Oxytocin and Self-Consciousness

In recent years, the study of self-consciousness from neuroscience and psychobiological perspectives has flourished rapidly. The understanding of the brain areas involved in self-consciousness and the complex intertwining of self-consciousness levels has expanded greatly, and the awareness of neurotransmitter influence on self-consciousness has begun to emerge. Despite this, the neuropeptidergic influences on self-consciousness have been largely ignored However, recent studies of the neuropeptide oxytocin have yielded promising results that further our understanding of the psychobiological foundations of self-consciousness. Here, we argue that the oxytocinergic system plays a role in modulating several levels of self-consciousness, a conclusion that is usually underscored in interpretations of previous studies. Several studies indicate, that the neuropeptide oxytocin plays a central role in social cognition (Heinrichs and Domes, 2008; Heinrichs et al., 2009). For example, oxytocin administration sharpens mind-reading skills (Domes et al., 2007), enhances understanding of other's perspective (Ditzen et al., 2009), and modulates evaluation of other's trustworthiness (Kosfeld et al., 2005). The cognition of self and other are closely interrelated and partly share the same brain network. For example, the medial prefrontal cortex is involved in other's mental state and personality inference tasks (Mitchell et al., 2002, 2004) as well as in evaluation of one's own personality traits (Johnson et al., 2002). Of note, oxytocin administration modulates the medial prefrontal cortex activity (Sripada et al., 2013). The understanding of others' perspectives and empathic responses also relies on the ability to recognize self-other differences. Oxytocin administration mediates the activation of brain areas, e.g., the posterior temporal sulcus (Pincus et al., 2010; Gordon et al., 2013), that are involved in mentalizing and processing self-other distinction (Decety and Lamm, 2007). Oxytocin is probably involved in both other-and self-related processing. Two fundamental issues regarding the oxytocinergic system and self-consciousness are of specific relevance. First, oxytocin is synthesized in the paraventricular and supraoptic nuclei of the hypothalamus and processed to the posterior pituitary lobe, through axonal projections, for release into peripheral circulation. In addition, dendrites release oxytocin into extracellular space, from where it diffuses to several distant areas in the brain. Oxytocin receptors have been found in several brain areas, including the periacqueductal gray, putamen, insula, amygdala, nucleus accumbens, and prefrontal cortex (Sofroniew, 1983; Tribollet et al., 1992; Meyer-Lindenberg et al., 2011). Of note, oxytocin diffuses from evolutionarily ancient areas primarily involved in arousal states and emotion expression to more recent distal brain areas involved in cognitively mediated processes. …