations of the body, i.e., the Sentient Body (Minimal Selfhood), the Spatial Body (Self Location), the Active Body (Agency), the Personal Body (Whole Body Ownership – Me); the Objectified Body (Objectified Self – Mine), and the Social Body (Body Satisfaction – Ideal Me). Then, it is suggested that these six representations can be combined in a coherent supramodal representation, i.e. the “body matrix”, through a predictive, multisensory processing activated by central, top–down, attentional processes. From an evolutionary perspective, the main goal of the body matrix is to allow the self to protect and extend its boundaries at both the homeostatic and psychological levels. From one perspective, the self extends its boundaries (peripersonal space) through the enactment and recognition of motor schemas. From another perspective, the body matrix, by defining the boundaries of the body, also defines where the self is present, i.e., in the body that is processed by the body matrix as the most likely to be its one and in the space surrounding it. In the paper we also introduced and discusses the concept of “embodied medicine”: the use of advanced technology for altering the body matrix with the goal of improving our health and well-being.


1. Introduction

The body is an object of perception, just like any other object in the world. Yet, at the same time, the body is different (Aspell, Lenggenhager, & Blanke, 2012). From one perspective, it provides the background conditions that enable perception and action (cognitive approach); from another perspective, it is associated closely with our sense of self and its intentionality (volitional approach).

For these reasons, different researchers have identified the experience of the body as the possible starting point for the development of a comprehensive scientific model of self-consciousness (Ananthaswamy, 2015; Craig, 2009, 2010; Damasio, 2010; Lenggenhager, Tadi, Metzinger, & Blanke, 2007; Tsakiris, 2012, 2017).

However, to study the experience of the body is not an easy task. As noted by Olaf Blanke (2012), the body is the most multi-sensory “object” in the world; it requires the processing and integration of different bodily signals in the premotor, temporoparietal, posterior parietal, and extrastriate cortices. In addition, our experience of the body is not direct (Figure 1), but it is (Blanke, Slater, & Serino, 2015; Pazzaglia & Zantedeschi, 2016; Riva, […]

 

Continue —>  The Neuroscience of Body Memory: from the Self through the Space to the Others

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[Abstract] Constraint-Induced Movement Therapy for Chronic Hemiparesis: Neuroscience Evidence from Basic Laboratory Research and Quantitative Structural Brain MRI in Patients with Diverse Disabling Neurological Disorders (S43.003)

Abstract

Objective: This presentation will review the basic neuroscience research origins and the effects of Constraint-Induced Movement therapy (CIMT) on CNS structural neuroplasticity.

Background: Experimental hemiparesis in primates overcame chronic limb nonuse by applying specific behavioral neuroscience principles. This research led to formulating a model for the origination of sustained motor disability after neurological injury and its improvement by a novel therapeutic program. The therapy became adapted to treating children and adults and termed CIMT. Over the past 25 years multiple worldwide Randomized Controlled Trials of CIMT enrolled nearly 2000 patients with diverse neurological disorders (stroke, cerebral palsy [CP], multiple sclerosis [MS]), which indicated superiority of the approach against control therapies, with large treatment Effect Sizes and sustained retention of improved spontaneous real-world use of the hemiparetic limb. Ongoing research will describe basic and clinical neuroimaging methods to explore the basis for the clinical efficacy of CIMT.

Design/Methods: (1) Basic neuroscience models of experimental limb nonuse in rodents that had undergone adapted CIMT, which were followed by histological studies. (2) Voxel-based morphometry (VBM) of grey matter and Tract-based spatial statistics (TBSS) of white matter on structural brain MRI, which evaluated neuroplastic changes after upper extremity CIMT.

Results: (1) CIMT in rodents resulted in increased CNS axonal growth, synaptogenesis, and neurogenesis compared to control interventions, parallel with improved paretic limb use. (2) VBM demonstrated profuse cortical and subcortical grey matter increase following CIMT for stroke, CP, and MS. TBSS indicated significantly improved white matter integrity in MS. Neither structural brain changes nor comparable improved paretic limb use followed control interventions.

Conclusions: CIMT is increasing worldwide practice to improve reduced real-world limb use in chronic hemiparesis in diverse neurological diseases and ages of patients. Structural CNS changes following CIMT may support improved and extended functional use of the paretic limb.

