Inter-regional brain communication and its disturbance in autism
http://www.frontiersin.org/systems_neuroscience/10.3389/fnsys.2011.00010/full
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.
Thus, brain volume measurements have revealed that the rate of brain growth in autism slows after age 4, leading to a decreased volume of white matter in adolescents with autism relative to neurotypical adolescents. Given that white matter is the medium which is used for inter-regional brain communication, it seems incontrovertible that brain connectivity is disrupted in autism.
Altered functional connectivity has also been found in other disorders, including schizophrenia (Meyer-Lindenberg et al., 2001), attention deficit hyperactivity disorder (Tian et al., 2006), multiple sclerosis (Au Duong et al., 2005), and dyslexia (Pugh et al., 2000). These findings suggest that disordered brain connectivity may underlie a variety of cognitive impairments.
While autism is primarily associated with frontal–posterior underconnectivity, preliminary evidence suggests that these other disorders are linked with impairments in other types of connections (Pugh et al., 2000; Meyer-Lindenberg et al., 2001; Au Duong et al., 2005; Tian et al., 2006).
Recent findings of atypical patterns in both functional and anatomical connectivity in autism have established that autism is a not a localized neurological disorder, but one that affects many parts of the brain in many types of thinking tasks. fMRI studies repeatedly find evidence of decreased coordination between frontal and posterior brain regions in autism, as measured by functional connectivity.
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