Tag: hearing

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Dancing Brainwaves – How Sound Reshapes Brain Networks in Real Time

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Photo by jonas mohamadi

Every beep,  tone and new sound you hear travels from the ear to registering in your brain. But what actually happens in your brain when you listen to a continuous stream of sounds? A new study from Aarhus University and University of Oxford published in Advanced Science reveals that the brain doesn’t simply register sound: it dynamically reshapes its organisation in real time, orchestrating a complex interplay of brainwaves in multiple networks.

The research, led by Dr Mattia Rosso and Associate Professor Leonardo Bonetti at the Center for Music in the Brain, Aarhus University, in collaboration with the University of Oxford, introduces a novel neuroimaging method called  FREQ-NESS – Frequency-resolved Network Estimation via Source Separation. Using advanced algorithms, this method disentangles overlapping brain networks based on their dominant frequency. Once a network is identified by its unique frequency, the method can then trace how it propagates in space across the brain.

“We’re used to thinking of brainwaves like fixed stations – alpha, beta, gamma – and of brain anatomy as a set of distinct regions”, says Dr Rosso. “But what we see with FREQ-NESS is much richer. It is long known that brain activity is organised through activity in different frequencies, tuned both internally and to the environment. Starting from this fundamental principle, we’ve designed a method that finds how each frequency is expressed across the brain.”

Opens the door to precise brain mapping

The development of FREQ-NESS represents a major advance in how scientists can investigate the brain’s large-scale dynamics. Unlike traditional methods that rely on predefined frequency bands or regions of interest, the data-driven approach maps the whole brain’s internal organisation with high  spectral and spatial precision. And that opens new possibilities for basic neuroscience, brain-computer interfaces, and clinical diagnostics.

This study adds to a growing body of research exploring how the brain’s rhythmic structure shapes everything from music cognition to general perception and attention, and altered states of consciousness.

“The brain doesn’t just react: it reconfigures. And now we can see it”, says Professor Leonardo Bonetti, co-author and neuroscientist at Center for Music in the Brain, Aarhus University, and at the Centre for Eudaimonia and Human Flourishing, University of Oxford. “This could change how we study brain responses to music and beyond, including consciousness, mind-wandering, and broader interactions with the external world.”

A large-scale research program is now underway to build on this methodology, supported by an international network of neuroscientists. Due to the high reliability across experimental conditions and across datasets – FREQ-NESS might also pave the way for individualised brain mapping, explains Professor Leonardo Bonetti.

Source: Aarhus University

Categories : Genetics NeurologyTags :

Researchers Close in on Genetic Cure for Congenital Deafness

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Researchers are a step closer in the quest to use gene therapy to enable people born deaf to hear, having uncovered a new role for a key protein.

The study, published in Molecular Biology of the Cell, focused on a large gene responsible for an inner-ear protein called otoferlin. Otoferlin mutations are linked to severe congenital hearing loss, a common type of deafness in which patients can hear almost nothing.

“For a long time otoferlin seemed to be a one-trick pony of a protein,” explained Colin Johnson, associate professor of biochemistry and biophysics in the Oregon State UniversityCollege of Science. “A lot of genes will find various things to do, but the otoferlin gene had appeared only to have one purpose and that was to encode sound in the sensory hair cells in the inner ear. Small mutations in otoferlin render people profoundly deaf.”

Because the otoferlin gene is too big as it normally is to package into a delivery vehicle for molecular therapy, Prof Johnson’s team explored the use of a shortened version.

Research led by graduate student Aayushi Manchanda showed the shortened version needed to have part of the gene known as the transmembrane domain, for a surprising reason: without it, the sensory cells matured slowly.

“That was surprising since otoferlin was known to help encode hearing information but had not been thought to be involved in sensory cell development,” Johnson said.

For years, scientists in Prof Johnson’s lab have been working with the otoferlin molecule and in 2017 they identified a shortened form of the gene that can function in the encoding of sound.

To find out if the transmembrane domain of otoferlin needed to be part of the shortened version of the gene, Manchanda shortened the transmembrane domain in zebrafish.

Zebrafish are a small freshwater species that is very popular as a research organism. They grow rapidly, from a cell to a swimming fish in about five days, and share a remarkable similarity to humans at the molecular, genetic and cellular levels due to the conservation of mammalian genes early in their evolution. Embryonic zebrafish are transparent and easily maintained, and are amenable to genetic manipulation.

“The transmembrane domain tethers otoferlin to the cell membrane and intracellular vesicles but it was not clear if this was essential and had to be included in a shortened form of otoferlin,” Manchanda said. “We found that the loss of the transmembrane domain results in the sensory hair cells producing less otoferlin as well as deficits in hair cell activity. The mutation also caused a delay in the maturation of the sensory cells, which was a surprise. Overall the results argue that the transmembrane domain must be included in any gene therapy construct.”

At the molecular level, Manchanda found that a lack of transmembrane domain led to otoferlin not properly linking the neurotransmitter-filled synaptic vesicles to the cell membrane, resulting in less neurotransmitter being released.

“Our study suggests otoferlin’s ability to tether the vesicles to the cell membrane is a key mechanistic step for neurotransmitter release during the encoding of sound,” Manchanda said.

Source: EurekaAlert!