NS/ Memory problems can be improved with laser therapy
Neuroscience biweekly vol. 73, 7th December — 21st December
TL;DR
- Laser light therapy has been shown to be effective in improving short-term memory, according to a new study. Scientists demonstrated that the therapy, which is non-invasive, could improve short-term, or working memory, in people by up to 25 percent.
- A new study has unraveled the neural circuits that explain how green light can relieve some cases of chronic pain. The neurons ultimately activate the brain’s own opioid system.
- Researchers have identified a variant of the gene in some patients with amyotrophic lateral sclerosis (ALS). Using human-induced pluripotent stem (iPS) cells, subsequent investigations revealed this variant excessively recruited RNA-binding proteins and disrupted the synaptic formation, which is considered the early impairment in ALS. When excessive binding was blocked, the synaptic formation was recovered. These findings describe one of the mechanisms that cause ALS and offer new insights for treatment.
- An interdisciplinary research team has found important clues about the functioning of the sensorimotor cortex. The new findings on neuronal activities in this brain area could be helpful for the further development and use of so-called neuroprostheses. These have an interface with the nervous system and are intended to help compensate for neuronal dysfunctions.
- When neurons are damaged by degenerative disease or injury, they have little, if any, ability to heal on their own. Restoring neural networks and their normal function is therefore a significant challenge in the field of tissue engineering. Researchers have developed a novel technique to overcome this challenge using nanotechnology and magnetic manipulations, one of the most innovative approaches to creating neural networks.
- Researchers are learning more about how traumatic events may physically change our brains. Neurologists have revealed changes to a brain mechanism used for learning and survival may play a role in how someone responds to a threat following a traumatic experience. Another study found that another mechanism responsible for emotion and memory is impacted and may make it difficult for someone with PTSD to discriminate between safety, danger, or reward. It overgeneralizes danger. These findings could significantly advance future treatments.
- Scientists have examined the records of 87 patients admitted to the hospital with brain abscesses and found that the 52 patients for whom no cause had been found were about three times as likely to have oral bacteria present in their samples.
- A recent study details the neuronal response to excessive iron accumulation, which is associated with age-related neurodegenerative diseases. Iron (Fe) accumulates in the brain cortex with aging. A plethora of studies indicate that progressive iron accumulation in the substantia nigra (SN) in the aged human brain is a major risk factor for Parkinson’s disease (PD) and other neurodegenerative diseases, but not everyone. This is because our body has plans to respond specifically to iron overloading.
- Audio cues can not only help us to recognize objects more quickly but can even alter our visual perception. That is, pair birdsong with a bird and we see a bird — but replace that birdsong with a squirrel’s chatter, and we’re not quite so sure what we’re looking at.
- New research led by scientists at the University of Colorado Boulder suggests that eyes may really be the window to the soul — or, at least, how humans dart their eyes may reveal valuable information about how they make decisions. New findings from mechanical engineers could, one day, help doctors screen patients for illnesses like depression or Parkinson’s Disease.
- And more!
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Latest news and research
Transcranial photobiomodulation enhances visual working memory capacity in humans
Chenguang Zhao, Dongwei Li, Yuanjun Kong, Hongyu Liu, Yiqing Hu, Haijing Niu, Ole Jensen, Xiaoli Li, Hanli Liu, Yan Song. . Science Advances
Laser light therapy has been shown to be effective in improving short term memory in a study published in Science Advances.
Scientists at the University of Birmingham in the UK and Beijing Normal University in China, demonstrated that the therapy, which is non-invasive, could improve short term, or working memory in people by up to 25 per cent.
The treatment, called transcranial photobiomodulation (tPBM), is applied to an area of the brain known as the right prefrontal cortex. This area is widely recognised as important for working memory. In their experiment, the team showed how working memory improved among research participants after several minutes of treatment. They were also able to track the changes in brain activity using electroencephalogram (EEG) monitoring during treatment and testing.
Previous studies have shown that laser light treatment will improve working memory in mice, and human studies have shown tPBM treatment can improve accuracy, speed up reaction time and improve high-order functions such as attention and emotion.
This is the first study, however, to confirm a link between tPBM and working memory in humans.
Dongwei Li, a visiting PhD student in the University of Birmingham’s Centre for Human Brain Health, is co-author on the paper.
He said: “People with conditions like ADHD (attention deficit hyperactivity disorder) or other attention-related conditions could benefit from this type of treatment, which is safe, simple and non-invasive, with no side-effects.”
