Tag: brain imaging

Categories : Lab Tests and Imaging NeurologyTags :

“Movies” with Colour and Music Visualise Brain Activity Data in Beautiful Detail

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Novel toolkit translates neuroimaging data into audiovisual formats to aid interpretation

Simple audiovisualisation of wide field neural activity. Adapted from Thibodeaux et al., 2024, PLOS ONE, CC-BY 4.0

Complex neuroimaging data can be explored through translation into an audiovisual format – a video with accompanying musical soundtrack – to help interpret what happens in the brain when performing certain behaviours. David Thibodeaux and colleagues at Columbia University, US, present this technique in the open-access journal PLOS ONE on February 21, 2024. Examples of these beautiful “brain movies” are included below.

Recent technological advances have made it possible for multiple components of activity in the awake brain to be recorded in real time. Scientists can now observe, for instance, what happens in a mouse’s brain when it performs specific behaviours or receives a certain stimulus. However, such research produces large quantities of data that can be difficult to intuitively explore to gain insights into the biological mechanisms behind brain activity patterns.

Prior research has shown that some brain imaging data can be translated into audible representations. Building on such approaches, Thibodeaux and colleagues developed a flexible toolkit that enables translation of different types of brain imaging data – and accompanying video recordings of lab animal behaviour – into audiovisual representations.

The researchers then demonstrated the new technique in three different experimental settings, showing how audiovisual representations can be prepared with data from various brain imaging approaches, including 2D wide-field optical mapping (WFOM) and 3D swept confocally aligned planar excitation (SCAPE) microscopy.

The toolkit was applied to previously-collected WFOM data that detected both neural activity and brain blood flow changes in mice engaging in different behaviours, such as running or grooming. Neuronal data was represented by piano sounds that struck in time with spikes in brain activity, with the volume of each note indicating magnitude of activity and its pitch indicating the location in the brain where the activity occurred. Meanwhile, blood flow data were represented by violin sounds. The piano and violin sounds, played in real time, demonstrate the coupled relationship between neuronal activity and blood flow. Viewed alongside a video of the mouse, a viewer can discern which patterns of brain activity corresponded to different behaviours.

The authors note that their toolkit is not a substitute for quantitative analysis of neuroimaging data. Nonetheless, it could help scientists screen large datasets for patterns that might otherwise have gone unnoticed and are worth further analysis.

The authors add: “Listening to and seeing representations of [brain activity] data is an immersive experience that can tap into this capacity of ours to recognise and interpret patterns (consider the online security feature that asks you to “select traffic lights in this image” – a challenge beyond most computers, but trivial for our brains)…[It] is almost impossible to watch and focus on both the time-varying [brain activity] data and the behavior video at the same time, our eyes will need to flick back and forth to see things that happen together. You generally need to continually replay clips over and over to be able to figure out what happened at a particular moment. Having an auditory representation of the data makes it much simpler to see (and hear) when things happen at the exact same time.”

  1. Audiovisualisation of neural activity from the dorsal surface of the thinned skull cortex of the awake mouse.
  2. Audiovisualisation of neural activity from the dorsal surface of the thinned skull cortex of the ketamine/xylazine anaesthetised mouse.
  3. Audiovisualisation of SCAPE microscopy data capturing calcium activity in apical dendrites in the awake mouse brain.
  4. Audiovisualisation of neural activity and blood flow from the dorsal surface of the thinned skull cortex of the awake mouse.

Video Credits: Thibodeaux et al., 2024, PLOS ONE, CC-BY 4.0

Categories : NeurologyTags :

Neurons in Developing Brains are Connected by Nanoscopic Tunnels

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Example of 3D imaging of segmented granule cells shown in green and orange, with nuclei in blue and purple respectively, and mitochondria in yellow. A thin connection can be seen between the two cells in blue, with subcompartments attached to the tube containing the mitochondria, shown in pink. Credit: Diego Cordero / Membrane Traffic and Pathogenesis Unit, Institut Pasteur

Over a hundred years after the discovery of the neuron by neuroanatomist Santiago Ramón y Cajal, scientists continue to deepen their knowledge of the brain and its development. Now, scientists detail novel insights into how cells in the outer layers of the brain interact immediately after birth during formation of the cerebellum, the brain region towards the back of the skull. Publishing their results in in Science Advances, the scientists demonstrated a novel type of connection between neural precursor cells via nanotubes, even before synapses form.

