Aberrant functional connectivity in autism: Evidence from low-frequency BOLD signal fluctuations

Abstract

A number of recent studies have examined functional connectivity in individuals with Autism Spectrum Disorders (ASD), generally converging on the finding of reduced interregional coordination, or underconnectivity. Underconnectivity has been reported between many brain regions and across a range of cognitive tasks, and has been proposed to underlie behavioral and cognitive impairments associated with ASD. The current study employed functional connectivity MRI (fcMRI) to examine interregional correlations of low-frequency BOLD signal fluctuations in 10 high-functioning participants with ASD and 10 typically developing control participants. Wholebrain connectivity with three seed regions of interest (left middle frontal, left superior parietal, and left middle occipital cortex) was evaluated using fMRI datasets acquired during performance of a source recognition task. While fcMRI patterns were found to be largely similar across the two groups, including many common areas, effects for the ASD group were generally more extensive. These findings, although inconsistent with generalized underconnectivity in ASD, are compatible with a model of aberrant connectivity in which the nature of connectivity disturbance (i.e., increased or reduced) may vary by region. Taking into consideration methodological factors that might influence measured fcMRI effects, we suggest that ASD is associated with an inefficiency in optimizing network connections to achieve task performance.

Developing Synaesthesia

“…Increased activation in associative cortex regions involved in higher order sensory processing has been found in ASC individuals in the visual domain (Samson et al, 2012), while increased functional connectivity between frontal areas (Noonan et al, 2009) and between posterior cingulate and medial temporal cortex (Monk et al, 2009) has been found using fMRI. In synesthesia, the parietal cortex especially has been found to be hyperactivated in different types of synesthesia and this region has also been found to be more strongly connected to the sensory areas involved in inducer-and concurrent processing , supporting the idea of top-down modulation of sensory areas by this higher-order associative region.…”

“…Every patient was examined for axis-I co-morbidity by using the German version of the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) (Wittchen et al, 1997).…”

Neurotechnology and Psychiatric Biomarkers

“…Complex networks are characterized by dense local connectivity and sparser long-range connectivity (Barabasi, 2009) that is fractal or selfsimilar at all scales. Many brain disorders appear to be associated with abnormal brain connectivity that may vary between different regions and different scales (Bassett and Bullmore, 2009;Craddock et al, 2009;Noonan et al, 2009). Examples include autism (Belmonte et al, 2004;Noonan et al, 2009), schizophrenia (Raghavendra et al, 2009;Uhlhaas et al, 2008;Whittington, 2008), depression (Li et al, 2008;Sheline et al, 2009) and epilepsy (Douw et al, 2010;Percha et al, 2005).…”

“…Complex mental disorders such as autism are associated with abnormal brain connectivity that may vary between different regions and different scales (Noonan et al, 2009). Estimation of changes in neural connectivity might be an effective diagnostic biomarker for abnormal connectivity development that leads to ASD behaviors.…”

Functional and Structural MR Imaging in Neuropsychiatric Disorders, Part 2: Application in Schizophrenia and Autism

“…Task-dependent fMRI studies showed alterations in memory, 45 recognition of face expression, 46 selective attention, 47 cognitive control and executive function, 48 self-and other reflection, 49 self-representation, 50 and motor-response inhibition 51 in patients with ASD. Final conclusions were not yet derived from these studies because of the heterogeneity of paradigms as well as the diagnostic entities and age groups included.…”