The organoids contained an array of neural and other cell types found in the cerebral cortex, the outer most layer of the brain involved in language, emotion, reasoning, and other high-level mental processes. CREDIT Yueqi Wang

Whatever you do, don’t call them “mini-brains,” say University of Utah Health scientists. Regardless, the seed-sized organoids—which are grown in the lab from human cells—provide insights into the brain and uncover differences that may contribute to autism in some people.

“We used to think it would be too difficult to model the organization of cells in the brain,” says Alex Shcheglovitov, PhD, assistant professor of neurobiology at U of U Health. “But these organoids self-organize. Within a few months, we see layers of cells that are reminiscent of the cerebral cortex in the human brain.”

The research describing the organoids and their potential for understanding neural diseases publishes in Nature Communicationson Oct 6with Shcheglovitov as senior author and Yueqi Wang, PhD, a former graduate student in his lab, as lead author. They carried out the research with postdoctoral scientist Simone Chiola, PhD, and other collaborators at the University of Utah, Harvard University, University of Milan, and Montana State University.

Investigating autism

Having the ability to model aspects of the brain in this way gives scientists a glimpse into the inner workings of a living organ that is otherwise nearly impossible to access. And since the organoids grow in a dish, they can be tested experimentally in ways that a brain cannot.

Shcheglovitov’s team used an innovative process to investigate effects of a genetic abnormality associated with autism spectrum disorder and human brain development. They found that organoids engineered to have lower levels of the gene, called SHANK3, had distinct features.

Even though the autism organoid model appeared normal, some cells did not function properly:

• Neurons were hyperactive, firing more often in response to stimuli,
• Other signs indicated neurons may not efficiently pass along signals to other neurons,
• Specific molecular pathways that cause cells to adhere to one another were disrupted.

These findings are helping to uncover the cellular and molecular causes of symptoms associated with autism, the authors say. They also demonstrate that the lab-grown organoids will be valuable for gaining a better understanding of the brain, how it develops, and what goes wrong during disease.

“One goal is to use brain organoids to test drugs or other interventions to reverse or treat disorders,” says Jan Kubanek, PhD, a co-author on the study and an assistant professor of biomedical engineering at the U.

Building a better brain model

Scientists have long searched for suitable models for the human brain. Lab-grown organoids are not new, but previous versions did not develop in a reproduceable way, making experiments difficult to interpret.

To create an improved model, Shcheglovitov’s team took cues from how the brain develops normally. The researchers prompted human stem cells to become neuroepithelial cells, a specific stem cell type that forms self-organized structures, called neural rosettes, in a dish. Over the course of months, these structures coalesced into spheres and increased in size and complexity at a rate similar to the developing brain in a growing fetus.

After five months in the lab, the organoids were reminiscent of “one wrinkle of a human brain” at 15 to 19 weeks post-conception, Shcheglovitov says. The structures contained an array of neural and other cell types found in the cerebral cortex, the outermost layer of the brain involved in language, emotion, reasoning, and other high-level mental processes.

Like a human embryo, organoids self-organized in a predictable fashion, forming neural networks that pulsated with oscillatory electrical rhythms and generated diverse electrical signals characteristic of a variety of different kinds of mature brain cells.

“These organoids had patterns of electrophysiological activity that resembled actual activity in the brain. I didn’t expect that,” Kubanek says. “This new approach models most major cell types and in functionally meaningful ways.”

Shcheglovitov explains that these organoids, which more reliably reflect intricate structures in the cortex, will allow scientists to study how specific types of cells in the brain arise and work together to perform more complex functions.

“We’re beginning to understand how complex neural structures in the human brain arise from simple progenitors,” Wang says. “And we’re able to measure disease-related phenotypes using 3D organoids that are derived from stem cells containing genetic mutations.”

He adds that using the organoids, researchers will be able to better investigate what happens at the earliest stages of neurological conditions, before symptoms develop.

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Visit UBrain browser to visualize the cells and electrical responses detected in organoi

There is a large overlap between the genetic causes of autism and ADHD. Now, researchers from Aarhus University have found gene variants, which increase the risk of developing only one of the diagnoses and not the other.

In the group of neurodevelopmental disorders, ADHD and autism have several things in common: They are two of the most common child psychiatric diagnoses, both diagnoses are highly heritable, and although they differ from each other in the core signs , autism and ADHD have a significant overlap in their underlying genetic causes.

Researchers have now identified seven genetic variants that are common to both autism and ADHD, as well as five gene variants that are specific to only one of the two diagnoses.