In the study researchers at Beijing Normal University carried out experiments with 90 male and female participants aged between 18 and 25. Participants were treated with laser light to the right prefrontal cortex at wavelengths of 1064 nm, while others were treated at a shorter wavelength, or treatment was delivered to the left prefrontal cortex. Each participant was also treated with a sham, or inactive, tPBM to rule out the placebo effect.
After tPBM treatment over 12 minutes, the participants were asked to remember the orientations or colour of a set of items displayed on a screen. The participants treated with laser light to the right prefrontal cortex at 1064 nm showed clear improvements in memory over those who had received the other treatments. While participants receiving other treatment variations were about to remember between 3 and 4 of the test objects, those with the targeted treatment were able to recall between 4 and 5 objects.
Data, including from electroencephalogram (EEG) monitoring during the experiment was analysed at the University of Birmingham and showed changes in brain activity that also predicted the improvements in memory performance.
The researchers do not yet know precisely why the treatment results in positive effects on working memory, nor how long the effects will last. Further research is planned to investigate these aspects.
Professor Ole Jensen, also at the Centre for Human Brain Health, said: “We need further research to understand exactly why the tPBM is having this positive effect, but it’s possible that the light is stimulating the astrocytes — the powerplants — in the nerve cells within the prefrontal cortex, and this has a positive effect on the cells’ efficiency. We will also be investigating how long the effects might last. Clearly if these experiments are to lead to a clinical intervention, we will need to see long-lasting benefits.”
Green light analgesia in mice is mediated by visual activation of enkephalinergic neurons in the ventrolateral geniculate nucleus
by Tang Y, Liu A, Lv S et al. . Sci. Trans. Med
A new study has unraveled the neural circuits that explain how green light can relieve some cases of chronic pain. The neurons ultimately activate the brain’s own opioid system.
To many people living with chronic pain, routine pharmacological treatments provide no relief from their discomfort or have devastating side effects. To address these intractable conditions, clinicians have tried approaches that stray far from the standard drug-based model of pain relief. For some, these interventions can provide long-awaited benefits from their pain. One of these approaches is light therapy (phototherapy), where patients are exposed to light of certain wavelengths and intensities to try and relieve pain.
This approach remains experimental but has been deployed, with some success, to reduce pain in conditions like lower back pain, fibromyalgia, migraine and neuropathic pain. Of the wavelengths used, green light has most commonly appeared to have a beneficial effect.
While the focus for patients is undoubtedly on whether these treatments work, for researchers the why of phototherapy has proved intriguing. A new paper has used mouse models of pain to dig into the neural mechanisms behind light-based pain relief, suggesting that activation of the brain’s natural opioid receptors may play a role.
Pain relief is just one application of light in medicine, or phototherapy. Previous studies have investigated phototherapy for the inflammatory skin disease psoriasis, sleep and affective disorders and even, in combination therapies, for nanomedicine in cancer treatment.
The research, published in Science Translational Medicine, was authored by a Chinese research team led by Fudan University’s Prof. Yu-Qiu Zhang.
The effect of light on pain reduction has been well-established in pre-clinical models, so the researchers’ first step was to confirm these earlier findings by showing that green light exposure in mice with a form of arthritis reduced pain. They then explored how this effect was altered in mice that lacked various structures in their eyes that detected visual input.
The mammalian eye receives input through three types of receptors — each of which respond to different wavelengths of light: rods and cones in the outer retina, and a third class of receptor called melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGC) in the inner retina. The researchers showed that when rods and cones were absent, the mice received no benefit from the green light stimulation. When only cones were absent, the effect was also completely abolished, but mice with no rod receptors still had a mild reduction in pain. When ipRGCs were removed, the mice showed no reduction in pain. This suggested to the researchers that the neural pathway they were unraveling began with rod and cone photoreceptors.
Rods and cones feed the information they receive about the outside world onto retinal ganglion cells (RGCs) that convey these signals to higher brain areas. Zhang and team followed this biological thread, using genetic or pharmacological silencing of particular neuronal populations at each stage. They found that connections between the RGCs and the ventral lateral geniculate nucleus (vLGN), a part of the thalamus (the brain’s sensory switchboard) that processes visual information, mediated the analgesic effect.
The vLGN is filled with neurons that send inhibitory signals using the neurotransmitter GABA. The team noted that 32% of the GABAergic neurons in the vLGN also expressed the Penk gene, which codes for a protein, PENK.
This is a precursor to another molecule, ENK, which activates opioid receptors in the brain. The PENK-producing neurons communicated with a region of the brain called the dorsal raphe nucleus (DRN) found in the brainstem. The DRN is thought to have an important role in pain control. When the researchers genetically altered their mice so that their brains couldn’t send PENK to the DRN, the pain-reducing effect of green light disappeared: the team had found the end of their path.
