Posts tagged cortical thickness
Articles and news from the latest research reports.
Institutional Rearing May Increase Risk for Attention-Deficit Disorder by Altering Cortical Development
Over the past decades, we have seen numerous tragic examples where the failure of institutions to meet the needs of infants for social contact and stimulation has led to the failure of these infants to thrive.
Infancy and childhood are critical life periods that shape the development of the cortex. A generation of research suggests that enriched environments, full of interesting stimuli to explore, promote cortical development and cognitive function. In contrast, deprivation and stress may compromise cortical development and attenuate some cognitive functions.
Young children who are raised in environments of psychosocial neglect, such as those who grow up in institutions for orphaned or abandoned children, are at markedly elevated risk for developing a wide range of mental health problems, including attention-deficit/hyperactivity disorder (ADHD).
Now, new data from the Bucharest Early Intervention Project (BEIP), published in the current issue of Biological Psychiatry, suggests that this type of deprived early environment is associated with drastic changes in brain development in children.
BEIP is a longitudinal study that has followed a sample of children raised from early infancy in institutions in Romania. The authors of the current report used data from 58 of those children and compared it with 22 typically-reared children from the same community. All children underwent a structural imaging scan and were assessed for symptoms of ADHD.
The researchers discovered that children raised in institutional settings exhibited widespread reductions in cortical thickness in multiple brain regions including the prefrontal, parietal, and temporal cortices relative to children raised in families in the community.
The data also revealed that the reduced cortical thickness in several of those same brain regions was associated with greater ADHD symptoms of inattention and impulsivity.
This is consistent with previous research that has implicated those brain regions in regulating attention, memory, and other vital cognitive processes.
"Perhaps most importantly, the new findings indicate that the high rates of ADHD among children raised in these deprived environments are explained, in part, by these atypical patterns of brain development," explained first author Dr. Katie McLaughlin, Assistant Professor at the University of Washington.
"These disturbing data provide a mechanism that links institutional rearing to compromised cortical development," said Dr. John Krystal, Editor of Biological Psychiatry. “They suggest that society may have to choose between investing in enriching institutional environments and enhancing the capacity of these institutions to offer mental health support on the one hand and bearing the cost of ADHD and its impact on social and vocational productivity on the other.”
McLaughlin agrees and added, “The early caregiving environment has lasting effects on brain development in children. Identifying strategies for mitigating these effects is critical for improving mental health and educational outcomes among children raised in deprived environments.”
(Source: elsevier.com)
Brain Development in Schizophrenia Strays from the Normal Path
Schizophrenia is generally considered to be a disorder of brain development and it shares many risk factors, both genetic and environmental, with other neurodevelopmental disorders such as autism and intellectual disability.
The normal path for brain development is determined by the combined effects of a complex network of genes and a wide range of environmental factors.
However, longitudinal brain imaging studies in both healthy and patient populations are required in order to map the disturbances in brain structures as they emerge, i.e., the disturbed trajectories of brain development.
A new study by an international, collaborative group of researchers has measured neurodevelopment in schizophrenia, by studying brain development during childhood and adolescence in people with and without this disorder. With access to new statistical approaches and long-term follow-up with participants, in some cases over more than a decade, the researchers were able to describe brain development patterns associated with schizophrenia.
"Specifically, this paper shows that parts of the brain’s cortex develop differently in people with schizophrenia," said first author Dr. Aaron F. Alexander-Bloch, from the National Institute of Mental Health.
"The mapping of the path that the brain follows in deviating from normal development provides important clues to the underlying causes of the disorder," said Dr. John Krystal, Editor of Biological Psychiatry.
The findings were derived by investigating the trajectory of cortical thickness growth curves in 106 patients with childhood-onset schizophrenia and a comparison group of 102 healthy volunteers.
Each participant, ranging from 7–32 years of age, had repeated imaging scans over the course of several years. Then, using over 80,000 vertices across the cortex, the researchers modeled the effect of schizophrenia on the growth curve of cortical thickness.
This revealed differences that occur within a specific group of highly-connected brain regions that mature in synchrony during typical development, but follow altered trajectories of growth in schizophrenia.
"These findings show a relationship between the hypothesis that schizophrenia is a neurodevelopmental disorder and the longstanding hypothesis – first articulated by the German anatomist Karl Wernicke in the late 19th century – that it is a disease of altered connectivity between regions of the brain," added Alexander-Bloch.
This theoretical consistency is important, as it allows researchers to better focus future studies of brain connectivity in schizophrenia, by targeting the brain regions known to be affected.
Neural Anatomy of Primary Visual Cortex Limits Visual Working Memory
Despite the immense processing power of the human brain, working memory storage is severely limited, and the neuroanatomical basis of these limitations has remained elusive. Here, we show that the stable storage limits of visual working memory for over 9 s are bound by the precise gray matter volume of primary visual cortex (V1), defined by fMRI retinotopic mapping. Individuals with a bigger V1 tended to have greater visual working memory storage. This relationship was present independently for both surface size and thickness of V1 but absent in V2, V3 and for non-visual working memory measures. Additional whole-brain analyses confirmed the specificity of the relationship to V1. Our findings indicate that the size of primary visual cortex plays a critical role in limiting what we can hold in mind, acting like a gatekeeper in constraining the richness of working mental function.
(Image: Shutterstock)