Altered resting perfusion and functional connectivity of default mode network in youth with autism spectrum disorder

Abstract

BackgroundNeuroimaging studies can shed light on the neurobiological underpinnings of autism spectrum disorders (ASD). Studies of the resting brain have shown both altered baseline metabolism from PET/SPECT and altered functional connectivity (FC) of intrinsic brain networks based on resting-state fMRI. To date, however, no study has investigated these two physiological parameters of resting brain function jointly, or explored the relationship between these measures and ASD symptom severity.MethodsHere, we used pseudo-continuous arterial spin labeling with 3D background-suppressed GRASE to assess resting cerebral blood flow (CBF) and FC in 17 youth with ASD and 22 matched typically developing (TD) children.ResultsA pattern of altered resting perfusion was found in ASD versus TD children including frontotemporal hyperperfusion and hypoperfusion in the dorsal anterior cingulate cortex. We found increased local FC in the anterior module of the default mode network (DMN) accompanied by decreased CBF in the same area. In our cohort, both alterations were associated with greater social impairments as assessed with the Social Responsiveness Scale (SRS-total T scores). While FC was correlated with CBF in TD children, this association between FC and baseline perfusion was disrupted in children with ASD. Furthermore, there was reduced long-range FC between anterior and posterior modules of the DMN in children with ASD.ConclusionTaken together, the findings of this study – the first to jointly assess resting CBF and FC in ASD – highlight new avenues for identifying novel imaging markers of ASD symptomatology.

Cerebral hypoperfusion in autism spectrum disorder

“…Cerebral hypoperfusion has been demonstrated in ASD as compared to healthy controls in many parts of the brain, typically using positron emission tomography (PET) or single-photon emission computed tomography (SPECT) (Boddaert and Zilbovicius 2002, Galuska et al 2002, Sasaki 2015, Zilbovicius et al 1995, 2000. Further scanning methods such as fMRI were also adopted in ASD neuro-imaging with encouraging results (Dichter 2012, Jann et al 2015, Philip et al 2012. The hypoperfusion was detected on an individual basis in nearly 75% of the ASD children, with the current sensitivity of the imaging method (Zilbovicius et al 2000).…”

Dual‐echo ASL contributes to decrypting the link between functional connectivity and cerebral blow flow

“…The DE‐ASL acquisition had the same TE and the same number of time‐points of the cvBOLD acquisition for the ccBOLD part, but a lower temporal resolution. Nonetheless, it has been noted that the temporal resolution has only minor effects on FC estimation, while the total scan length is a critical factor affecting FC reliability (Birn et al, ; Jann et al, ; Smith et al, ). In particular, it has been suggested that longer duration acquisitions can maximize similarity of overall whole‐brain connectivity, with clear stability benefits for 10 min rather than 5 min scans (Gonzalez‐Castillo et al, ; Birn et al, ), and can yield more power for detecting smaller correlations while providing more precise estimates of the size of correlations [van Dijk et al, ].…”

“…However, a short PLD would result in less T1 decay and thus higher SNR which is clearly advantageous for connectivity studies. Noteworthy, short PLDs with pCASL sequences (1,000–1,200 ms) have already been adopted by some researchers for concomitant connectivity analyses and CBF quantification [Cohen at al., 2016; Jann et al, ; Liang et al, ; Tak et al, ].…”

Functional Neural Network Connectivity in Myalgic Encephalomyelitis

“…Cognitive symptoms produced by a failure within this network would involve decreased attention, mentalizing, decisionmaking, self-referential thought, and self-recognition. The default-mode network has been implicated in symptoms of a variety of neurocognitive disorders such as Alzheimer's disease (Greicius, Srivastava, Reiss, & Menon, 2004), Parkinson's disease (van Eimeren, Monchi, Ballanger, & Strafella, 2009), traumatic brain injury (Bonnelle et al, 2011), multiple sclerosis (Zhou et al, 2014), epilepsy (Haneef, Lenartowicz, Yeh, Engel, & Stern, 2014), autism (Jann et al, 2015). In ME, the relative interactions between nodes of the default-mode network could be examined using phase and coherence metrics within LORETA to explore temporal dynamics within a graph theoretical framework; the connectivity of edges between dysfunctional nodes identified as hyper/hypo connected according to EEG frequency band .…”