Category: Neurology

Categories : Neurology Obstetrics & GynaecologyTags :

Brain ‘Rewired’ by Sound Early in the Womb

On By ModernMedia

Playing music to foetuses in the womb to enhance their brain development is a popular practice even if thus far not grounded in science, but new research has shown that there may be some effect even at very early stages.

New research from John Hopkins University indicates that ‘wiring changes’ made in response to sounds occur even earlier than thought before. The ear canals of newborn mice only open after 11 days, while in humans, the ear canals open at 20 weeks’ gestation. The researchers used the mice as a model for human foetuses, and examined their neural connections at one week old.

“As scientists, we are looking for answers to basic questions about how we become who we are,” said Patrick Kanold, PhD, professor of biomedical engineering at The Johns Hopkins University and School of Medicine. “Specifically, I am looking at how our sensory environment shapes us and how early in foetal development this starts happening.”

Prof Kanold started out in electrical engineering before switching to neuroscience. His field of research is on the cortex, the outer layer of neurons underneath which lies the white matter which consists of connective neurons.

In developing foetuses, in the white matter, subplate neurons can be found at 12 weeks in human gestation and the second embryonic week in mice. This subplate neurons are the precursors to neurons and die off over a period lasting from before birth to several months old. Before they disappear, they make a connection between the thalamus, which is an important sensory gateway, and the middle layers of the cortex.

“The thalamus is the intermediary of information from the eyes, ears and skin into the cortex,” explained Prof Kanold. “When things go wrong in the thalamus or its connections with the cortex, neurodevelopmental problems occur.”

The subplate neurons respond to sound before the cortical neurons, prompting two questions for Prof Kanold: When sound signals reach the subplate neurons, does anything happen, and can a change in sound signals reflect changes in the brain circuits at these young ages?

To answer these questions, the researchers used mice genetically engineered to be deaf, unable to convert sound into nerve signals. In deaf, week-old mice, there were 25-30% more connections between subplate and cortical neurons.

“When neurons are deprived of input, such as sound, the neurons reach out to find other neurons, possibly to compensate for the lack of sound,” said Prof Kanold. “This is happening a week earlier than we thought it would, and tells us that the lack of sound likely reorganises connections in the immature cortex.”

To compare the difference extra auditory stimuli made, the researchers put 2-day old pups in a quiet enclosure or an enclosure with a constant beeping sound. There were differences between the subplate neuron connections for beeping and quiet enclosure mice, but not as great as between the deaf and hearing mice. The quiet enclosure mice had stronger connections between the subplate and cortical neurons, similar to the deaf mice. The mice in the beeping enclosure also had a greater diversity in neural circuitry.

“In these mice we see that the difference in early sound experience leaves a trace in the brain, and this exposure to sound may be important for neurodevelopment,” explained Prof Kanold.

The researchers are planning to examine how sound in early development impacts the brain in later life, as well as how sounds in the womb influences neural wiring. This has application for cochlear implants for children born deaf. They also plan to study premature infants neural wiring problems and develop biomarkers for abnormal subplate neuron development. 

Source: Medical Xpress

Journal information: Early peripheral activity alters nascent subplate circuits in the auditory cortex, Science Advances (2021). DOI: 10.1126/sciadv.abc9155

Categories : Gender Mental Health NeurologyTags :

Women are Better ‘Mind Readers’ Than Men, Study Finds

On By ModernMedia

Women are better at ‘reading minds’ than men, finds a new study aimed at better understanding social interaction and the challenges faced by people with autism. 

Sometimes known in the field of psychology as ‘mentalising‘, the process is when people try to ascertain what others are really thinking, for example when they are sarcastic or even lying. Mind-reading has some basis in neuroscience: for example, some research indicates that sensitivity to social interactions is associated with the posterior superior temporal sulcus, an area of the brain which is also known to process biological motion. Everybody has some proficiency with mind reading, and some are inherently better than others. However, some lack the ability to a point where it becomes difficult to function in society, for example in autism.