“We have succeeded in identifying both shared genetic risk variants and genetic variants that differentiate the two developmental disorders,” says Professor Anders Børglum of the Department of Biomedicine at Aarhus University and iPSYCH, Denmark’s largest research project within psychiatry, which is behind the study.

“That means that we are beginning to understand both the biological processes behind the development of both diagnoses, and – as something completely new – also the processes that push the developmental disorder specifically in the direction of either autism or ADHD.”

What happens in the brain?

The genetic variants affect nerve cells in the brain and the way the brain develops and communicates. It is also remarkable that some of the genetic variants identified also impact people’s cognitive functions in general in the population.

Specifically, the researchers can, for example, see that some of the genetic variants that only increase the risk of autism also increase the cognitive functions of individuals, while the complementary variants, which only increase the risk of ADHD, generally reduce the cognitive functions of individuals.

Similarly, the researchers have identified a gene variant that increases the risk of autism and, simultaneously, reduces the volume of a specific brain area in people in the general population. In contrast, the complementary variant increases the risk of ADHD and increases the volume of this brain area.

Altered diagnostic guidelines

It may seem obvious, but the study is the first in the world to show that people with both ADHD and autism are double-burdened with a genetic risk of receiving both diagnoses. In contrast, people who only have one of the diagnoses, for the most part, only bear the genetic risk variants for this condition.

“This means, for example, that people with both diagnoses have an equally large load of ADHD genetic factors as people who only have ADHD, and at the same time the same large load of autism genetic factors as people who only have autism. So it makes very good biological sense that some people have both diagnoses,” says Anders Børglum.

The researchers analyse large datasets of genetic profiles to learn more about diseases and developmental disorders. This can make it possible to create more precise diagnoses and earlier interventions, and ensure that the individual patient receives the right treatment.

“The autism diagnosis is typically made before an ADHD diagnosis. So if, for example, the person is also hyperactive and finds it difficult to concentrate, this may be slightly drowned out by the autism symptoms, and we may not see the ADHD challenges,” explains Anders Børglum.

“But if we have a genetic study of a person with an autism diagnosis, and we see a major genetic load ADHD genetics, then it may be that we should monitor that person more closely. In this way, we can, in the future, become quicker to spot the development and give the family good tools to handle this diagnosis, too. “

A few years ago – due to an official diagnosis hierarchy – it was not in principle possible to diagnose ADHD in a person with autism, he says.

“But now we have shown that people with both diagnoses are double burdened with the genetic risk of both developmental disorders. There is thus a clear biological difference between whether you have both diagnoses, or just one. The study is, therefore a strong biological argument for the revised diagnostic guidelines, e.g. in the American Diagnosis and Classification system for Mental Disorders (DSM-5), where it is now possible for the same person to receive both diagnoses,” says Anders Børglum.

“This is the first step. Here and now, the study is relevant because it helps to create a better understanding of the causes of the two developmental disorders, and in the long term, this can form the basis for better diagnostics and treatment.”

In the decades since the “clinical” definitions of autism in the 1980s, many have been advocating for understanding autism as a normal part of the neurodiversity spectrum rather than as a “problem” to be “fixed.” Still, in the research literature, autism is often described using medical or pathologizing language. To make autism research less harmful to the autistic community, researchers publishing in the journal Trends in Neurosciences on September 29 lay out a data-driven guide for how scientists and researchers should talk about autism in their work.

“The evolution in the understanding of autism has also mirrored a transition in the use of language in research contexts,” write the authors. “Historically, most autism research has been carried out without input from autistic people. This research has often described autism and autistic people using medicalized, pathologizing, and deficit-based language (e.g., disorder, impairment, cure) and person-first language (e.g., child with autism).”

The paper was authored by Ruth Monk, an autistic researcher at University of Auckland in New Zealand; Andrew Whitehouse, an autism researcher at the Telethon Kids Institute and professor at The University of Western Australia; and Hannah Waddington, a senior lecturer in educational psychology at Victoria University of Wellington, New Zealand.

The authors offer a table of potentially offensive language and preferred alternatives, compiled from several large surveys of autistic community members.

For example, “Autism Spectrum Disorder” should be replaced with “autism”; “person with autism” replaced with “autistic person”; “normal” replaced with “allistic” or “non-autistic”; and “co-morbidity” with “co-occurring.”