But it isn’t the end for the research field. Experiments utilizing genetic knockout animals to explore the contribution of various brain circuitry to observed behavior are now a staple of neuroscience. The paper’s authors acknowledge that other structures in the cortex might also play a role in the effects of light therapy, and more circuity-untangling studies will be required to separate these different strands.
Another pressing question is why exactly green light would have an analgesic effect in the first place. What could the evolutionary benefit of such a mechanism be? The authors point in their discussion towards a disparate research body that draws from neuroscience and psychology.
“Exposure to an environment rich in the color green (such as [the Japanese and Chinese practice] forest bathing) can decrease physiological and psychological pain. Psychology studies have shown that “green” conveys positive information related to happiness,” the authors write.
The authors also point to research suggesting that other forms of sensory input can mitigate pain: a 2019 paper showed than when humans were exposed to painful stimuli, those who were simultaneously given a sweet smell or taste stimulation rated the pain lower than those given a bitter input.
There are complex interplays involved between our many senses, including pain detection, and the authors finally conclude that the ultimate reason for their findings “might be explained by functional connectivity among primary somatosensory, visual, auditory cortex, and other cortical areas (such as prefrontal cortex) that participate in cross-modal processing.”
TheSYNGAP13’UTR variant in ALS patients causes aberrantSYNGAP1splicing and dendritic spine loss by recruiting HNRNPK
by Satoshi Yokoi, Takuji Ito, Kentaro Sahashi, Masahiro Nakatochi, Ryoichi Nakamura, Genki Tohnai, Yusuke Fujioka, Shinsuke Ishigaki, Tsuyoshi Udagawa, Yuishin Izumi, Mitsuya Morita, Osamu Kano, Masaya Oda, Takefumi Sone, Hideyuki Okano, Naoki Atsuta, Masahisa Katsuno, Yohei Okada, Gen Sobue in The Journal of Neuroscience
Researchers at Nagoya University in Japan have identified a novel genetic variant found in some patients with Amyotrophic lateral sclerosis (ALS). Employing human-induced pluripotent stem (iPS) cells, they detailed the process by which this variant relates to ALS. The investigators expect this mechanism to be a new therapeutic target for ALS treatment. The findings are reported in the Journal of Neuroscience.
ALS is a progressive and fatal neurodegenerative disease where a person gradually loses motor neurons and has muscle weakness. The mechanisms and causes of this disease are not well understood and there is no treatment. Furthermore, ALS is a diverse disease; different patients seem to have different causes, mechanisms, and symptoms. Researchers know that a protein called Fused-in sarcoma (FUS) plays a key role in the disease. Ordinarily, FUS binds to RNA and regulates functions of RNA. On the other hand, FUS dysfunctions are associated with various neurodegenerative diseases, including ALS.
Dr. Satoshi Yokoi and his colleagues in the Department of Neurology, Nagoya University Graduate School of Medicine, have been studying this FUS protein. Previously, they found that the FUS protein interacted with RNA that encodes a protein called SYNGAP1. SYNGAP1 helps with synaptic formation, which is essential for neurons to work together.
“Currently, no study has reported that SYNGAP1 is involved in the mechanism of ALS. However, given its close relationship with FUS, we wanted to investigate whether SYNGAP1 has anything to do with ALS,” said Dr. Yokoi, a lead author of the study.
First, the team searched for a variant of the SYNGAP1 gene in patients with ALS. They found seven out of 807 patients who had the variant. Next, to examine the behavior of the SYNGAP1 variant, they replicated this variant gene in human iPS-derived motor neurons. An iPS cell is a type of stem cell that scientists can transform into any type of cell in the body, including neurons. It is especially useful in medical research because researchers can generate, for example, diseased cells and conduct different tests on them in a living state. This contrasts with traditional methods in which researchers conduct tests on animal cells or outside of a living organism. In this study, the researchers generated motor neurons with the SYNGAP1 variant from iPS cells. In these neurons, researchers observed several abnormal behaviors compared to normal motor neurons. Especially, the variant excessively recruited the FUS protein, as well as to another RNA-binding protein called HNRNPK. This excessive binding inhibited synaptic formation. In particular, excessive recruitment of HNRNPK, rather than FUS, seemed to be a primary cause of synaptic dysfunction with the SYNGAP1 variant. Furthermore, when researchers applied antisense RNA that blocks the excessive binding of HNRNPK to SYNGAP1 RNA, they recovered synaptic formation, meaning that motor neurons can work together. This indicates that, in the future, scientists could utilize antisense RNA to develop ALS drugs.
