Oxytocin Increases Processing Efficiency of Socially Salient Visual Information

Background:   The social motivation hypothesis suggests that social dysfunction in ASD, such as deficits in face processing, derive from atypical processing of socially rewarding stimuli. The neuropeptide oxytocin plays a key role in social behavior and is hypothesized to modulate the dopaminergic reward pathway during social interaction. Functional neuroimaging in healthy adults suggests that intranasally administered oxytocin enhances activity in brain regions involved in face processing; however, the modulatory influences of individual differences and context are poorly understood. Likewise, scant research has applied temporally sensitive imaging methods to examine the impact of oxytocin on face perception with regard to time course and stages of processing.  For example, it is not understood whether oxytocin preferentially affects allocation of attention to relevant facial features or emotion decoding.

Objectives:   The current study used event-related potentials (ERPs) to investigate the temporal dynamics of oxytocin’s influence on the neural substrates of face perception. In addition, the relationships between autistic and anxious traits on the impact of oxytocin during face perception were evaluated. We predicted that oxytocin would significantly reduce latency of ERP components associated with face perception and that these reductions would be modulated by stimuli characteristics and individual traits.

Methods:   Twenty-one typically developing adults completed two EEG recordings on two separate days in a double-blind, placebo-controlled within-subject design. Trait anxiety and autistic traits were measured using the State-Trait Anxiety Inventory (STAI) and the Social Responsiveness Scale (Adult Self-Report, SRS-A-SR). ERPs were recorded during administration of two experimental paradigms. In Experiment 1, neutral face and fearful face stimuli were presented in random sequence. In Experiment 2, grayscale digital images of neutral faces were presented while point of gaze was manipulated by preceding fixation points directing attention to the eyes, nose, or mouth. An ERP index of face perception (N170) was extracted for neutral and fearful faces in Experiment 1 and for each facial region in Experiment 2. In addition, an index of oxytocin sensitivity was calculated by computing N170 latency difference scores between conditions and oxytocin and placebo visits.

Results:   In Experiment 1, N170 latency was significantly shorter to fearful faces only for subjects who had inhaled oxytocin (p=0.039). In Experiment 2, a main effect of condition indicated shorter N170 latency to the eye region compared the mouth and middle face regions (p=0.002). In the right hemisphere, N170 latency was significantly shorter to the eyes for subjects who had inhaled oxytocin (p=0.028). Self-reported anxiety (p=0.012) and lower self-reported social responsiveness (p=0.036) were significantly associated with sensitivity to oxytocin (i.e., individuals with higher anxiety displayed shorter N170 latency and individuals with lower SRS showed shorter N170 latency).

Conclusions: Intranasal administration of oxytocin resulted in increased processing efficiency of socially relevant information in terms of both facial affect and eye gaze. These effects were most pronounced in individuals with higher levels of autistic and anxious traits.  Results emphasize the importance of applying temporally sensitive imaging methods to examine treatment-associated changes in processing efficiency and add to evidence supporting the potential utility of oxytocin to ameliorate autistic symptomatology.