Posts tagged science
Posts tagged science
Conscious Brain-to-Brain Communication in Humans Using Non-Invasive Technologies
Human sensory and motor systems provide the natural means for the exchange of information between individuals, and, hence, the basis for human civilization. The recent development of brain-computer interfaces (BCI) has provided an important element for the creation of brain-to-brain communication systems, and precise brain stimulation techniques are now available for the realization of non-invasive computer-brain interfaces (CBI). These technologies, BCI and CBI, can be combined to realize the vision of non-invasive, computer-mediated brain-to-brain (B2B) communication between subjects (hyperinteraction). Here we demonstrate the conscious transmission of information between human brains through the intact scalp and without intervention of motor or peripheral sensory systems. Pseudo-random binary streams encoding words were transmitted between the minds of emitter and receiver subjects separated by great distances, representing the realization of the first human brain-to-brain interface. In a series of experiments, we established internet-mediated B2B communication by combining a BCI based on voluntary motor imagery-controlled electroencephalographic (EEG) changes with a CBI inducing the conscious perception of phosphenes (light flashes) through neuronavigated, robotized transcranial magnetic stimulation (TMS), with special care taken to block sensory (tactile, visual or auditory) cues. Our results provide a critical proof-of-principle demonstration for the development of conscious B2B communication technologies. More fully developed, related implementations will open new research venues in cognitive, social and clinical neuroscience and the scientific study of consciousness. We envision that hyperinteraction technologies will eventually have a profound impact on the social structure of our civilization and raise important ethical issues.
It may be possible to train the brain to prefer healthy low-calorie foods over unhealthy higher-calorie foods, according to new research by scientists at the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University and at Massachusetts General Hospital. Published online today in the journal Nutrition & Diabetes, a brain scan study in adult men and women suggests that it is possible to reverse the addictive power of unhealthy food while also increasing preference for healthy foods.
“We don’t start out in life loving French fries and hating, for example, whole wheat pasta,” said senior and co-corresponding author Susan B. Roberts, Ph.D., director of the Energy Metabolism Laboratory at the USDA HNRCA, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts University and an adjunct professor of psychiatry at Tufts University School of Medicine. “This conditioning happens over time in response to eating – repeatedly! - what is out there in the toxic food environment.”
Scientists have suspected that, once unhealthy food addiction circuits are established, they may be hard or impossible to reverse, subjecting people who have gained weight to a lifetime of unhealthy food cravings and temptation. To find out whether the brain can be re-trained to support healthy food choices, Roberts and colleagues studied the reward system in thirteen overweight and obese men and women, eight of whom were participants in a new weight loss program designed by Tufts University researchers and five who were in a control group and were not enrolled in the program.
Both groups underwent magnetic resonance imaging (MRI) brain scans at the beginning and end of a six-month period. Among those who participated in the weight loss program, the brain scans revealed changes in areas of the brain reward center associated with learning and addiction. After six months, this area had increased sensitivity to healthy, lower-calorie foods, indicating an increased reward and enjoyment of healthier food cues. The area also showed decreased sensitivity to the unhealthy higher-calorie foods.
“The weight loss program is specifically designed to change how people react to different foods, and our study shows those who participated in it had an increased desire for healthier foods along with a decreased preference for unhealthy foods, the combined effects of which are probably critical for sustainable weight control,” said co-author Sai Krupa Das, Ph.D., a scientist in the Energy Metabolism Laboratory at the USDA HNRCA and an assistant professor at the Friedman School. “To the best of our knowledge this is the first demonstration of this important switch.” The authors hypothesize that several features of the weight loss program were important, including behavior change education and high-fiber, low glycemic menu plans.
“Although other studies have shown that surgical procedures like gastric bypass surgery can decrease how much people enjoy food generally, this is not very satisfactory because it takes away food enjoyment generally rather than making healthier foods more appealing,” said first author and co-corresponding author Thilo Deckersbach, Ph.D., a psychologist at Massachusetts General Hospital. “We show here that it is possible to shift preferences from unhealthy food to healthy food without surgery, and that MRI is an important technique for exploring the brain’s role in food cues.”
“There is much more research to be done here, involving many more participants, long-term follow-up and investigating more areas of the brain,” Roberts added. “But we are very encouraged that, the weight loss program appears to change what foods are tempting to people.”