The study made use of a self-report questionnaire asking participants to rate how well, for example, they could relate to others. It used four questions, each with ratings from one to four, giving a maximum total score of 16. The researchers determined that women scored higher than men on the questionnaire, and also confirmed the challenges reported by those with autism. 

Senior author Dr Punit Shah, at the University of Bath’s Department of Psychology explained: “We will all undoubtedly have had experiences where we have felt we have not connected with other people we are talking to, where we’ve perceived that they have failed to understand us, or where things we’ve said have been taken the wrong way. Much of how we communicate relies on our understanding of what others are thinking, yet this is a surprisingly complex process that not everyone can do.”

Dr Shah emphasised that there is a different between mind-reading and empathy, saying: “Mind-reading refers to understanding what other people are thinking, whereas empathy is all about understanding what others are feeling. The difference might seem subtle but is critically important and involves very different brain networks. By focussing carefully on measuring mind-reading, without confusing it with empathy, we are confident that we have just measured mind-reading. And, when doing this, we consistently find that females reported greater mind-reading abilities than their male counterparts.”

Lead researcher, Rachel Clutterbuck, emphasised the clinical importance of the questionnaire. She said: “This new test, which takes under a minute to complete, has important utility in clinical settings. It is not always obvious if someone is experiencing difficulties understanding and responding to others—and many people have learnt techniques which can reduce the appearance of social difficulties, even though these remain.

“This work has great potential to better understand the lived experience of people with mind-reading difficulties, such as those with autism, whilst producing a precise quantitative score that may be used by clinicians to identify individuals who may benefit from interventions.”

Dr Shah added that this study was about helping to understand mind-reading capabilities, and had created a freely available questionnaire for other efforts in this regard.

Source: Medical Xpress

Journal information: Rachel A. Clutterbuck et al, Development and validation of the Four-Item Mentalising Index., Psychological Assessment (2021). DOI: 10.1037/pas0001004

Categories : NeurologyTags :

Geometric Model of Sherlock Episode Reveals How We Recall Events

On By ModernMedia

Using a TV episode and a geometrical model, researchers at Dartmouth have come up with a new way to understand how the brain evaluates which experiences to store as memories and which to discard.

The researchers based their study around participants’ recall of a BBC episode of Sherlock against a geometric model of the events that happened in it. Their results allowed new insights into how memories are stored and then related to others.

Senior author Jeremy R Manning, an assistant professor of psychological and brain sciences, and director of the Contextual Dynamics Lab at Dartmouth, explained: “When we represent experiences and memories as shapes, we can use the tools provided by the field of geometry to explore how we remember our experiences, and to test theories of how we think, learn, remember, and communicate.

“When you experience something, its shape is like a fingerprint that reflects its unique meaning, and how you remember or conceptualise that experience can be turned into another shape. We can think of our memories like distorted versions of our original experiences. Through our research, we wanted to find out when and where those distortions happen (i.e. what do people get right and what do people get wrong), and examine how accurate our memories of experiences are.”

Using a public dataset of brain recordings from 17 participants who had viewed the same Sherlock episode and described what had happened. This dataset also contained detailed notes on what took place in that episode. They took these notes to create a list of 32 topics, which were then represented as a 32-dimensional model. Visualised in 2 dimensions, a dot-to-dot shape emerges, to which the shapes made by the participants’ recall of events can be compared.

Using the episode’s shape as a structure, they were able to see at what points the participants’ memories matched the episode, and what points they forgot or had distorted recollections. The shape also featured extraneous elements of fine detail, like architectural embellishments such as carvings, which reflected low-conceptual details. Some participants accurately recounted these low-conceptual details while others could only recall high-level plot points.

“One of our most intriguing findings was that, as people were watching the episode, we could use their brain activity patterns to predict the distorted shapes that their memories would take on when they recounted it later,” explained Manning. “This suggests that some of the details about our ongoing experiences get distorted in our brains from the moment they are stored as new memories. Even when two people experience the same physical event, their subjective experiences of that event start to diverge from the moment their brains start to make sense of what happened and distill that event into memories.”

