neural circuits Archives - Amazing Health Advances

New Technique Connects Lab-Grown “Neural Organoids” to Resemble Brain Circuits

The AHA! Team — Mon, 22 Jul 2024 08:33:29 +0000

Institute of Industrial Science, The University of Tokyo via News-Medical – Chronic kidney disease (CKD) is extremely prevalent among adults, affecting over 800 million individuals worldwide. The idea of growing a functioning human brain-like tissues in a dish has always sounded pretty far-fetched, even to researchers in the field. Towards the future goal, a Japanese and French research team has developed a technique for connecting lab-grown brain-mimicking tissue in a way that resembles circuits in our brain. It is challenging to study exact mechanisms of the brain development and functions. Animal studies are limited by differences between species in brain structure and function, and brain cells grown in the lab tend to lack the characteristic connections of cells in the human brain. What’s more, researchers are increasingly realizing that these interregional connections, and the circuits that they create, are important for many of the brain functions that define us as humans. Previous studies have tried to create brain circuits under laboratory conditions, which have been advancing the field. Researchers from The University of Tokyo have recently found a way to create more physiological connections between lab-grown “neural organoids,” an experimental model tissue in which human stem cells are grown into three-dimensional developmental brain-mimicking structures. The team did this by linking the organoids via axonal bundles, which is similar to how regions are connected in the living human brain. “In single-neural organoids grown under laboratory conditions, the cells start to display relatively simple electrical activity, when we connected two neural organoids with axonal bundles, we were able to see how these bidirectional connections contributed to generating and synchronizing activity patterns between the organoids, showing some similarity to connections between two regions within the brain.” – Tomoya Duenki, co-lead author of the study The cerebral organoids that were connected with axonal bundles showed more complex activity than single organoids or those connected using previous techniques. In addition, when the research team stimulated the axonal bundles using a technique known as optogenetics, the organoid activity was altered accordingly and the organoids were affected by these changes for some time, in a process known as plasticity. “These findings suggest that axonal bundle connections are important for developing complex networks,” explains Yoshiho Ikeuchi, senior author of the study. “Notably, complex brain networks are responsible for many profound functions, such as language, attention, and emotion.” Given that alterations in brain networks have been associated with various neurological and psychiatric conditions, a better understanding of brain networks is important. The ability to study lab-grown human neural circuits will improve our knowledge of how these networks form and change over time in different situations, and may lead to improved treatments for these conditions. Source: Institute of Industrial Science, The University of Tokyo Journal reference: Osaki, T., et al. (2024). Complex activity and short-term plasticity of human cerebral organoids reciprocally connected with axons. Nature Communications. doi.org/10.1038/s41467-024-46787-7. To read the original article click here.

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Blind Man’s Brain Learns to ‘See’ Through His Ears

AHA Publisher — Mon, 19 Jul 2021 07:00:13 +0000

Abigail Klein Leichman via Israel21c – Israeli neuroscientists trained a 50-year-old man, blind from birth, to recognize objects using a sensory substitution algorithm called EyeMusic. Developed by Prof. Amir Amedi, founding director of the Baruch Ivcher Institute for Brain, Cognition & Technology at IDC Herzliya, EyeMusic converts visual stimuli into “soundscapes” — sound units that convey information about geometric shapes. Functional magnetic resonance imaging of the man’s brain before and after he learned to recognize soundscapes revealed that neural circuits in his brain had formed “topographic maps” previously thought incapable of forming after infancy. “The human brain is indeed more plastic during infancy, but it maintains an enormous potential for reprogramming throughout a person’s life,” said Amedi, who did groundbreaking research into sensory substitution devicesat the Hebrew University of Jerusalem before joining IDC in 2019. The latest study, reported in the journal NeuroImage, provides new evidence of the brain’s ability to change. It holds out promise that people can be trained to restore lost function, for example after a stroke. Study co-author Shir Hofstetter from the Spinoza Centre for Neuroimaging in Amsterdam, said that after the subject learned to interpret soundscapes, “his neural circuits were shown to be activated not only in the auditory cortices, but also in the occipital cortex, which receives visual stimuli in sighted people and is not expected to be activated in a congenitally blind individual.” The scans revealed topographic maps tuned to pitch and time that had not existed before. For instance, tones of a similar pitch were represented by adjacent neurons, whereas those of radically different pitches were represented by neurons that were distant from one another. This is the first time that topographic maps have been shown to emerge in an adult human brain. “Critical periods are not permanent cut-off points for developing new sensory abilities — rather, in a way, we can give the brain a second chance at any point in life,” Amedi said. To read the original article click here. For more articles from Israel21c click here.

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From Scaffolding to Screen Time: Understanding a Child’s Developing Brain for Reading