Bats do not use sight to navigate when flying. Instead, they emit ultrasound pulses and measure the echoes reflected from their surroundings. They have an extremely flexible internal navigation system that enables them to do this. A new study published in Nature Communications shows that when a bat flies close to an object, the number of active neurons in the part of a bat’s brain responsible for processing acoustic information about spatial positioning increases. This information helps these masters of flight to react rapidly and avoid obstacles.
As nocturnal animals, bats are perfectly adapted to a life without light. They emit echolocation sounds and use the delay between the reflected echoes to measure distance to obstacles or prey. In their brains, they have a spatial map representing different echo delays. A study carried out by researchers at Technische Universität München (TUM) has shown for the first time that this map dynamically adapts to external factors.
Closer objects appear larger
When a bat flies in too close to an object, the number of activated neurons in its brain increases. As a result, the object appears disproportionately larger on the bat’s brain map than objects at a safe distance, as if it were magnified. “The map is similar to the navigation systems used in cars in that it shows bats the terrain in which they are moving,” explains study director Dr. Uwe Firzlaff at the TUM Chair of Zoology. “The major difference, however, is that the bats’ inbuilt system warns them of an impending collision by enhancing neuronal signals for objects that are in close proximity.”
Bats constantly adapt their flight maneuvers to their surroundings to avoid collisions with buildings, trees or other animals. The ability to determine lateral distance to other objects also plays a key role here. Which is why bats process more spatial information than just echo delays. “Bats evaluate their own motion and map it against the lateral distance to objects,” elaborates the researcher.
Brain processes complex spatial information
In addition to the echo reflection time, bats process the reflection angle of echoes. They also compare the sound volume of their calls with those of the reflected sound waves and measure the wave spectrum of the echo. “Our research has led us to conclude that bats display much more spatial information on their acoustic maps than just echo reflection.”
The results show that the nerve cells interpret the bats’ rapid responses to external stimuli by enlarging the active area in the brain to display important information. “We may have just uncovered one of the fundamental mechanisms that enables vertebrates to adapt flexibly to continuously changing environments,” concludes Firzlaff.
A fundamental characteristic of neurons that extend into the skin and record touch, so-called first-order neurons in the tactile system, is that they branch in the skin so that each neuron reports touch from many highly-sensitive zones on the skin.
According to researchers at the Department of Integrative Medical Biology, IMB, Umeå University, this branching allows first-order tactile neurons not only to send signals to the brain that something has touched the skin, but also process geometric data about the object touching the skin.
Our work has shown that two types of first-order tactile neurons that supply the sensitive skin at our fingertips not only signal information about when and how intensely an object is touched, but also information about the touched object’s shape, says Andrew Pruszynski, who is one of the researchers behind the study.
The study also shows that the sensitivity of individual neurons to the shape of an object depends on the layout of the neuron’s highly-sensitive zones in the skin.
Perhaps the most surprising result of our study is that these peripheral neurons, which are engaged when a fingertip examines an object, perform the same type of calculations done by neurons in the cerebral cortex. Somewhat simplified, it means that our touch experiences are already processed by neurons in the skin before they reach the brain for further processing, says Andrew Pruszynski.
Swinburne researchers have developed a technique to create a highly sensitive surface for measuring the concentration of a peptide that is a biomarker for early stage Alzheimer’s disease.
(Image caption: Ultrashort-laser pulses were used to write ripples on the surface of sapphire. The self-organised nano-structure of ripples (seen in the image) is a perfect sensing surface after coating with a nanometre-thin layer of gold made by evaporation or sputtering. Such surface ripples were used in the study of amyloid detection.)
Alzheimer’s disease was first recorded more than 100 years ago, but there is still no effective therapy to stop or slow the progression of the disease. Sufferers can lose up to 60 per cent of their neuronal cells before a diagnosis is obtained.
Diagnosis at the very early stages before neuronal degeneration has begun is vital for testing and developing new treatments.
Abnormality of the beta amyloid peptide in cerebrospinal fluid appears to be the earliest and most significant marker of Alzheimer’s. Currently there are no standardised tests to detect these biomarkers.
The researchers have developed a sensor based on nanotechnology that outperforms commercial sensors and demonstrates fast and reliable measurement of beta amyloid oligomers at low concentrations.
The key to the high sensitivity is the laser nano-textured gold coated surface. This sensor can identify concentrations of beta amyloid in a quantitative manner for the first time.
“We showed that sensors based on light scattering can indeed deliver QUANTATIVE measurements and they can be made fast,” Professor of Nanophotonics Saulius Juodkazis said.
“The sensor platform we developed by laser nano-texturing of surfaces is delivering results of the highest sensitivity and repeatability.