These findings could be used as the basis for research into improving educational delivery, as well as patients’ understanding of matters explained to them by their doctors.

Source: Medical Xpress

Journal information: Geometric models reveal behavioural and neural signatures of transforming experiences into memories, Nature Human Behavior (2021). DOI: 10.1038/s41562-021-01051-6

Categories : Neurology PaediatricsTags :

No Evidence for Strep Exacerbating Chronic Tics in Kids

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A new study has found that children with chronic tic disorders, mainly Tourette syndrome, do not have tic exacerbations when exposed to group A Streptococcus.

No significant association with tic exacerbations emerged across four definitions of pharyngeal strep exposure with a mean follow-up of 16 months, though a weak link was observed in trend, reported Davide Martino, MD, PhD, of the University of Calgary, and co-authors.

Strep was however significantly associated with longitudinal changes in hyperactivity-impulsivity symptom severity of 17% to 21%.
“The link between Streptococcus and tics in children is still a matter of intense debate,” Martino stated. “We wanted to look at that question, as well as a possible link between strep and behavioral symptoms like obsessive-compulsive disorder and attention deficit hyperactivity disorder.

“While our findings suggest that strep is not likely to be one of the main triggers for making tics worse, more research is needed into other possible explanations. For example, the social stress of having this disorder could be implicated in making tics worse more than infections. It’s also possible another pathogen might be triggering an immune response associated with tic worsening.”

In an invited editorial, Andrea Cavanna, MD, PhD, of the University of Birmingham, and Keith Coffman, MD, of Children’s Mercy Hospital in Kansas City, observed that group A Streptococcus had been posited as a potential environmental factor in tic disorders for the past two decades.

The editorialists noted that, on the basis of isolated clinical observations, tic disorders should be included as a collateral feature in conditions which are known as pediatric autoimmune neuropsychiatric disorders associated with Streptococcus (PANDAS) infections. However, the results of longitudinal clinical studies were inconclusive, with a case control study even arguing against the association.

Drawing data from the EMTICS study, recruiting children with chronic tic disorders from 2013 to 2016, one arm of the study prospectively examined associations between new group A Streptococcus throat exposures and tic exacerbations, obsessive-compulsive disorder (OCD), and attention deficit hyperactivity disorder (ADHD) symptoms.

Four definitions of strep exposure were used: new definite (newly positive throat swab regardless of serological results), new possible (elevated anti-streptolysin O [ASOT] or anti-DNAseB [ADB] titers with negative or no throat swab), ongoing definite, and ongoing possible.

Initially, 59 children had a positive throat swab; as the study progressed, 103 children had new definite strep exposure. During follow-up, 308 children (43%) had tic exacerbations. The proportion of exacerbations temporally associated with strep exposure ranged from 5.5% to 12.9%, depending on exposure definition. No association between OCD symptoms and strep exposure was seen.

“Our study of the largest prospective cohort of youth with chronic tic disorders ever documented to date provides evidence against a temporal association between group A Streptococcus exposure and clinically relevant tic exacerbations,” the researchers wrote.

“This result indicates that specific diagnostic work-up or active management of group A Streptococcus infections in the context of worsening of tic severity in patients with chronic tic disorders is not warranted,” the researchers added.

The researchers noted that limitations included the data being collected from specialist centres in different countries, and that some cases of strep may have been missed.

Source: MedPage Today

Journal information (article): Martino D, et al “Association of Group A Streptococcus Exposure and Exacerbations of Chronic Tic Disorders: A Multinational Prospective Cohort Study” Neurology 2021; DOI: 10.1212/WNL.0000000000011610.

Journal information (editorial): Cavanna A, Coffman K “Streptococcus and Tics: Another Brick in the Wall?” Neurology 2021. DOI: 10.1212/WNL.0000000000011608.