This study investigates the efficacy of a single-dose of exogenous oxytocin administration on socially adaptive mirror-motor mapping in participants with Autism Spectrum Disorders. A placebo-controlled cross-over trial will be conducted: each participant will receive both a single-dose of placebo and oxytocin in two sessions separated by one week. The order of nasal spray will be randomised across participants. Mirror-motor mapping will be assessed by transcranial magnetic stimulation (TMS), a standard technique to investigate mirror system activity.

The brain's action observation network or 'mirror system' supports a variety of socio-cognitive functions, as it enables us to internally simulate and understand others' actions, emotions and intentions. Generally, mirror responses are larger upon the observation of actions accompanied by relevant information for the observer, such as direct eye contact from the actor. In other words, 'mirroring' is adaptively modulated according to the social salience of the observed actions (i.e. it is socially adaptive).

Individuals with Autism Spectrum Disorders (ASD) are known to endure difficulties with correctly recognizing eye contact as a communicative cue. Instead, they tend to experience eye contact as stressful and arousing. It is therefore hypothesized that, upon the observation of actions combined with salient gaze cues from the actor, these mirroring processes will not be adaptively modulated in participants with ASD.

As appropriate processing of eye contact is a key aspect of (non-verbal) communicative behavior, the investigator will investigate the efficacy of a single dose of intranasal oxytocin administration for enhancing socially-adaptive mirroring in ASD. Oxytocin is a neuropeptide that acts as a regulator social brain areas. On a behavioral level, it is known to enhance the saliency of observed social cues and to improve prosocial behavior. As such, it is regarded a promising intervention for alleviating the social and communicative deficits in ASD.

Inclusion Criteria:

• Male
• Young adults (between 18 - 35 y/o)
• Right-handed
• Official diagnosis of Autism Spectrum Disorders (for ASD participants)

Exclusion Criteria:

• Female
• Left-handed
• Any neuro(psycho)logical / psychiatric illness (for healthy controls)
• Motor dysfunctions of the hands / arms
• Any contradiction to TMS research as assessed with the TMS screening list: no metal objects in the body (e.g. pacemaker, coronary bypass clips, implants, medication pumps, ...), history of brain trauma in the past (e.g. meningitis, epilepsy, surgery, ...) or history of drug and/or alcohol abuse.