Source: Constraint-Induced Movement Therapy for Chronic Hemiparesis: Neuroscience Evidence from Basic Laboratory Research and Quantitative Structural Brain MRI in Patients with Diverse Disabling Neurological Disorders (S43.003)

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[WEB SITE] UC study explores how low risk stress reduction treatments may benefit epilepsy patients

Patients with epilepsy face many challenges, but perhaps the most difficult of all is the unpredictability of seizure occurrence. One of the most commonly reported triggers for seizures is stress.

A recent review article in the European journal Seizure, by researchers at University of Cincinnati Epilepsy Center at the UC Gardner Neuroscience Institute, looks at the stress-seizure relationship and how adopting stress reduction techniques may provide benefit as a low risk form of treatment.

The relationship between stress and seizures has been well documented over the last 50 years. It has been noted that stress can not only increase seizure susceptibility and in rare cases a form of reflex epilepsy, but also increase the risk of the development of epilepsy, especially when stressors are severe, prolonged, or experienced early in life.

“Studies to date have looked at the relationship from many angles,” says Michael Privitera, MD, director of the UC Epilepsy Center and professor in the Department of Neurology and Rehabilitation Medicine at the UC College of Medicine. “The earliest studies from the 1980s were primarily diaries of patients who described experiencing more seizures on ‘high-stress days’ than on ‘low-stress days.'”

Privitera and Heather McKee, MD, an assistant professor in the Department of Neurology and Rehabilitation Medicine, looked at 21 studies from the 1980s to present–from patients who kept diaries of stress levels and correlation of seizure frequency, to tracking seizures after major life events, to fMRI studies that looked at responses to stressful verbal/auditory stimuli.

“Most all [of these studies] show increases in seizure frequency after high-stress events. Studies have also followed populations who have collectively experienced stressful events, such as the effects of war, trauma or natural disaster, or the death of a loved one,” says Privitera. All of which found increased seizure risk during such a time of stress.

For example, a 2002 study evaluated the occurrence of epileptic seizures during the war in Croatia in the early 1990s. Children from war-affected areas had epileptic seizures more often than children not affected by the war. Additionally, the 10-year follow up showed that patients who had their first epileptic seizure during a time of stress were more likely to have controlled epilepsy or even be off medication years later.

“Stress is a subjective and highly individualized state of mental or emotional strain. Although it’s quite clear that stress is an important and common seizure precipitant, it remains difficult to obtain objective conclusions about a direct causal factor for individual epilepsy patients,” says McKee.

Another aspect of the stress-seizure relationship is the finding by UC researchers that there were higher anxiety levels in patients with epilepsy who report stress as a seizure precipitant. The researchers suggest patients who believe stress is a seizure trigger may want to talk with their health care provider about screening for anxiety.

“Any patient reporting stress as a seizure trigger should be screened for a treatable mood disorder, especially considering that mood disorders are so common within this population,” adds McKee.

The researchers report that while some small prospective trials using general stress reduction methods have shown promise in improving outcomes in people with epilepsy, large-scale, randomized, controlled trials are needed to convince both patients and providers that stress reduction methods should be standard adjunctive treatments for people with epilepsy.

“What I think some of these studies point to is that efforts toward stress reduction techniques, though somewhat inconsistent, have shown promise in reducing seizure frequency. We need future research to establish evidence-based treatments and clarify biological mechanisms of the stress-seizure relationship,” says Privitera.

Overall, he says, recommending stress reduction methods to patients with epilepsy “could improve overall quality of life and reduce seizure frequency at little to no risk.”

Some low risk stress reduction techniques may include controlled deep breathing, relaxation or mindfulness therapy, as well as exercise, or establishing routines.

Source: UC study explores how low risk stress reduction treatments may benefit epilepsy patients

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[WEB SITE] Study investigates plasticity of motor representations in patients with brain tumors

Winner of the Brainlab Community Neurosurgery Award, Sandro Krieg, MD, presented his research, Plasticity of Motor Representations in Patients with Brain Lesions: a Navigated TMS Study, during the 2017 American Association of Neurological Surgeons (AANS) Annual Scientific Meeting.

This study investigated the spatial distributions of motor representations in terms of tumor-induced brain plasticity by analyzing navigated transcranial magnetic stimulation (nTMS) motor maps derived from 100 patients with motor eloquently located brain tumors in or adjacent to the precentral gyrus (PrG).