AHA Publisher — Tue, 05 May 2020 07:00:19 +0000

Cognitive Neuroscience Society via EurekAlert – In the debate about nature versus nurture for developing reading skills, cognitive neuroscientists have a clear message: both matter. From infancy, children have a neural scaffolding in place upon which environmental factors refine and build reading skills. In new work being presented today at the Cognitive Neuroscience Society (CNS) virtual meeting, scientists are reporting on these biological and environmental factors — including early screen time — as they uncover biomarkers that can identify children at risk for dyslexia and other reading acquisition disorders. Recycling Neural Circuits “Reading is a relatively new human invention. To read, our brains have to ‘recycle’ neural circuits originally used for other abilities such as visual and language processing, as well as attention and cognitive abilities,” says Tzipi Horowitz-Kraus of The Technion in Israel and Cincinnati Children’s Hospital, who is chairing the CNS symposium about the new work. “The fact that 5-10% of children worldwide, across cultures and genetic backgrounds, suffer from dyslexia suggests that this disability is not limited to a specific language.” Indeed, the research being presented by Horowitz-Kraus and others suggests a variety of biological precursors are present in children prior to school age across languages, and several environmental factors can help or hinder reading acquisition. The goal is to identify children at risk early, to provide the best possible interventions that will improve literacy. The Reading Brain in Infancy One of the biggest insights to come in recent years in the study of reading acquisition is that most interventions to identify and treat dyslexia in school were coming too late. Over the past decade, longitudinal studies of young children coming out of the lab of Nadine Gaab at Harvard Medical School and others at labs globally have shown that the brains of children who will develop dyslexia are already atypical even before they start into kindergarten. “We knew that the brain of someone with dyslexia was different from a control, but we didn’t know if it was something that developed before the onset of formal reading instruction or if it developed in response to a daily failure to learn to read over a significant period of time,” she says. “Our work was the first time MRI imaging could show that some of the brain characteristics predate the onset of reading development,” Gaab says. Underlying Infrastructure And in new work being presented at the CNS meeting and available via preprint, Gaab’s team has shown that, as a group, babies as young as 3 months old have an underlying infrastructure that helps predict success in reading years later. As part of the BOLD (Boston Longitudinal Dyslexia) study, Gaab’s team has scanned the brains of 140 infants who have a familial risk for dyslexia and then followed them over time to study changes in the structure and function of their brains. For the newest data, 45 of the once-infant subjects have now turned 5 or 6 years old, allowing the researchers to map their brain scans from infancy to their pre-reading skills. “What our infant data suggest is that there is a structural brain scaffold in infancy that serves as a foundation,”Gaaab explains. “Language and reading may be a process that refines this pre-existing brain scaffold.” Studying the brains of young children in an MRI machine is far from simple, Gaab explains. When they are babies, the goal is to have the participants sleep in the scanner. So her lab looks like an elaborate daycare center — with adaptable rocking chairs, swings, cribs, and other gear optimized for use with the scanner. While safely sleeping in the MRI, the babies hear stories read to them, allowing the researchers to capture both structural information about their brains but also, surprisingly, functional data. “We were very surprised to see robust language networks activated while the infants sleep,” Gaab says. Testing Pre-Reading Skills As 5- and 6-year-olds returning to the lab, the children identify word sounds in games designed to test their pre-reading skills. As they get older, the children will do increasingly more advanced tasks, such as reading in the scanner. This longitudinal work gives the researchers a big-picture view of reading development rather than just a snapshot view. Gaab’s lab is next working to understand the co-occurrence of disorders such as ADHD and dyscalculia (a math learning disorder) with dyslexia. They also want to understand techniques children successfully use to compensate for dyslexia in the brain. “We now see children are not a clean slate for reading experience,” Gaab says, and they want to not only better understand the determining factors but also inform policy-makers and the public. The Reading Brain On Screen While studying neurobiochemistry for her master’s program, Horowitz-Kraus worked on SAT preparation with her younger brother who was struggling with reading despite his high intelligence in nonverbal tasks. “Observing my brother’s frustration in executing a task that is very intuitive for individuals without dyslexia made me set the goal to seek neurobiological correlates for reading difficulties and to find ways to improve reading ability,” she says. “This way, I thought, the difficulty can be diagnosed objectively, maybe even before reading is formally acquired, and can prove without a doubt that the difficulty is real.” Fifteen years later, Horowitz-Kraus has done just that and, in new research, is seeking to understand how day-to-day conditions affect the neurobiological foundation for reading in the brain. “Although dyslexia is a genetic disorder, the environment has an impact wherein it can reduce or increase reading challenges,” she says. “The brain is extremely plastic at the pre-reading age, and hence negative stimuli, such as exposure to screens, may have an amplifying effect on a child’s outcomes.” Home Literacy Environment In a series of studies, Horowitz-Kraus and colleagues examined how the home literacy environment, including screen exposure, affects the brain circuits of children 3- to 5-years old, in particular executive functions, language and visual processing. As published recently in JAMA Pediatrics, screen-based media use beyond American Academy of Pediatrics guidelines was associated with “lower microstructural integrity of brain white matter tracts supporting language and emergent literacy skills in prekindergarten children.” Earlier work using EEG had found reduced narrative comprehension in preschool children using screens compared to in-person reading. They also have found that screen exposure engages different brain networks in children with dyslexia compared to typical readers. The results suggest, Horowitz-Kraus says, that listening to stories through screens is not similar to joint reading when seeking to nurture the developing brain. “There is no replacement for joint storytelling in engaging neuronal circuits related to future reading,” she says. What Infrastructure Is Needed? Such studies enabled by modern neuroimaging data are allowing researchers for the first time to determine what infrastructure is needed to be able to read and to track the typical and atypical development of this infrastructure — and to develop appropriate early interventions. Both Horowitz-Karus and Gaab envision moving to a more preventative model for reading disorders. “This preventive model is something we embrace a lot in medicine but for some reason, we have not yet done so in education,” Gaab says. She cites cholesterol screening to help identify those at risk for heart disease as a model that could work for dyslexia and other learning disorders. Already their research and others’ have led to new educational policies, including early dyslexia screening in 29 states to identify children at risk in kindergarten. “We and other cognitive neuroscientists hope to continue to contribute to that shift in this model,” Gaab says. To read the original article click here.

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