Excessive binding of HNRNPK to SYNGAP1 was causing synaptic abnormality, which explains the process of early-stage ALS when synapse loss takes place. Additionally, while previous ALS research focused on FUS, this study underscored the crucial roles of SYNGAP1 and HNRNPK. The antisense RNA used in the current research is only effective for those patients with the variant SYNGAP1. Nonetheless, the researchers hope that the discovery of this new mechanism can provide new insight into other types of ALS.
Interestingly, this study also found that SYNGAP1 behaved differently in human iPS cells compared to the mouse model, which had been used for SYNGAP1 research.
“We believe that using human-derived samples is crucial so that the observations from these cells directly apply to patients,” said Dr. Yokoi.
Although the researchers described one mechanism of ALS, much remains to be investigated because ALS involves multiple different mechanisms and causes.
“The ALS patients I see in my daily practice have yet to receive curative treatment. We will continue research to find something that can apply to future ALS treatments,” said Dr. Yokoi.
Conserved structures of neural activity in sensorimotor cortex of freely moving rats allow cross-subject decoding
by Svenja Melbaum, Eleonora Russo, David Eriksson, Artur Schneider, Daniel Durstewitz, Thomas Brox, Ilka Diester in Nature Communications
An interdisciplinary research team at the University of Freiburg has found important clues about the functioning of the sensorimotor cortex. The new findings on neuronal activities in this brain area could be helpful for the further development and use of so-called neuroprostheses. These have an interface with the nervous system and are intended to help compensate for neuronal dysfunctions. “Our results will contribute to the improvement of neuroprosthetic approaches while shortening the training period of patients with prostheses,” says neurobiologist Prof. Dr. Ilka Diester from the Faculty of Biology at the University of Freiburg. The results have just been published in the journal Nature Communications.
The research project also involved the working groups of computer scientist Prof. Dr. Thomas Brox from the University of Freiburg and neuroscientist Prof. Dr. Daniel Durstewitz from the Central Institute of Mental Health in Mannheim. The team found evidence of conserved structures of neuronal activity in the sensorimotor cortex of freely moving rats. The electrophysiological recordings across the entire bilateral sensorimotor cortex allow conclusions about the respective contributions of the premotor, motor and sensory areas. In particular, the researchers found a clear gradient for a contralateral bias, i.e. for movements of the opposite half of the body, from anterior to posterior regions.
Previous findings on sensorimotor cortex are mostly based on highly constrained, stereotyped movements in a laboratory setting. The current work uses recordings on freely moving subjects using 3D tracking and addresses the question of the transferability of knowledge about neural control of movements from constrained behavior to a freely moving condition, a prerequisite for understanding the brain under more natural conditions as well as for the further development of neuroprosthetic devices.
The team used a dimensionality reduction and neural data alignment method. Thus, the high-dimensional neuronal patterns were reduced to a low-dimensional representation by means of their similarity to other patterns, resulting in geometric structures in the visual representation. These geometric patterns were then automatically aligned with each other, similar to the image of holding a magnet to a pack of nails. These then align themselves in a certain direction. Based on such aligned geometric structures, the researchers were able to decipher behavioral categories across recording sessions and even across individuals, and find corresponding evidence of conserved structures of neural activity.
Bioengineering 3D Neural Networks Using Magnetic Manipulations
by Reut Plen, Alejandra Smith, Ofir Blum, Or Aloni, Uri Locker, Zehavit Shapira, Shlomo Margel, Orit Shefi in Advanced Functional Materials
Neurons are the fundamental units of the brain and nervous system, the cells responsible for receiving sensory input from the external world, for sending motor commands to our muscles, and for transforming and relaying the electrical signals at every step in between. Neurons, also called nerve cells, are composed of three main parts: the cell body, the dendrites and the axon — a long, thin extension that is responsible for communicating with other cells.
When neurons are damaged by degenerative disease or injury, they have little, if any, ability to heal on their own. Restoring neural networks and their normal function is therefore a significant challenge in the field of tissue engineering.
Prof. Orit Shefi and doctoral student Reut Plen from the Kofkin Faculty of Engineering at Bar-Ilan University have developed a novel technique to overcome this challenge using nanotechnology and magnetic manipulations, one of the most innovative approaches to creating neural networks.