In 2009, Chiara Zurzolo’s team from the Institut Pasteur identified a novel mechanism for direct communication between neuronal cells in culture via nanoscopic tunnels, known as tunnelling nanotubes. These are involved in the spread of various toxic proteins that accumulate in the brain during neurodegenerative diseases – but may also be tapped for the treatment of diseases or cancers.

In this new study, the researchers discovered nanoscopic tunnels that connect precursor cells in the brain, more specifically the cerebellum – an area that develops after birth and is important for making postural adjustments to maintain balance – as they mature into neurons. These tunnels, although similar in size, vary in shape from one to another: some contain branches while others don’t, some are enveloped by the cells they connect while others are exposed to their local environment. The authors believe these intercellular connections (ICs) may enable the exchange of molecules that help pre-neuronal cells physically migrate across various layers and reach their final destination as the brain develops.

Intriguingly, ICs share anatomical similarities with bridges formed when cells finish dividing. “ICs could derive from cellular division but persist during cell migration, so this study could shed light on the mechanisms allowing coordination between cell division and migration implicated in brain development. On the other hand, ICs established between cells post mitotically could allow direct exchange between cells beyond the usual synaptic connections, representing a revolution in our understanding of brain connectivity. We show that there are not only synapses allowing communication between cells in the brain, there are also nanotubes,” says Dr Zurzolo, senior author and head of the Membrane Traffic and Pathogenesis Unit (Institut Pasteur/CNRS).

To achieve these discoveries, the researchers used a three-dimensional (3D) electron microscopy method and brain cells from mouse models to study how the brain regions communicate between each other. Very high resolution neural network maps could thus be reconstructed. The 3D cerebellum volume produced and used for the study contains over 2000 cells. “If you really want to understand how cells behave in a three-dimensional environment, and map the location and distribution of these tunnels, you have to reconstruct an entire ecosystem of the brain, which requires extraordinary effort with twenty or so people involved over 4 years,” said the article’s first author Diego Cordero.

To meet the challenges of working with the wide range of cell types the brain contains, the authors used an AI tool to automatically distinguish cortical layers. Furthermore, they developed an open-source program called CellWalker to characterise morphological features of 3D segments. The tissue block was reconstructed from brain section images. This program being made freely available will enable scientists to quickly and easily analyse the complex anatomical information embedded in these types of microscope images.

The next step will be to identify the biological function of these cellular tunnels to understand their role in the development of the central nervous system and in other brain regions, and their function in communication between brain cells in neurodegenerative diseases and cancers.

Source: Institut Pasteur

Categories : Diet and Nutrition Mental HealthTags :

Changes in Brain Structures Found in Patients with Anorexia Nervosa

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Anorexia photo created by freepik – www.freepik.com

A major study published in the journal Biological Psychiatry has revealed key differences in brain structure between people with and without anorexia nervosa.

Anorexia nervosa is an eating disorder defined by restriction of energy intake relative to requirements, leading to a significantly low body weight. Patients will have an intense fear of gaining weight and distorted body image and are unable to recognise the seriousness of their significantly low body weight.

Little is known about why some people develop anorexia whilst others do not, although biological factors are widely recognised. The findings from the study, which was coordinated by neuroscientists at the University of Bath with international partners, draws on extensive analyses of brain scans taken from patients around the world and goes some way to answering the question.

They reveal that people with anorexia demonstrate ‘sizeable reductions’ in three critical measures of the brain: cortical thickness, subcortical volumes and cortical surface area. Brain size reductions are significant due the implied loss of brain cells or the connections between them.

The results are some of the clearest yet to show links between structural changes in the brain and eating disorders. The team says that the effect sizes in their study for anorexia are in fact the largest of any psychiatric disorder investigated to date.

This means that people with anorexia showed reductions in brain size and shape two to four times greater than people with conditions such as depression, ADHD, or OCD. The changes observed in brain size for anorexia may be attributable to reductions in body mass index (BMI).

The team emphasised the importance of early treatment to help people with anorexia avoid long-term, structural brain changes. Existing treatment typically involves forms of cognitive behavioural therapy and, critically, weight gain. Many people with anorexia are successfully treated and these results show the positive impact such treatment has on brain structure.