“The challenge is to create fast and efficient fabrication of sensors based on nanotechnology and develop new analytical methods of detection. This means we should be able to detect markers of diseases at far lower levels.”
Surface enhanced Raman spectroscopy (SERS) is one of the most sensitive and highly specific label-free detection methods which may evolve as a detection technique for different forms of beta amyloid or as a rapid, low cost technique to validate new biomarkers before developing standard assays for enzyme-linked immunosorbent assays (ELISAs).
This research is a PhD project work of Dr Ricardas Buividas who received his doctorate in May 2014. It was published in the Journal of Biophotonics.
Chinese Doctors Use 3D-Printing in Pioneering Surgery to Replace Half of Man’s Skull
Surgeons at Xijing Hospital in Xi’an, Shaanxi province in Northwest China are using 3D-printing in a pioneering surgery to help rebuild the skull of a man who suffered brain damage in a construction accident.
Hu, a 46-year-old farmer, was overseeing construction to expand his home in Zhouzhi county last October when he was hit by a pile of wood and fell down three storeys.
Although he survived the fall, the left side of his skull was severely crushed and the shattered bone fragments needed to be removed, which has led to a depression of one side of his head.
Due to his injuries, Hu cannot see well out of his left eye, experiences double vision (diplopia) and is also unable to speak and write.
While reading, children and adults alike must avoid confusing mirror-image letters (like b/d or p/q). Why is it difficult to differentiate these letters? When learning to read, our brain must be able to inhibit the mirror-generalization process, a mechanism that facilitates the recognition of identical objects regardless of their orientation, but also prevents the brain from differentiating letters that are different but symmetrical. A study conducted by the researchers of the Laboratoire de Psychologie du Développement et de l’Education de l’Enfant (CNRS / Université Paris Descartes / Université de Caen Basse-Normandie) is available on the website of the Psychonomic Bulletin & Review (Online First Articles).
In recent years, many studies on the process of learning to read have been based on the neuronal recycling hypothesis: the reuse of old brain mechanisms in a new adaptive role —a kind of “biological trick.” Specifically, neurons that are originally dedicated to the rapid identification of objects in the environment, through the mirror-generalization process, are “repurposed” during childhood to specialize in the visual recognition of letters and words.
In this study, the researchers showed 80 young adults pairs of images, first two letters and then two animals, asking them to determine whether they were identical. The readers consistently spent more time determining that two animal images, when preceded by mirror-image letters, were indeed identical. This increase in response time is called “negative priming”: the readers had to inhibit the mirror-generalization process in order to distinguish letters like b/d or p/q. They then needed a little more time to reactivate this strategy when it became useful again to quickly identify animals.
These results show that even adults need to inhibit the mirror-generalization process to avoid reading errors. Children must therefore learn to inhibit this strategy when learning to read. A failure of cognitive inhibition during the recycling of visual neurons in the brain could thus be a factor in dyslexia— a direction worth exploring, in light of these findings.
When we learn, we associate a sensory experience either with other stimuli or with a certain type of behaviour. The neurons in the cerebral cortex that transmit the information modify the synaptic connections that they have with the other neurons. According to a generally-accepted model of synaptic plasticity, a neuron that communicates with others of the same kind emits an electrical impulse as well as activating its synapses transiently. This electrical pulse, combined with the signal received from other neurons, acts to stimulate the synapses. How is it that some neurons are caught up in the communication interplay even when they are barely connected? This is the crucial chicken-or-egg puzzle of synaptic plasticity that a team led by Anthony Holtmaat, professor in the Department of Basic Neurosciences in the Faculty of Medicine at UNIGE, is aiming to solve. The results of their research into memory in silent neurons can be found in the latest edition of Nature.
Learning and memory are governed by a mechanism of sustainable synaptic strengthening. When we embark on a learning experience, our brain associates a sensory experience either with other stimuli or with a certain form of behaviour. The neurons in the cerebral cortex responsible for ensuring the transmission of the relevant information, then modify the synaptic connections that they have with other neurons. This is the very arrangement that subsequently enables the brain to optimise the way information is processed when it is met again, as well as predicting its consequences.
Neuroscientists typically induce electrical pulses in the neurons artificially in order to perform research on synaptic mechanisms.
The neuroscientists from UNIGE, however, chose a different approach in their attempt to discover what happens naturally in the neurons when they receive sensory stimuli. They observed the cerebral cortices of mice whose whiskers were repeatedly stimulated mechanically without an artificially-induced electrical pulse. The rodents use their whiskers as a sensor for navigating and interacting; they are, therefore, a key element for perception in mice.