The research evoked 8,774 motor potentials (MEPs) that were elicited in six muscles of the upper and lower extremity by stimulating four gyri in patients with five possible tumor locations. Regarding the MEP frequency of each muscle-gyrus subdivision per patient, the expected frequency was 3.53 (8,774 divided by 100 patients, further divided by six muscles and four gyri). Accordingly, the patient ratio for each subdivision was calculated by defining the per-patient minimum data points as three.

The tumor-location specific patient ratios were higher for frontal tumors in both gyri than for other tumor locations. This suggests that the finger representation reorganization in these frontal gyri, which corresponds to location of dorsal premotor areas, might be due to within-premotor reorganization rather than relocation of motor function from PrG into premotor areas one might expect from the Rolandic tumors. The research indicates that reorganization of the finger motor representations might be limited along the middle-to-dorsal dimension of the dorsal premotor areas (posterior MFG and SFG) and might not cross rostrally from the primary motor cortex (PrG) to the dorsal premotor cortex.

Source: Study investigates plasticity of motor representations in patients with brain tumors

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[WEB SITE] Cannabidiol shows promise to reduce seizures for people with difficult-to-treat epilepsy

Taking cannabidiol may cut seizures in half for some children and adults with Lennox-Gastaut syndrome (LGS), a severe form of epilepsy, according to new information released today from a large scale controlled clinical study that will be presented at the American Academy of Neurology’s 69th Annual Meeting in Boston, April 22 to 28, 2017. Cannabidiol is a molecule from the cannabis plant that does not have the psychoactive properties that create a “high.”

Nearly 40 percent of people with LGS, which starts in childhood, had at least a 50 percent reduction in drop seizures when taking a liquid form of cannabidiol compared to 15 percent taking a placebo.

When someone has a drop seizure, their muscle tone changes, causing them to collapse. Children and adults with LGS have multiple kinds of seizures, including drop seizures and tonic-clonic seizures, which involve loss of consciousness and full-body convulsions. The seizures are hard to control and usually do not respond well to medications. Intellectual development is usually impaired in people with LGS.

Although the drop seizures of LGS are often very brief, they frequently lead to injury and trips to the hospital emergency room, so any reduction in drop seizure frequency is a benefit.

“Our study found that cannabidiol shows great promise in that it may reduce seizures that are otherwise difficult to control,” said study author Anup Patel, MD, of Nationwide Children’s Hospital and The Ohio State University College of Medicine in Columbus and a member of the American Academy of Neurology.

For the randomized, double-blind, placebo-controlled study, researchers followed 225 people with an average age of 16 for 14 weeks. The participants had an average of 85 drop seizures per month, had already tried an average of six epilepsy drugs that did not work for them and were taking an average of three epilepsy drugs during the study.

Participants were given either a higher dose of 20 mg/kg daily cannabidiol, a lower dose of 10 mg/kg daily cannabidiol or placebo as an add-on to their current medications for 14 weeks.

Those taking the higher dose had a 42 percent reduction in drop seizures overall, and for 40 percent, their seizures were reduced by half or more.

Those taking the lower dose had a 37 percent reduction in drop seizures overall, and for 36 percent, seizures were reduced by half or more.

Those taking the placebo had a 17 percent reduction in drop seizures, and for 15 percent, seizures were reduced by half or more.

There were side effects for 94 percent of those taking the higher dose, 84 percent of those taking the lower dose and 72 percent of those taking placebo, but most side effects were reported as mild to moderate. The two most common were decreased appetite and sleepiness.

Those receiving cannabidiol were up to 2.6 times more likely to say their overall condition had improved than those receiving the placebo, with up to 66 percent reporting improvement compared to 44 percent of those receiving the placebo.

“Our results suggest that cannabidiol may be effective for those with Lennox-Gastaut syndrome in treating drop seizures,” said Patel. “This is important because this kind of epilepsy is incredibly difficult to treat. While there were more side effects for those taking cannabidiol, they were mostly well-tolerated. I believe that it may become an important new treatment option for these patients.”

There is currently a plan to submit a New Drug Application to the FDA later this year.