Their study pooled nearly 2000 pre-existing brain scans for people with anorexia, including people in recovery and ‘healthy controls’ (people neither with anorexia nor in recovery). For people in recovery from anorexia, the study found that reductions in brain structure were less severe, suggesting that, with appropriate early treatment and support, brain self-repair is possible.

Lead researcher, Dr Esther Walton of the Department of Psychology at the University of Bath explained: “For this study, we worked intensively over several years with research teams across the world. Being able to combine thousands of brain scans from people with anorexia allowed us to study the brain changes that might characterise this disorder in much greater detail.

“We found that the large reductions in brain structure, which we observed in patients, were less noticeable in patients already on the path to recovery. This is a good sign, because it indicates that these changes might not be permanent. With the right treatment, the brain might be able to bounce back.”

“The international scale of this work is extraordinary,” said Paul Thompson, a professor of neurology and lead scientist for the ENIGMA Consortium, an international effort to understand the link between brain structure, function and mental health. “Scientists from 22 centres worldwide pooled their brain scans to create the most detailed picture to date of how anorexia affects the brain. The brain changes in anorexia were more severe than in other any psychiatric condition we have studied. Effects of treatments and interventions can now be evaluated, using these new brain maps as a reference.”

He added: “This study is novel in term of the thousands of brain scans analysed, revealing that anorexia affects the brain more profoundly than any other psychiatric condition. This really is a wake-up call, showing the need for early interventions for people with eating disorders.”

Source: University of Bath

Categories : Neurology Substance UseTags :

A Brain ‘Breathalyser’ for THC Intoxication

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Image by Falkurian Design on Unsplash

Scientists have developed a noninvasive brain imaging procedure to identify individuals whose performance has been impaired by THC, the psychoactive ingredient of cannabis. As reported in Neuropsychopharmacology, the technique uses functional near-infrared spectroscopy (fNIRS) to measure brain activation patterns linked to THC intoxication. The technology could have a great impact on road and workplace safety. 

The increasing legalisation of cannabis has driven the need for a portable brain imaging procedure that can distinguish between THC-caused impairment and mild intoxication. “Our research represents a novel direction for impairment testing in the field,” explained lead author Jodi Gilman, PhD. “Our goal was to determine if cannabis impairment could be detected from activity of the brain on an individual level. This is a critical issue because a ‘breathalyser’ type of approach will not work for detecting cannabis impairment, which makes it very difficult to objectively assess impairment from THC during a traffic stop.”

In previous studies, THC has been shown to impair cognitive and psychomotor performance essential to safe driving, a factor thought to at least double the risk of fatal motor vehicle accidents. However, concentration of THC in the body does not correspond well to functional impairment. Regular cannabis users often can have high levels of THC in the body and not be impaired. Metabolites of THC can remain in the bloodstream for weeks after the last cannabis use, well beyond the period of intoxication. Thus, there is a need for a different method to determine impairment from cannabis intoxication.

In the study, 169 cannabis users underwent fNIRS brain imaging before and after receiving either oral THC or a placebo. Participants who reported intoxication after being given oral THC showed an increased oxygenated haemoglobin concentration (HbO) – a type of neural activity signature from the prefrontal cortex region of the brain – compared to those who reported low or no intoxication.

“Identification of acute impairment from THC intoxication through portable brain imaging could be a vital tool in the hands of police officers in the field,” said senior author and principal investigator A. Eden Evins, MD, MPH, founding director of the Center for Addiction Medicine. “The accuracy of this method was confirmed by the fact impairment determined by machine learning models using only information from fNIRS matched self-report and clinical assessment of impairment 76% of the time.”

The study suggested the feasibility of inexpensive, lightweight, battery-powered fNIRS devices that could be incorporated into a headband or cap, and thus require minimal set-up time.

“Companies are developing breathalyser devices that only measure exposure to cannabis but not impairment from cannabis,” said Dr Gilman. “We need a method that won’t penalise medical marijuana users or others with insufficient amounts of cannabis in their system to impair their performance. While it requires further study, we believe brain-based testing could provide an objective, practical and much needed solution.”

Source: Massachusetts General Hospital