To create neural networks, the researchers injected magnetic iron oxide nanoparticles into neural progenitor cells, thus turning the cells into independent magnetic units. Next, they exposed the progenitor cells, known to develop into neurons, to a number of pre-adjusted magnetic fields and remotely directed their movement within a three-dimensional and multi-layered collagen substrate that mimics the natural characteristics of body tissue. Through these magnetic manipulations, they created three-dimensional “mini-brains” — functional and multi-layered neural networks that mimic elements found in the brain of mammals.
After the collagen solution solidified into a gel, the cells remained in place according to the remotely applied magnetic fields. Within a few days, the cells developed into mature neurons, formed extensions and connections, demonstrated electrical activity and thrived in the collagen gel for at least 21 days.
“This method paves the way for the creation of 3D cell architecture on a customized scale for use in bioengineering, therapeutic and research applications, both inside and outside the body,” says PhD student Reut Plen. “Since the 3D neural networks we created simulate innate properties of human brain tissues, they can be used as experimental “mini-brains” and serve as a model for the study of medicinal drugs, for investigating communication between tissues, and as a way to build artificial networks for interfaces between engineering and biological components. In addition, the model suggests an interesting prospect for injecting such a gel, which contains cells, in its liquid state, introducing it into the nervous system and organizing the cells into the correct structure with the assistance of magnetic forces. The advantage of using this method is that magnetic fields can affect cells located deep inside the body in a non-invasive manner,” adds Plen.
Inserting magnetic particles into cells, and into nerve cells in particular, raises questions regarding the safety of future medical applications.
“The issue of safety is important and we’ve devoted much thought and research into it,” Prof. Orit Shefi points out. “In the first step, we tested the effect of different particles on cell health in culture. In addition, we coated the magnetic particles with a biocompatible protein. The coating creates a buffer between the magnetic element and the cell and encourages penetration of the nanoparticles. Importantly, iron, the building block of the nanoparticle, exists naturally in the body so it isn’t a foreign substance. Additionally, the same gel with magnetic particles has been tested in our laboratory and found safe to use in animal models.”
The US Food and Drug Administration has already approved the use of magnetic nanoparticles for diagnostic and imaging purposes and in cases of severe injury. The steps taken by the Bar-Ilan research group create an opportunity to advance the technology for future clinical use.
“This is only the beginning,” say Shefi and Plen. “Our novel method of creating ‘mini-brains’ opens the door to finding solutions for various neurological impairments which will hopefully improve the quality of life of numerous patients.
Sequential fear generalization and network connectivity in trauma exposed humans with and without psychopathology
by Xi Zhu, Benjamin Suarez-Jimenez, Amit Lazarov, Sara Such, Caroline Marohasy, Scott S. Small, Tor D. Wager, Martin A. Lindquist, Shmuel Lissek, Yuval Neria in Communications Biology
Exposure to trauma can be life-changing — and researchers are learning more about how traumatic events may physically change our brains. But these changes are not happening because of physical injury, rather our brain appears to rewire itself after these experiences. Understanding the mechanisms involved in these changes and how the brain learns about an environment and predicts threats and safety is a focus of the ZVR Lab at the Del Monte Institute for Neuroscience at the University of Rochester, which is led by assistant professor Benjamin Suarez- Jimenez, Ph.D.
“We are learning more about how people exposed to trauma learn to distinguish between what is safe and what is not. Their brain is giving us insight into what might be going awry in specific mechanisms that are impacted by trauma exposure, especially when emotion is involved,” said Suarez-Jimenez, who began this work as a post-doctoral fellow in the lab of Yuval Neria, Ph.D., professor at Columbia University Irving Medical Center.
Their research, recently published in Communications Biology, identified changes in the salience network — a mechanism in the brain used for learning and survival — in people exposed to trauma (with and without psychopathologies, including PTSD, depression, and anxiety). Using fMRI, the researchers recorded activity in the brains of participants as they looked at different-sized circles — only one size was associated with a small shock (or threat). Along with the changes in the salience network, researchers found another difference — this one within the trauma-exposed resilient group. They found the brains of people exposed to trauma without psychopathologies were compensating for changes in their brain processes by engaging the executive control network — one of the dominate networks of the brain.
“Knowing what to look for in the brain when someone is exposed to trauma could significantly advance treatments,” said Suarez-Jimenez, a co-first author with Xi Zhu, PhD, Assistant Professor of Clinical Neurobiology at Columbia, of this paper. “In this case, we know where a change is happening in the brain and how some people can work around that change. It is a marker of resilience.”
