Recent studies have shown that children with ASD who have language impairment have lower gray matter volume and greater gyrification in the temporal and frontal lobes of the cerebral cortex, which are crucial for language function.
Gray matter is the part of the brain that contains the cell bodies of neurons, while gyrification refers to the folding of the cerebral cortex. The cerebral cortex is the outer layer of the brain, and it is responsible for many of our cognitive functions, including language. The temporal and frontal lobes of the cerebral cortex are particularly important for language processing and production.
They found that the children with language impairment had lower gray matter volume in several regions of the cerebral cortex, including the temporal and frontal lobes.
Another study by Supekar et al. (2013) investigated the relationship between gyrification and language impairment in children with ASD. The researchers used MRI to measure gyrification in the brains of children with ASD who had language impairment and those who did not. They found that the children with language impairment had greater gyrification in several regions of the cerebral cortex, including the temporal and frontal lobes.
It is important to note that the relationship between brain structure and language impairment in children with ASD is complex and not fully understood. Some studies have found no differences in gray matter volume or gyrification between children with ASD who have language impairment and those who do not (e.g., Bigler et al., 2007). Other studies have found differences in other regions of the brain, such as the parietal lobe (e.g., Minshew et al., 2010).
Despite these inconsistencies, the findings of the studies mentioned above suggest that the temporal and frontal lobes of the cerebral cortex may be particularly important for language impairment in children with ASD. Further research is needed to better understand the relationship between brain structure and language impairment in this population, as well as to develop more effective interventions for improving language function in children with ASD.
A new study aimed to investigate the volumetric and surface-based parameters in school-aged children with ASD, compared to age- and sex-matched typically developing (TD) children, and to analyze the relationships between these parameters in the language-related brain areas and language impairment in children with ASD.
Whole-brain analysis showed alterations in multiple regions in children with ASD on both volume- and surface-based parameters. The comparison of total brain volume between ASD and TD groups of children showed a significant reduction of total GM volume in autistic children, with several brain regions in the right hemisphere differing between groups.
GM thickness was also significantly decreased in children with ASD in 27 regions of interest (ROIs) in both hemispheres, when comparing them to TD peers. These results are consistent with previous studies that have shown the reduction of both GM volume and thickness in school-aged children with ASD.
The list of 27 ROIs where GM thickness was significantly decreased in children with ASD may include:
- Prefrontal cortex
- Temporal lobe
- Parietal cortex
- Occipital cortex
- Cerebellum
- Hippocampus
- Amygdala
- Insula
- Striatum
- Thalamus
- Anterior cingulate cortex
- Posterior cingulate cortex
- Fusiform gyrus
- Superior temporal gyrus
- Inferior temporal gyrus
- Medial prefrontal cortex
- Orbitofrontal cortex
- Dorsolateral prefrontal cortex
- Ventromedial prefrontal cortex
- Precuneus
- Angular gyrus
- Supplementary motor area
- Postcentral gyrus
- Precentral gyrus
- Superior parietal lobule
- Inferior parietal lobule
- Broca’s area (inferior frontal gyrus)
It’s important to note that the specific regions where GM thickness was decreased in children with ASD may vary depending on the study and methodology used.
Other abnormalities in the surface morphology, such as atypical gyrification and cortical complexity, were also observed in children with ASD.
Gyrification index (GI) in the group of autistic children was higher in precentral and postcentral gyri and entorhinal cortex in the left hemisphere and in postcentral gyrus and inferior parietal lobule in the right hemisphere compared to TD children.
Gyrification Index (GI) is a measure of the amount of cortical folding or wrinkling in the brain. It is calculated by dividing the total surface area of the cortex by the area of a smooth or unfolded cortex, and is expressed as a ratio.
The gyrification of the brain is an important aspect of its structure and function, as it allows for more surface area within the skull, which in turn allows for more neurons and synapses. The process of gyrification occurs during fetal development and continues into early childhood, and is thought to be influenced by both genetic and environmental factors.
GI is typically measured using magnetic resonance imaging (MRI) scans of the brain. The MRI images are processed using specialized software that can detect and measure the amount of folding in the cortex. This is done by creating a three-dimensional model of the brain and using algorithms to identify the boundaries of the cortex.
Once the cortex is segmented from the MRI images, the surface area is calculated and compared to the surface area of a smooth or unfolded cortex. The ratio of these two values is the gyrification index. A higher GI indicates more cortical folding or wrinkling, while a lower GI indicates less folding.
GI has been used in a variety of studies to investigate the relationship between brain structure and function. For example, researchers have found that individuals with certain neurological and psychiatric disorders, such as schizophrenia and bipolar disorder, tend to have lower GI values in certain regions of the brain. Other studies have explored the relationship between GI and cognitive abilities, such as memory and attention, and have found that higher GI values are associated with better cognitive performance.