Source: Cannabidiol shows promise to reduce seizures for people with difficult-to-treat epilepsy

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[WEB SITE] Much of what we know about the brain may be wrong: The problem with fMRI

The past decade has brought us jaw-dropping insights about the hidden workings of our brains, in part thanks to a popular brain scan technique called fMRI. But a major new study has revealed that fMRI interpretation has a serious flaw, one that could mean that much of what we’ve learned about our brains this way might need a second look.

On TV and in movies, we’ve all seen doctors stick an X-ray up on the lightbox and play out a dramatic scene: “What’s that dark spot, doctor?” “Hm…”

In reality, though, a modern medical scan contains so much data, no single pair of doctor’s eyes could possibly interpret it. The brain scan known as fMRI, for functional magnetic resonance imaging, produces a massive data set that can only be understood by custom data analysis software. Armed with this analysis, neuroscientists have used the fMRI scan to produce a series of paradigm-shifting discoveries about our brains.

Now, an unsettling new report, which is causing waves in the neuroscience community, suggests that fMRI’s custom software can be deeply flawed — calling into question many of the most exciting findings in recent neuroscience.

The problem researchers have uncovered is simple: the computer programs designed to sift through the images produced by fMRI scans have a tendency to suggest differences in brain activity where none exist. For instance, humans who are resting, not thinking about anything in particular, not doing anything interesting, can deliver spurious results of differences in brain activity. It’s even been shown to indicate brain activity in a dead salmon, whose stilled brain lit up an MRI as if it were somehow still dreaming of a spawning run.

The report throws into question the results of some portion of the more than 40,000 studies that have been conducted using fMRI, studies that plumb the brainy depths of everything from free will to fear. And scientists are not quite sure how to recover.

“It’s impossible to know how many fMRI studies are wrong, since we do not have access to the original data,” says computer scientist Anders Eklund of Linkoping University in Sweden, who conducted the analysis.

How it should have worked: Start by signing up subjects. Scan their brains while they rest inside an MRI machine. Then scan their brains again when exposed to pictures of spiders, say. Those subjects who are afraid of spiders will have blood rush to those regions of the brain involved in thinking and feeling fear, because such thoughts or feelings are suspected to require more oxygen. With the help of a computer program, the MRI machine then registers differences in hemoglobin, the iron-rich molecule that makes blood red and carries oxygen from place to place. (That’s the functional in fMRI.) The scan then looks at whether those hemoglobin molecules are still carrying oxygen to a given place in the brain, or not, based on how the molecules respond to the powerful magnetic fields. Scan enough brains and see how the fearful differ from the fearless, and perhaps you can identify the brain regions or structures associated with thinking or feeling fear.

That’s the theory, anyway. In order to detect such differences in brain activity, it would be best to scan a large number of brains, but the difficulty and expense often make this impossible. A single MRI scan can cost around $2,600, according to a 2014 NerdWallet analysis. Further, the differences in the blood flow are often tiny. And then there’s the fact that computer programs have to sift the through images of the 1,200 or so cubic centimeters of gelatinous tissue that make up each individual brain and compare them to others, a big data analysis challenge.

Eklund’s report shows that the assumptions behind the main computer programs used to sift such big fMRI data have flaws, as turned up by nearly 3 million random evaluations of the resting brain scans of 499 volunteers from Cambridge, Massachusetts; Beijing; and Oulu, Finland. One program turned out to have a 15-year-old coding error (which has now been fixed) that caused it to detect too much brain activity. This highlights the challenge of researchers working with computer code that they are not capable of checking themselves, a challenge not confined just to neuroscience.

An FMRI scan during working memory tasks.

The brain is even more complicated than we thought.Worse, Eklund and his colleagues found that all the programs assume that brains at rest have the same response to the jet-engine roar of the MRI machine itself as well as whatever random thoughts and feelings occur in the brain. Those assumptions appear to be wrong. The brain at rest is “actually a bit more complex,” Eklund says.

More specifically, the white matter of the brain appears to be underrepresented in fMRI analyses while another specific part of the brain — the posterior cingulate, a region in the middle of the brain that connects to many other parts — shows up as a “hot spot” of activity. As a result, the programs are more likely to single it out as showing extra activity even when there is no difference. “The reason for this is still unknown,” Eklund says.

Overall, the programs had a false positive rate — detecting a difference where none actually existed — of as much as 70 percent.