The possibility of threat can change how someone exposed to trauma reacts — researchers found this is the case in people with post-traumatic stress disorder (PTSD), as described in a recent study in Depression & Anxiety. Suarez-Jimenez, his fellow co-authors, and senior author Neria found patients with PTSD can complete the same task as someone without exposure to trauma when no emotion is involved. However, when emotion invoked by a threat was added to a similar task, those with PTSD had more difficulty distinguishing between the differences.
The team used the same methods as the other experiment — different circle sizes with one size linked to a threat in the form of a shock. Using fMRI, researchers observed people with PTSD had less signaling between the hippocampus — an area of the brain responsible for emotion and memory — and the salience network — a mechanism used for learning and survival. They also detected less signaling between the amygdala (another area linked to emotion) and the default mode network (an area of the brain that activates when someone is not focused on the outside world). These findings reflect a person with PTSD’s inability to effectively distinguish differences between the circles.
“This tells us that patients with PTSD have issues discriminating only when there is an emotional component. In this case, aversive; we still need to confirm if this is true for other emotions like sadness, disgust, happiness, etc.,” said Suarez-Jimenez. “So, it might be that in the real-world emotions overload their cognitive ability to discriminate between safety, danger, or reward. It overgeneralizes towards danger.”
“Taken together, findings from both papers, coming out of a NIMH funded study aiming to uncover neural and behavioral mechanisms of trauma, PTSD and resilience, help to extend our knowledge about the effect of trauma on the brain,” said Neria, lead PI on this study. “PTSD is driven by remarkable dysfunction in brain areas vital to fear processing and response. My lab at Columbia and the Dr. Suarez-Jimenez lab at Rochester are committed to advance neurobiological research that will serve the purpose of development new and better treatments that can effectively target aberrant fear circuits.”
Suarez-Jimenez will continue exploring the brain mechanisms and the different emotions associated with them by using more real-life situations with the help of virtual reality in his lab. He wants to understand if these mechanisms and changes are specific to a threat and if they expand to context-related processes.
Oral microbes and the formation of cerebral abscesses: A single-centre retrospective study
by Holly Roy, Raul Bescos, Ewen McColl, Umar Rehman, Elizabeth Cray, Louise A. Belfield, King-David Nweze, Kevin Tsang, William Singleton, Peter Whitfield, Zoe Brookes in Journal of Dentistry
Bacteria known to cause oral infections may also be a contributory factor in patients developing potentially life-threatening abscesses on the brain, new research has shown.
The study, published in the Journal of Dentistry, investigated brain abscesses and their association with bacteria that occur in the oral cavity. While this type of abscess is relatively uncommon, it can result in significant mortality and morbidity.
Researchers examined the records of 87 patients admitted to the hospital with brain abscesses, and used microbiological data obtained from abscess sampling and peripheral cultures.
This allowed them to investigate the presence of oral bacteria in patients’ brain abscesses where a cause of the abscess had either been found, as was the case in just 35 patients or not found.
Their results showed that the 52 patients where no cause had been found were about three times as likely to have oral bacteria present in their samples.
Those patients also carried significantly higher counts of Streptococcus anginosus, a bacteria that can lead to pharyngitis, bacteremia, and infections in internal organs such as the brain, lung, and liver. This bacteria is often found in dental abscesses.
Writing in the study, researchers say the findings suggest that the oral cavity could be considered a source of infection in cases of brain abscess where no clear cause has been identified.
The research was led by the University of Plymouth and University Hospitals Plymouth NHS Trust.
Dr Holly Roy, an NIHR Clinical Lecturer in Neurosurgery based at the University of Plymouth and University Hospitals Plymouth NHS Trust, is the study’s lead author.
She said: “While many potential causes of brain abscesses are recognised, the origin of infection often remains clinically unidentified. However, it was still surprising to frequently find orally occurring bacteria in brain abscesses of unexplained origin. It highlights the importance of using more sensitive techniques to assess the oral cavity as a potential bacterial source in brain abscess patients. It also highlights the importance of improving dental care and oral hygiene more generally.”
The study forms part of ongoing research taking place within the University’s Oral Microbiome Research Group, led by Dr Raul Bescos and Dr Zoe Brookes, to explore the links between the oral microbiome and a range of cardiovascular and neurological conditions.
Other clinical trials are underway investigating the links between gum health and Alzheimer’s disease and identifying patients under high cardiovascular risk in primary care dental clinics, as an altered balance of oral bacteria (microbiome) during gum disease can lead to high blood pressure and strokes.
These clinical studies are being carried out in primary care dental facilities run by Peninsula Dental Social Enterprise, where the focus of the research is very much on improving clinical outcomes for patients.