Overall, GI is a useful tool for understanding the structural organization of the brain and its relationship to various neurological and psychiatric conditions, as well as cognitive function.
In addition to the traditional method of calculating GI, which involves dividing the total cortical surface area by the area of a smooth or unfolded cortex, other methods have been developed to measure gyrification. These methods include the use of fractal dimensions and the measurement of local gyrification index (LGI) in specific regions of the brain.
Fractal dimensions are a way of measuring the complexity of an object, such as the surface of the brain. The fractal dimension of a surface can be calculated by analyzing the patterns of self-similarity across different scales. In the context of the brain, the fractal dimension can be used to quantify the amount and complexity of cortical folding.
LGI, on the other hand, is a measure of the amount of folding in specific regions of the brain. It is calculated by dividing the area of the cortical surface within a given region by the area of a smooth or unfolded surface within that same region. LGI values can be compared across different regions of the brain to identify patterns of folding that are specific to certain functions or behaviors.
Overall, GI and related measures of cortical folding are important tools for understanding the complex structure and function of the brain. While there is still much to be learned about the relationship between gyrification and cognition, these measures have already provided important insights into the neurobiology of a wide range of neurological and psychiatric disorders.
Remarkably, only GM volume in the left temporal cortex was associated with the severity of autistic symptoms, indicating that the higher GM volume was related to the greater severity of autism. This is in agreement with some studies that show temporal regions are usually related to social perception and communication in ASD.
The analysis of the relationships between volume- and surface-based parameters of language-related ROIs and language abilities of children with ASD revealed strong effects in GM thickness and gyrification. The results demonstrated that the pathological decrease of GM thickness in all language-related ROIs was associated with more severe language impairment.
The pathological increase of GI in all these ROIs was also related to more severe language impairment in ASD. GM and WM volumes as well as SD were not related to language abilities of these children in any language-related ROIs, and FD was significant only in temporal cortex.
Researchers have become increasingly interested in the potential neurological effects of COVID-19, including its impact on gray matter volume in the brain.
Gray matter volume is a crucial component of brain structure, and it plays a role in a wide range of cognitive functions, including memory, attention, and emotional regulation. Lower gray matter volume has been associated with a range of neurological and psychiatric disorders, including depression, anxiety, and schizophrenia.
Recent studies have suggested that COVID-19 may have an impact on gray matter volume in certain areas of the brain. For example, a study published in The Lancet Psychiatry in 2021 conducted magnetic resonance imaging (MRI) scans on individuals who had recovered from COVID-19 and found that they were more likely to have lower gray matter volume in specific brain regions compared to individuals who had not had COVID-19.
While the mechanisms underlying the impact of COVID-19 on gray matter volume are not yet fully understood, there are several potential explanations. One possibility is that the virus may directly invade the brain, leading to inflammation and damage to brain tissue. Another possibility is that the impact on gray matter volume may be related to other factors associated with COVID-19, such as the systemic inflammation and immune response triggered by the virus. Additionally, the stress and anxiety associated with the pandemic may also play a role in brain changes, including alterations in gray matter volume.
The implications of lower gray matter volume in the brain due to COVID-19 are still unclear. However, changes in gray matter volume could potentially impact cognitive functions and contribute to long-term neurological consequences in individuals who have had COVID-19. Some individuals who have recovered from COVID-19 have reported ongoing symptoms, such as brain fog, fatigue, and memory problems, which may be related to changes in gray matter volume in the brain.
It is important to note that not all individuals who have had COVID-19 may experience changes in gray matter volume, and the severity of the virus and the presence of other risk factors may also play a role. Additionally, the studies conducted so far have focused on individuals who have recovered from COVID-19, and it is unclear whether similar changes in gray matter volume may be observed in individuals with mild or asymptomatic cases, or in those who are still actively infected with the virus.
As the pandemic continues, it is important for researchers to continue investigating the potential impact of COVID-19 on gray matter volume in the brain. Further research is needed to fully understand the mechanisms underlying these potential changes in brain structure, as well as their long-term implications. Understanding the impact of COVID-19 on gray matter volume may have important implications for the management and care of individuals who have been affected by the virus, and further research in this area is warranted to shed more light on this emerging topic.
In conclusion, this study shows that atypical patterns of brain development exist in school-aged children with ASD, reflected in both volume- and surface-based morphology. The abnormalities in the surface morphology, particularly in GM thickness and gyrification, in language-related ROIs are associated with language impairment in these children.
The findings of this study have important implications for understanding the neurobiology of language impairment in children with ASD and may inform the development of targeted interventions to improve language functioning in this population.
reference link :
https://www.nature.com/articles/s41598-023-28463-w#Sec29
