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Inter-regional brain communication and its disturbance in autism.

Schipul SE, Keller TA, Just MA - Front Syst Neurosci (2011)

Bottom Line: Specifically, the underconnectivity theory of autism postulates that individuals with autism have a reduced communication bandwidth between frontal and posterior cortical areas, which constrains the psychological processes that rely on the integrated functioning of frontal and posterior brain networks.It also summarizes the findings of disordered anatomical connectivity in autism, as measured by a variety of techniques, including distribution of white matter volumes and diffusion tensor imaging.We conclude with a discussion of the implications of these findings for autism and future directions for this line of research.

View Article: PubMed Central - PubMed

Affiliation: Center for Cognitive Brain Imaging, Department of Psychology, Carnegie Mellon University Pittsburgh, PA, USA.

ABSTRACT
In this review article, we summarize recent progress toward understanding disturbances in functional and anatomical brain connectivity in autism. Autism is a neurodevelopmental disorder affecting language, social interaction, and repetitive behaviors. Recent studies have suggested that limitations of frontal-posterior brain connectivity in autism underlie the varied set of deficits associated with this disorder. Specifically, the underconnectivity theory of autism postulates that individuals with autism have a reduced communication bandwidth between frontal and posterior cortical areas, which constrains the psychological processes that rely on the integrated functioning of frontal and posterior brain networks. This review summarizes the recent findings of reduced frontal-posterior functional connectivity (synchronization) in autism in a wide variety of high-level tasks, focusing on data from functional magnetic resonance imaging studies. It also summarizes the findings of disordered anatomical connectivity in autism, as measured by a variety of techniques, including distribution of white matter volumes and diffusion tensor imaging. We conclude with a discussion of the implications of these findings for autism and future directions for this line of research.

No MeSH data available.


Related in: MedlinePlus

Correlations between functional and anatomical connectivity. Functional connectivity is correlated with corpus callosum size in autism participants (A) but not control participants (B). Adapted from Just et al. (2007).
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Figure 2: Correlations between functional and anatomical connectivity. Functional connectivity is correlated with corpus callosum size in autism participants (A) but not control participants (B). Adapted from Just et al. (2007).

Mentions: Several studies have reported correlations between functional connectivity and corpus callosum area measurements in autism. The corpus callosum is a major white matter tract connecting the two hemispheres, and many studies have reported smaller corpus callosum sizes in ASD (Vidal et al., 2006; Hardan et al., 2009; Keary et al., 2009). Although this effect has not always been found at lower magnetic field strengths (0.5–1.5 T: Gaffney et al., 1987; Rice et al., 2005; Tepest et al., 2010), two meta-analyses found that smaller corpus callosum size in ASD is significant across MRI studies (Stanfield et al., 2008; Frazier and Hardan, 2009). Furthermore, magnetic field strength was shown to be a marginally significant predictor of group differences, such that stronger magnets show larger discrepancies in corpus callosum size between ASD and neurotypical participants (Frazier and Hardan, 2009). Because the corpus callosum is such a critical pathway in the brain and is often found to be smaller in autism, corpus callosum size is sometimes used as an index of general anatomical connectivity in the brain. Several studies have found measures of functional connectivity to be positively correlated with corpus callosum size in autism (Cherkassky et al., 2006; Kana et al., 2006; Just et al., 2007; Mason et al., 2008), as illustrated in Figure 2. Furthermore, in all of the above studies, this correlation was not found in the control group, suggesting that only in autism is communication between distinct brain areas constrained by impaired anatomical connectivity.


Inter-regional brain communication and its disturbance in autism.

Schipul SE, Keller TA, Just MA - Front Syst Neurosci (2011)

Correlations between functional and anatomical connectivity. Functional connectivity is correlated with corpus callosum size in autism participants (A) but not control participants (B). Adapted from Just et al. (2007).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3046360&req=5

Figure 2: Correlations between functional and anatomical connectivity. Functional connectivity is correlated with corpus callosum size in autism participants (A) but not control participants (B). Adapted from Just et al. (2007).
Mentions: Several studies have reported correlations between functional connectivity and corpus callosum area measurements in autism. The corpus callosum is a major white matter tract connecting the two hemispheres, and many studies have reported smaller corpus callosum sizes in ASD (Vidal et al., 2006; Hardan et al., 2009; Keary et al., 2009). Although this effect has not always been found at lower magnetic field strengths (0.5–1.5 T: Gaffney et al., 1987; Rice et al., 2005; Tepest et al., 2010), two meta-analyses found that smaller corpus callosum size in ASD is significant across MRI studies (Stanfield et al., 2008; Frazier and Hardan, 2009). Furthermore, magnetic field strength was shown to be a marginally significant predictor of group differences, such that stronger magnets show larger discrepancies in corpus callosum size between ASD and neurotypical participants (Frazier and Hardan, 2009). Because the corpus callosum is such a critical pathway in the brain and is often found to be smaller in autism, corpus callosum size is sometimes used as an index of general anatomical connectivity in the brain. Several studies have found measures of functional connectivity to be positively correlated with corpus callosum size in autism (Cherkassky et al., 2006; Kana et al., 2006; Just et al., 2007; Mason et al., 2008), as illustrated in Figure 2. Furthermore, in all of the above studies, this correlation was not found in the control group, suggesting that only in autism is communication between distinct brain areas constrained by impaired anatomical connectivity.

Bottom Line: Specifically, the underconnectivity theory of autism postulates that individuals with autism have a reduced communication bandwidth between frontal and posterior cortical areas, which constrains the psychological processes that rely on the integrated functioning of frontal and posterior brain networks.It also summarizes the findings of disordered anatomical connectivity in autism, as measured by a variety of techniques, including distribution of white matter volumes and diffusion tensor imaging.We conclude with a discussion of the implications of these findings for autism and future directions for this line of research.

View Article: PubMed Central - PubMed

Affiliation: Center for Cognitive Brain Imaging, Department of Psychology, Carnegie Mellon University Pittsburgh, PA, USA.

ABSTRACT
In this review article, we summarize recent progress toward understanding disturbances in functional and anatomical brain connectivity in autism. Autism is a neurodevelopmental disorder affecting language, social interaction, and repetitive behaviors. Recent studies have suggested that limitations of frontal-posterior brain connectivity in autism underlie the varied set of deficits associated with this disorder. Specifically, the underconnectivity theory of autism postulates that individuals with autism have a reduced communication bandwidth between frontal and posterior cortical areas, which constrains the psychological processes that rely on the integrated functioning of frontal and posterior brain networks. This review summarizes the recent findings of reduced frontal-posterior functional connectivity (synchronization) in autism in a wide variety of high-level tasks, focusing on data from functional magnetic resonance imaging studies. It also summarizes the findings of disordered anatomical connectivity in autism, as measured by a variety of techniques, including distribution of white matter volumes and diffusion tensor imaging. We conclude with a discussion of the implications of these findings for autism and future directions for this line of research.

No MeSH data available.


Related in: MedlinePlus