Adaptive cellular response of the substantia nigra dopaminergic neurons upon age‐dependent iron accumulation
by Kujin Kwon, Hwapyeong Cho, Soyeon Lee, Eun Jeong Cho, Weonjin Yu, Catherine Yen Li Kok, Hyunsoo Shawn Je, Jae‐Ick Kim, Hyung Joon Cho, Taejoon Kwon in Aging Cell
Iron (Fe) accumulates in the brain cortex with aging. A plethora of studies indicate that progressive iron accumulation in the substantia nigra (SN) in the aged human brain is a major risk factor for Parkinson’s disease (PD) and other neurodegenerative diseases, but not everyone. This is because our body has plans to respond specifically to iron overloading.
A recent study, jointly led by Professor Taejoon Kwon and Professor Hyung Joon Cho in the Department of Biomedical Engineering at UNIST details the neuronal response to excessive iron accumulation, which is associated with age-related neurodegenerative diseases.
By investigating the response of neurons in the SN against age-related iron accumulation, the research team identified a transcriptome profile of aging-related iron accumulation using rats of different ages and confirmed their iron accumulation using the magnetic resonance images. With the additional animal experiments and cell line experiments, they found that two genes (CLU and HERPUD1) responded to age-related iron accumulation, and the knockdown of these genes severely impaired the cellular tolerance for iron toxicity.
“We conjecture that the understanding of the gene expression landscape during age-related iron accumulation can help us to elucidate molecular pathways and putative preventative strategies against neurodegenerative diseases,” noted the research team.
What You See Is What You Hear: Sounds Alter the Contents of Visual Perception
by Jamal R. Williams, Yuri A. Markov, Natalia A. Tiurina, Viola S. Störmer in Psychological Science
Perception generally feels effortless. If you hear a bird chirping and look out the window, it hardly feels like your brain has done anything at all when you recognize that chirping critter on your windowsill as a bird.
In fact, research in Psychological Science suggests that these kinds of audio cues can not only help us to recognize objects more quickly but can even alter our visual perception. That is, pair birdsong with a bird and we see a bird — but replace that birdsong with a squirrel’s chatter, and we’re not quite so sure what we’re looking at.
“Your brain spends a significant amount of energy to process the sensory information in the world and to give you that feeling of a full and seamless perception,” said lead author Jamal R. Williams (University of California, San Diego) in an interview. “One way that it does this is by making inferences about what sorts of information should be expected.”
Although these “informed guesses” can help us to process information more quickly, they can also lead us astray when what we’re hearing doesn’t match up with what we expect to see, said Williams, who conducted this research with Yuri A. Markov, Natalia A. Tiurina (École Polytechnique Fédérale de Lausanne), and Viola S. Störmer (University of California, San Diego and Dartmouth College).
“Even when people are confident in their perception, sounds reliably altered them away from the true visual features that were shown,” Williams said.
In their first experiment, Williams and colleagues presented 40 participants with figures that depicted two objects at various stages of morphing into one another, such as a bird turning into a plane. During this visual discrimination phase, the researchers also played one of two types of sounds: a related sound (in the bird/plane example, a birdsong or the buzz of a plane) or an unrelated sound like that of a hammer hitting a nail.
Participants were then asked to recall which stage of the object morph they had been shown. To show what they recalled, they used a sliding scale that, in the above example, made the object appear more bird or more plane-like. Participants were found to make their object-morph selection more quickly when they heard related (versus unrelated) sounds and to shift their object-morph selection to more closely match the related sounds that they heard.
“When sounds are related to pertinent visual features, those visual features are prioritized and processed more quickly compared to when sounds are unrelated to the visual features. So, if you heard the sound of a birdsong, anything bird-like is given prioritized access to visual perception,” Williams explained. “We found that this prioritization is not purely facilitatory and that your perception of the visual object is actually more bird-like than if you had heard the sound of an airplane flying overhead.”
In their second experiment, Williams and colleagues explored whether this effect was specific to the visual-discrimination phase of perceptual processing or, alternatively, if sounds might instead shape visual perception by influencing our decision-making processes. To do so, the researchers presented 105 participants with the same task, but this time they played the sounds either while the object morph was on screen or while participants were making their object-morph selection after the original image had disappeared.
As in the first experiment, audio input was found to influence participants’ speed and accuracy when the sounds were played while they were viewing the object morph, but it had no effect when the sounds were played while they reported which object morph they had seen.