“Autistic people have the most intimate autism expertise through their first-hand lived experience,” the authors write. “Thus, there is increasingly widespread acknowledgement that the terminology used to refer to autism and autistic people should prioritize the perspectives and preferences of autistic people themselves. These preferences been explored by several large surveys conducted by researchers and autistic advocates.”

The authors also advocate for a shift in the way autism research is conducted. “Specifically,” they write, “the increasing use of participatory and co-produced research aims to reduce power imbalance between the researcher and the autistic community and to ensure that autistic people are involved throughout the research process.”

Randy Blakely, Ph.D., professor of biomedical science in FAU’s Schmidt College of Medicine and executive director of the FAU Stiles-Nicholson Brain Institute. CREDIT Florida Atlantic University

The prevalence, age of onset, and clinical symptoms for virtually all neuropsychiatric disorders differ between men and women. Among the disorders with pronounced sex bias are Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD), where the ratio of males/females diagnosed is approximately 4 to 1. Whether this skewed ratio arises from roles played in brain development by sex-specific DNA sequences or hormones or reflects the way that biological mechanisms and environmental influences elicit behavioral patterns differently in males and females, remains an area of open investigation.

Regardless of origin, altered behavior in these disorders signals a change in the function of key brain circuits wired up during development, refined throughout life, and coordinated through the actions of brain chemicals called neurotransmitters. One vital neurotransmitter that plays a key role in the behaviors altered by both ADHD and ASD is dopamine, whose powerful actions support motor initiation and coordination, motivation, reward and social behavior, as well as attention and higher cognitive function. Although dopamine-sensitive brain circuits engaged in these processes have been under scrutiny for decades, and in the case of ADHD, are the target of medications such as Adderall® and Ritalin®, the intrinsic sex-dependent differences in these pathways that could guide more precise diagnoses and treatments have only recently begun to be elucidated.

To better understand how dopamine levels at brain synapses are managed, neuroscientists from Florida Atlantic University, along with collaborators at the University of North Dakota School of Medicine and Health Sciences, have now added a significant piece to this puzzle by establishing key differences in the molecular dopamine disposal machinery in the brains of male and female mice.

The new research published in the journal Molecular Psychiatryand led by Randy Blakely, Ph.D., professor of biomedical science in FAU’s Schmidt College of Medicine and executive director of the FAU Stiles-Nicholson Brain Institute, provides new insight into how sex determines the mechanisms by which distinct synapses monitor and regulate dopamine signaling. Moreover, the impact the sex differences described is particularly pronounced when the mice express a human genetic variant found in boys with either ADHD or ASD.  

“Often, due to assumptions that sex hormone variation will cloud data interpretations, and that use of one sex will cut animal use and costs in half without a loss of key insights, many researchers using animal models to study brain disorders work chiefly with males, even more reasonable when modeling disorders that exhibit male bias,” said Blakely.  

In a prior study, looking for genetic changes in dopamine regulatory genes in children with ADHD, Blakely and his team identified a gene variant that alters the function of the dopamine transporter (DAT) in a peculiar way. Normally DAT acts to remove dopamine from synapses, acting like a nanoscale dopamine vacuum cleaner. When the DAT variant was expressed in cells, however, it “ran backward,” spitting out dopamine rather than efficiently removing it. After engineering the variant into the genome of mice, Blakely’s team found changes in behavior and drug responses predicted by this anomalous DAT behavior, with an emphasis on traits linked to pathways related to locomotor activation, habitual behavior and impulsivity. Notably, these studies were performed exclusively with male mutant mice.

Blakely and Adele Stewart, Ph.D., first author on the report, a research assistant professor of biomedical science in FAU’s Schmidt College of Medicine and a member of the FAU Stiles-Nicholson Brain Institute, recognized there was more to be done, particularly with respect to how females would handle the mutation. Would the DAT mutation impact the same brain regions and behaviors in females as it had done in males? The answer is a resounding no. Females show effects of the mutation in brain regions unaffected in males and vice versa. Further work revealed that this switch is due to a circuit flip in how brain pathways in males and females use a key DAT regulator protein to magnify the backwards activity of the transporter.

The behavioral consequences of this region-specific, sex-biased pattern of DAT regulation are profound, with the mutant DAT altering behaviors in a pattern unique to each sex. For example, mutant females appeared more anxious and had issues with novelty recognition compared to wildtype females. Males on the other hand are less social and display increased perseverative behavior, changes not seen in females.