Unknown unknowns: This does not mean all fMRI studies are wrong. Co-author and statistician Thomas Nichols of the University of Warwick calculates that some 3,500 studies may be affected by such false positives, and such false positives can never be eliminated entirely. But a survey of 241 recent fMRI papers found 96 that could have even worse false-positive rates than those found in this analysis.

“The paper makes an important criticism,” says Nancy Kanwisher, a neuroscientist at MIT (TED Talk: A neural portrait of the human mind), though she points out that it does not undermine those fMRI studies that do not rely on these computer programs.

Nonetheless, it is worrying. “I think the fallout has yet to be fully evaluated. It appears to apply to quite a few studies, certainly the studies done in a generic way that is the bread-and-butter of fMRI,” says Douglas Greve, a neuroimaging specialist at Massachusetts General Hospital. What’s needed is more scrutiny, Greve suggests.

Another argument for open data. Eklund and his colleagues were only able to discover this methodological flaw thanks to the open sharing of group brain scan data by the 1,000 Functional Connectomes Project. Unfortunately, such sharing of brain scan data is more the exception than the norm, which hinders other researchers attempting to re-create the experiment and replicate the results. Such replication is a cornerstone of the scientific method, ensuring that findings are robust. Eklund, for one, therefore encourages neuroimagers to “share their fMRI data, so that other researchers can replicate their findings and re-analyze the data several years later.” Only then can scientists be sure that the undiscovered activity of the human brain is truly revealed … and that dead salmon are not still dreaming.

ABOUT THE AUTHOR

David Biello is an award-winning journalist writing most often about the environment and energy. His book “The Unnatural World” publishes November 2016. It’s about whether the planet has entered a new geologic age as a result of people’s impacts and, if so, what we should do about this Anthropocene. He also hosts documentaries, such as “Beyond the Light Switch” and the forthcoming “The Ethanol Effect” for PBS. He is the science curator for TED.

Source: The problem with fMRI |

 

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[WEB SITE] Your left hand knows what your right hand is doing

The saying goes that “your left hand doesn’t know what your right hand is doing,” but actually, your left hand is paying more attention than you’d think. Researchers at Tel-Aviv University found that when people practiced finger movements with their right hand while watching their left hand on 3D virtual reality headsets, they could use their left hand more efficiently after the exercise. The work, appearing in Cell Reports, provides a new strategy to improve physical therapy for people with limited strength in their hands.

“We are tricking the brain,” says lead author Roy Mukamel, a professor of psychology at Tel Aviv University in Israel. “This entire experiment ended up being a nice demonstration about how to combine software engineering and neuroscience.”

After completing baseline tests to assess the initial motor skills of each hand, 53 participants strapped on virtual reality headsets, which showed simulated versions of their hands. During the first experiment, the participants completed a series of finger movements with their right hand while the screen showed their virtual left hand moving instead. Next, the participants put a motorized glove on their left hand, which moved their fingers to match the motions of the right hand. While this occurred, the headsets again showed their virtual left hand moving instead of their right.

After analyzing the results, the researchers discovered that the left hand’s performance significantly improved (i.e., had more precise movements in a faster amount of time) when the screen showed the left hand. But the most notable improvements occurred when the virtual reality screen showed the left hand moving while the motorized glove moved the right hand in reality.

The researchers also used fMRI to track which brain structures were activated during the experiments in 18 of the participants. The scientists noted that one section of the brain, called the superior parietal lobe, was activated in each person during training. They also discovered that the level of activity in this brain region was correlated to the level of improved performance in the left hand–the more activity, the better the left hand performed.

“Technologically these experiments were a big challenge,” says Mukamel. “We manipulated what people see and combined it with the passive movement of the hand to show that our hands can learn when they’re not moving under voluntary control.”

The researchers are optimistic that this research can be applied to patients in physical therapy programs who have lost the strength or control of their hands. “We need to show a way to obtain high-performance gains relative to other traditional types of therapies,” says Mukamel. “If we can train one hand without voluntarily moving it and still show significant improvements in the motor skills of that hand, then that’s the ideal.”

This work was supported through the Sagol School of Neuroscience and School of Psychological Sciences at Tel-Aviv University in Israel.

Article: Neural Network Underlying Intermanual Skill Transfer in Humans, Ossmy and Mukamel, Cell Reports, 10.1016/j.celrep.2016.11.009, published 13 December 2016.

Source: Your left hand knows what your right hand is doing – Medical News Today

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