Finally, in the third experiment with 40 participants, Williams and colleagues played the sounds before the object morphs were shown. The goal here was to test whether audio input may influence visual perception by priming people to pay more attention to certain objects. This was also found to have no effect on participants’ object-morph selections.
Taken together, these findings suggest that sounds alter visual perception only when audio and visual input occur at the same time, the researchers concluded.
“This process of recognizing objects in the world feels effortless and fast, but in reality it’s a very computationally intensive process,” Williams said. “To alleviate some of this burden, your brain is going to evaluate information from other senses.”
Williams and colleagues would like to build on these findings by exploring how sounds may influence our ability to locate objects, how visual input may influence our perception of sounds, and whether audiovisual integration is an innate or learned process.
Saccade vigor reflects the rise of decision variables during deliberation
by Colin C. Korbisch, Daniel R. Apuan, Reza Shadmehr, Alaa A. Ahmed in Current Biology
New research led by scientists at the University of Colorado Boulder suggests that eyes may really be the window to the soul — or, at least, how humans dart their eyes may reveal valuable information about how they make decisions.
The new findings offer researchers a rare opportunity in neuroscience: the chance to observe the inner workings of the human brain from the outside. Doctors could also potentially use the results to, one day, screen their patients for illnesses like depression or Parkinson’s Disease.
“Eye movements are incredibly interesting to study,” said Colin Korbisch, doctoral student in the Paul M. Rady Department of Mechanical Engineering at CU Boulder and lead author of the study. “Unlike your arms or legs, the speed of eye movements is almost totally involuntary. It’s a much more direct measurement of these unconscious processes happening in your brain.”
He and his colleagues, including researchers at Johns Hopkins University in Baltimore, published their findings in the journal Current Biology.
In the study, the team asked 22 human subjects to walk on a treadmill and then choose between different settings displayed on a computer screen: a brief walk up a steep grade or a longer walk on flat ground.
Researchers discovered that the subjects’ eyes gave them away: Even before they made their choices, the treadmill users tended to move their eyes faster when they looked toward the options they ended up choosing. The more vigorously their eyes moved, the more they seemed to prefer their choice.
“We discovered an accessible measurement that will tell you, in only a few seconds, not just what you prefer but how much you prefer it,” said Alaa Ahmed, senior author of the study and associate professor of mechanical engineering at CU Boulder.
Ahmed explained that how or why humans make choices (Tea or coffee? Dogs or cats?) is notoriously difficult to study. Researchers don’t have many tools that will easily allow them to peer inside the brain. Ahmed, however, believes that our eyes could provide a glimpse into some of our thought processes. She’s particularly interested in a type of movement known as a “saccade.”
“The primary way our eyes move is through saccades,” Ahmed said. “That’s when your eyes quickly jump from one fixation point to another.”
Quickly is the key word: Saccades usually take just a few dozen milliseconds to complete, making them faster than an average blink.
To find out if these darting motions give clues about how humans come to decisions, Ahmed and her colleagues decided to hit the gym.
In the new study, the team set up a treadmill on the CU Boulder campus. Study subjects exercised on various inclines for a period of time then sat down in front of a monitor and a high-speed, camera-based device that tracked their eye movements. While at the screen, they pondered a series of options, getting 4 seconds to pick between two choices represented by icons: Did they want to walk for 2 minutes at a 10% grade or for 6 minutes at a 4% grade? Once done, they returned to the treadmill to feel the burn based on what they chose.
The team found that subjects’ eyes underwent a marathon of activity in just a short span of time. As they considered their options, the individuals flitted their eyes between the icons, first slowly and then faster.
“Initially, the saccades to either option were similarly vigorous,” Ahmed said. “Then, as time passed, that vigor increased and it increased even faster for the option they eventually chose.”
The researchers also discovered that people who made the hastiest decisions — the most impulsive members of the group, perhaps — also tended to move their eyes more vigorously. Once the subjects decided on their pick, their eyes slowed again.
“Real-time read-outs of this decision-making process typically require invasive electrodes placed into the brain. Having this more easily measured variable opens a lot of possibilities,” Korbisch said.
Flicks of the eye could matter for a lot more than understanding how humans make decisions. Studies in monkeys, for example, have suggested that some of the same pathways in the brain that help primates pick between this or that may also break down in people with Parkinson’s — a neurological illness in which individuals experience tremors, difficulty moving and other issues.
“Slowed movements aren’t just a symptom of Parkinson’s but also appear in a lot of mental health disorders, such as depression and schizophrenia,” Ahmed said. “We think these eye movements could be something that medical professionals track as a diagnostic tool, a way to identify the progress of certain illnesses.”
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