“Our work clearly shows that the female mutant DAT mice are not ‘protected’ from the impact of the mutation, but rather, exhibit a unique set of behavioral changes linked to an ingrained, sex-biased architecture of the dopamine system,” said Stewart. “The same variant also has been found in two unrelated boys with ASD, a disorder that often also displays comorbid ADHD.”

Interestingly, the only reported clinical occurrence of the DAT variant in a female involved a diagnosis of bipolar disorder (BPD). Both the mania and depression associated with BPD have been suggested to be linked to altered dopamine signaling. Blakely’s group also has reported high impulsivity traits in a female carrier of the same mutation studied in this latest paper, suggesting that overlap of traits linked to dopamine can also occur between the sexes, or perhaps the forms of impulsivity (e.g. waiting versus action) may be involved.

A “resilience” framework often is used to explain discrepancies in the sex bias observed in neuropsychiatric disorders. However, recent evidence suggests that sex bias can be due, at least in part, to differences in symptomology and associated comorbidities and the resultant failure of current diagnostic instruments to assure identification of the same disorder in both sexes.

“While we understand that there are biological differences between rodent and human brains, studies like ours provide an important opportunity to explore biological mechanisms that contribute to sex differences in risk for neuropsychiatric diseases,” said Stewart. “What our study shows is that behavioral generalizations across the sexes may limit diagnosis of mental illness, particularly if one sex translates alterations into outward signs such as  hyperactivity and aggression versus more internal manifestations such as learning, memory and mood, even when the same molecular pathology is at work. What is more, our work supports the idea that treatment strategies should be cognizant of the sex-dependence of neuronal signaling mechanisms rather than assuming treatment that what is good for the goose is good for the gander. In fact, such therapies may either not be good for the gander at all, or good for a completely different kind of disorder.”

The research provides a clear example of how genetic changes can have sex-dependent effects on physiology and behavior, depending on whether other co-regulatory genes are naturally expressed by the same cells.

“Because the basis for the differential response to the DAT mutation is the presence or absence of DAT regulation in these two areas, the implications do not just apply to the few individuals with the genetic variant nor are limited to ADHD and ASD,” said Blakely. “Investigators exploring other disorders linked to altered dopamine signaling should consider whether the mechanism we have uncovered could drive sex-dependent features of these diseases. By extension, we now need to consider whether the mechanism we have uncovered contributes to sex-dependent ways in which dopamine signaling drives normal behavior.”   

Researchers at the Del Monte Institute for Neuroscience at the University of Rochester have expanded the understanding of how the brain is engaged during complex audiovisual speech perception. The study now out in NeuroImage, describes how listening and watching a narrator tell a story activates an extensive network of brain regions involved in sensory processing, multisensory integration, and cognitive functions associated with the comprehension of the story content. Understanding the involvement of this larger network has the potential to give researchers new ways to investigate neurodevelopmental disorders.

“Multisensory integration is an important function of our nervous system as it can substantially enhance our ability to detect and identify objects in our environment,” said Lars Ross, Ph.D., research assistant professor of Imaging Sciences and Neuroscience and first author of the study. “A failure of this function may lead to a sensory environment that is perceived as overwhelming and can cause a person to have difficulty adapting to their surroundings, a problem we believe underlies symptoms of some neurodevelopmental disorders such as autism.”

Using fMRI, researchers examined the brain activity of 53 participants as they watched a video recording of a speaker reading “The Lorax.” How the story was presented would change randomly in one of four ways – audio only, visual only, synchronized audiovisual, or unsynchronized audiovisual. Researchers also monitored the participants’ eye movements. They found that along with the previously identified sites of multisensory integration, viewing the speaker’s facial movements also enhanced brain activity in the broader semantic network and extralinguistic regions not usually associated with multisensory integration, such as the amygdala and primary visual cortex. Researchers also found activity in thalamic brain regions which are known to be very early stages at which sensory information from our eyes and ears interact.

“This suggests many regions beyond multisensory integration play a role in how the brain processes complex multisensory speech – including those associated with extralinguistic perceptual and cognitive processing,” said Ross.

Researchers designed this experiment with children in mind, according to the investigators who have already begun working with both children and adults on the autism spectrum in an effort to gain insight into how their ability to process audiovisual speech develops over time.

“Our lab is profoundly interested in this network because it goes awry in a number of neurodevelopmental disorders,” said John Foxe, Ph.D., lead author of this study. “Now that we have designed this detailed map of the multisensory speech integration network, we can ask much more pointed questions about multisensory speech in neurodevelopmental disorders, like autism and dyslexia, and get at the specific brain circuits that might be impacted.”