Influences of Manipulating Scanpaths on Brain Activity Evoked by Faces

Background: Individuals with autism demonstrate abnormal visual scanpaths when looking at faces (Pelphrey et al., 2002, JADD; Klin et al., 2002, AGP). Additionally, these individuals show an absence of the usual face-selective activity in the fusiform gyrus (FFG) relative to typically developing individuals (Schultz et al., 2001, AGP). 

Objectives: Employing fMRI, our study explores the effects of manipulating time spent fixating upon the eyes on brain activity evoked by faces in people with and without autism. 

Methods: We created a paradigm in which a crosshair moves over an image of an actor displaying a fearful facial expression. Participants push a button when the crosshair changes color (this happens infrequently) to ensure that they maintain fixation on the crosshair. Four conditions were designed by modifying the typical scanpaths over the core features of the face: Low (32 % of the time spent on the eyes relative to other features), Medium (48%), High (56%), and Free Viewing (no crosshair). At this time, three people with high-functioning autism and 10 matched neurotypical individuals have participated in this ongoing study. 

Results: As predicted, typically developing individuals showed greater activation in the bilateral FFG (p < .005) to the High versus Low condition. Consistent with prior research, individuals with autism exhibited hypoactivation in the bilateral FFG. However, they showed greater activation in these areas in the High condition than in either the Low (p<.05) or Free Viewing (p<.05) conditions. 

Conclusions: These preliminary findings suggest that by encouraging individuals with autism to look at the eyes of faces and follow more typical scanpaths, we can normalize their FFG activation. This work could have implications for the ways in which we understand the potential mechanisms underlying interventions that encourage eye contact during social interactions.