Partially enhanced thalamocortical functional connectivity in autism

Mizuno, Akiko; Villalobos, Michele; Davies, Molly; Dahl, Branelle C.; Müller, Ralph Axel

doi:10.1016/j.brainres.2006.05.064

Cited by 187 publications

(147 citation statements)

References 93 publications

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“…Moreover, there are indications that the thalamus is smaller in men with high-functioning autism than in normal control men (Tsatsanis et al, 2003). Surprisingly, a recent study indicated more extensive thalamo-cortical functional connectivity in high functioning men with autism, compared to controls, which is in contrast to the hypothesis of general underconnectivity in ASD (Mizuno, Villalobos, Davies, Dahl, & Muller, 2006). The apparently normal performance of subjects with ASD in the present study does not support the idea that abnormalities in thalamic functioning play an important role in the potential problems with auditory-visual integration shown by high-functioning individuals with ASD, although different pathways might be involved.…”

Section: Discussionmentioning

confidence: 89%

Brief Report: Can You See What is Not There? Low-level Auditory–visual Integration in Autism Spectrum Disorder

Smagt

Engeland

Kemner

2007

J Autism Dev Disord

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Patients diagnosed with Autism Spectrum Disorder, show impaired integration of information across different senses. The processing-level from which this impairment originates, however, remains unclear. We investigated low-level integration of auditory and visual stimuli in subjects with Autism Spectrum Disorder. High-functioning adult subjects with Autism Spectrum Disorder as well as age-and IQ-matched adults were tested using a task that evokes illusory visual stimuli, by presenting sounds concurrently with visual flashes. In both groups the number of sounds presented significantly affected the number of flashes perceived, yet there was no difference between groups. This finding implicates that any problems arising from integrating auditory and visual information must stem from higher processing stages in high-functioning adults with Autism Spectrum Disorder.

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Section: Discussionmentioning

confidence: 89%

Brief Report: Can You See What is Not There? Low-level Auditory–visual Integration in Autism Spectrum Disorder

Smagt

Engeland

Kemner

2007

J Autism Dev Disord

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“…Participants performed the simple visuomotor tasks described previously. One study examined functional connectivity of the thalamus (Mizuno et al 2006). Our expectation of reduced thalamocortical fcMRI effects -based on some previous findings implicating the thalamus (Tsatsanis et al 2003) and thalamo-cortical connections (Chugani et al 1997) -was not confirmed.…”

Section: Investigating Autism As a Distributed Disordermentioning

confidence: 85%

The study of autism as a distributed disorder

Müller

2007

Ment. Retard. Dev. Disabil. Res. Rev.

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175

135

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Past autism research has often been dedicated to tracing the causes of the disorder to a localized neurological abnormality, a single functional network, or a single cognitive-behavioral domain. In this review, I argue that autism is a 'distributed disorder' on various levels of study (genetic, neuroanatomical, neurofunctional, behavioral). 'Localizing' models are therefore not promising. The large array of potential genetic risk factors suggests that multiple (or all) emerging functional brain networks are affected during early development. This is supported by widespread growth abnormalities throughout the brain. Interactions during development between affected functional networks and atypical experiential effects (associated with atypical behavior) in children with autism further complicate the neurological bases of the disorder, resulting in an 'exponentially distributed' profile. Promising approaches to a better characterization of neural endophenotypes in autism are provided by techniques investigating white matter and connectivity, such as MR spectroscopy, diffusion tensor imaging (DTI), and functional connectivity MRI. According to a recent hypothesis, the autistic brain is generally characterized by 'underconnectivity'. However, not all findings are consistent with this view. The concepts and methodology of functional connectivity need to be refined and results need to be corroborated by anatomical studies (such as DTI tractography) before definitive conclusions can be drawn.

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“…Several studies report developmental abnormalities in white matter tracts in autism spectrum disorder individuals (40)(41)(42), suggesting that deficits in normal axon guidance and connectivity might contribute to the pathophysiology of autism. The recent association of a de novo nonsense mutation in the EPHB2 kinase domain to autism (43) suggests that a deficit in EphB forward signaling increases risk for autism.…”

Section: Discussionmentioning

confidence: 99%

EphB receptor forward signaling regulates area-specific reciprocal thalamic and cortical axon pathfinding

Robichaux

Chenaux

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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In early brain development, ascending thalamocortical axons (TCAs) navigate through the ventral telencephalon (VTel) to reach their target regions in the young cerebral cortex. Descending, deep-layer cortical axons subsequently target appropriate thalamic and subcortical target regions. However, precisely how and when corticothalamic axons (CTAs) identify their appropriate, reciprocal thalamic targets remains unclear. We show here that EphB1 and EphB2 receptors control proper navigation of a subset of TCA and CTA projections through the VTel. We show in vivo that EphB receptor forward signaling and the ephrinB1 ligand are required during the early navigation of L1-CAM + thalamic fibers in the VTel, and that the misguided thalamic fibers in EphB1/2 KO mice appear to interact with cortical subregion-specific axon populations during reciprocal cortical axon guidance. As such, our findings suggest that descending cortical axons identify specific TCA subpopulations in the dorsal VTel to coordinate reciprocal corticalthalamic connectivity in the early developing brain.

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Partially enhanced thalamocortical functional connectivity in autism

Cited by 187 publications

References 93 publications

Brief Report: Can You See What is Not There? Low-level Auditory–visual Integration in Autism Spectrum Disorder

Brief Report: Can You See What is Not There? Low-level Auditory–visual Integration in Autism Spectrum Disorder

The study of autism as a distributed disorder

EphB receptor forward signaling regulates area-specific reciprocal thalamic and cortical axon pathfinding

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