Oromucosal Oxytocin and Vasopressin Modulation of Emotional Face Attention

Oxytocin (OT) and arginine vasopressin (AVP) are neuropeptides involved in social and emotional processing. Previous studies have shown that intranasal OT can modulate top-down and bottom-up attention to emotional faces. Other work has also suggested that OT and AVP may exert both overlapping and distinct effects on social attention. In addition, emerging evidence indicates that oromucosal and intranasal OT administration may produce similar behavioral effects but different neural response patterns. The present study therefore extends previous work by examining the behavioral and neural effects of oromucosally administered OT and AVP within the same emotional attention paradigm.

In a randomized, placebo-controlled, double-blind, between-subject design, healthy adults will receive 24 IU OT, 24 IU AVP, or placebo (PLC) via a lyophilized oromucosal lollipop. Participants will allow the treatment to be absorbed through the oral mucosa for approximately 5 minutes, followed by a 30-minute resting period and post-treatment blood sampling before fMRI scanning.

To control for potential confounding effects and individual differences, participants will complete the Autism Spectrum Quotient, State-Trait Anxiety Inventory, Beck Depression Inventory, and Toronto Alexithymia Scale before treatment administration. Current affective state will be assessed using the Positive and Negative Affect Schedule (PANAS) at three time points: upon arrival at the laboratory, at the beginning of the scanning task, and after completion of the scan.

During fMRI, participants will complete emotional face attention tasks assessing top-down and bottom-up processing under high and low attentional load. Response time, response accuracy, task-evoked BOLD signals, and peripheral neuropeptide levels will be measured to characterize similarities and differences in the effects of OT and AVP on emotional attention.

Inclusion criteria

• Healthy subjects without past or current psychiatric or neurological disorders
• Normal or corrected-to-normal vision
• Eligible for MRI scanning and willing to undergo blood sampling and study treatment administration
• For naturally cycling female participants, willingness and ability to complete the experimental session within the predefined menstrual-cycle phase, determined using menstrual history and urinary luteinizing hormone (LH) testing
• Willing to comply with study requirements regarding alcohol, caffeine, nicotine, medication use, and other pre-session restrictions

Exclusion criteria

• History of head injury or epilepsy or seizure disorders
• Current or past major psychiatric, neurological, or serious medical illness that may affect participant safety or study outcomes
• Current use of psychoactive medications, hormonal medications, or other medications that may substantially affect central nervous system or neuroendocrine function
• Regular smoking or inability to comply with the required nicotine abstinence period before testing
• Face recognition impairment or other visual-perceptual impairment that could interfere with performance of the emotional face tasks