Brain Function and Connectivity during Attention Orienting in Autism Spectrum Disorder

Background: Spatial orienting of attention is a cognitive function that allows a person to move their attentional focus from one location to another location in response to a stimulus. Attention orienting can be triggered in two ways; exogenously and endogenously. Exogenous attention orienting refers to the shift in attentional focus that occurs in an automatic, reflexive manner in response to sudden onset stimuli. Endogenous attention orienting describes voluntary, goal-driven shifting of attention; for example in response to a cue that signals where to look or listen.
Orienting attention to new and important sources of information is crucial for learning and normal socio-emotional development. The majority of the attention cuing literature suggests that exogenous, stimulus-driven attention orienting is impaired in Autism Spectrum Disorder (ASD). Surprisingly, only a handful of studies have examined endogenous orienting in ASD and the findings are inconsistent. Difficulties in attention orienting may contribute to the development of a number of core features of ASD. It has been suggested that abnormal joint attention, unusual eye contact, lack of response to auditory or visual stimuli and slowed shifting of attention could all result from an underlying deficit in attention orienting. Dysfunctional attention orienting may be an important factor contributing to social communication difficulties in autism.
Attention orienting appears to be subserved by two interacting networks. A bilateral dorsal frontoparietal network is involved in endogenous goal-directed attention orienting, whereas a largely right lateralised ventral frontoparietal system is activated during stimulus-driven attentional orienting. It is thought that this ventral network functions as a circuit breaker for the dorsal network and directs attention to behaviourally relevant stimuli outside the focus of processing.
Recent neuroimaging research has revealed abnormal interregional functional connectivity in ASD during a variety of cognitive tasks.  This study aims to investigate whether there is abnormal functional connectivity between frontal and parietal regions in the ASD group during this task.
Objectives: To compare brain activation and functional connectivity during exogenous and endogenous attention orienting in individuals with ASD and controls.

Methods: Participants with ASD and age and IQ matched controls will perform a Posner style attention orienting task during functional MRI in a 3T scanner. Presentation of a central arrow cue activates endogenous goal-directed attention orienting. When the target is invalidly cued, i.e. appears at an unexpected location, exogenous, stimulus driven attention orienting is activated. Regions of brain activation are compared between cases and controls using AFNI software. Functional connectivity analysis will be performed.

Results: Preliminary results are in keeping with the research that suggests that two frontoparietal networks are involved in goal directed and stimulus-driven attention orienting. Recruitment and testing is ongoing.
Conclusions: Based on prior evidence from the literature, we expect to see significant brain activation differences between cases and controls during fMRI. Based on a number of recent studies of functional connectivity in ASD, we expect to find abnormal interregional connectivity in the ASD group. These findings will be important for our understanding of brain function in ASD.