An extremely low signal is enough
By observing these natural stimuli, professor Holtmaat’s team was able to demonstrate that sensory stimulus alone can generate long-term synaptic strengthening without the neuron discharging either an induced or natural electrical pulse. As a result – and contrary to what was previously believed – the synapses will be strengthened even when the neurons involved in a stimulus remain silent.In addition, if the sensory stimulation lasts over time, the synapses become so strong that the neuron in turn is activated and becomes fully engaged in the neural network. Once activated, the neuron can then further strengthen the synapses in a forwards and backwards movement. These findings could solve the brain’s “What came first?” mystery, as they make it possible to examine all the synaptic pathways that contribute to memory, rather than focusing on whether it is the synapsis or the neuron that activates the other.
The entire brain is mobilised
A second discovery lay in store for the researchers. During the same experiment, they were also able to establish that the stimuli that were most effective in strengthening the synapses came from secondary, non-cortical brain regions rather than major cortical pathways (which convey actual sensory information). Accordingly, storing information would simply require the co-activation of several synaptic pathways in the neuron, even if the latter remains silent. These findings may also have important implications both for the way we understand learning mechanisms and for therapeutic possibilities, in particular for rehabilitation following a stroke or in neurodegenerative disorders. As professor Holtmaat explains: “It is possible that sensory stimulation, when combined with another activity (motor activity, for example), works better for strengthening synaptic connections”. The professor concludes: “In the context of therapy, you could combine two different stimuli as a way of enhancing the effectiveness.”
Until the last few decades, the frontal lobes of the brain were shrouded in mystery and erroneously thought of as nonessential for normal function—hence the frequent use of lobotomies in the early 20th century to treat psychiatric disorders. Now a review publishing August 28 in the Cell Press journal Neuron highlights groundbreaking studies of patients with brain damage that reveal how distinct areas of the frontal lobes are critical for a person’s ability to learn, multitask, control their emotions, socialize, and make real-life decisions. The findings have helped experts rehabilitate patients experiencing damage to this region of the brain.
Although fairly common, damage to the prefrontal lobes (also called the prefrontal cortex) is often overlooked and undiagnosed because patients do not manifest obvious deficits. For example, patients with prefrontal brain damage do not lose any of their senses and often have preserved motor and language abilities, but they may manifest social abnormalities or difficulties with high-level planning in everyday life situations.
"In this review, we aimed to highlight a blend of new studies using cutting edge research techniques to investigate brain damage, but also to relate these new studies to original studies, some of which were published more than a century ago," said lead author Dr. Sara Szczepanski, of the University of California, Berkeley. "There is currently a large push to better understand the functions of the prefrontal cortex, and we believe that our review will make an important contribution to this understanding."
In addition to revealing the functions of different areas within the prefrontal cortex, studies have also demonstrated the flexibility of the region, which has helped experts optimize cognitive therapy techniques to enable patients with brain damage to learn new skills and compensate for their impairments.
The review indicates that by studying patients with damage to the prefrontal cortex, investigators can gain insights into this still-mysterious region of the brain that is critical for complex human skills and behavior.
The effects of very early Alzheimer’s disease on the characteristics of writing by a renowned author
Iris Murdoch (I.M.) was among the most celebrated British writers of the post-war era. Her final novel, however, received a less than enthusiastic critical response on its publication in 1995. Not long afterwards, I.M. began to show signs of insidious cognitive decline, and received a diagnosis of Alzheimer’s disease, which was confirmed histologically after her death in 1999. Anecdotal evidence, as well as the natural history of the condition, would suggest that the changes of Alzheimer’s disease were already established in I.M. while she was writing her final work. The end product was unlikely, however, to have been influenced by the compensatory use of dictionaries or thesauri, let alone by later editorial interference. These facts present a unique opportunity to examine the effects of the early stages of Alzheimer’s disease on spontaneous written output from an individual with exceptional expertise in this area. Techniques of automated textual analysis were used to obtain detailed comparisons among three of her novels: her first published work, a work written during the prime of her creative life and the final novel. Whilst there were few disparities at the levels of overall structure and syntax, measures of lexical diversity and the lexical characteristics of these three texts varied markedly and in a consistent fashion. This unique set of findings is discussed in the context of the debate as to whether syntax and semantics decline separately or in parallel in patients with Alzheimer’s disease.