Coherence in consciousness: paralimbic gamma synchrony of self-reference links conscious experiences.

A coherent and meaningful percept of the world is essential for human nature. Consequently, much speculation has focused on how this is achieved in the brain. It is thought that all conscious experiences have reference to the self. Self-reference may either be minimal or extended, i.e., autonoetic. In minimal self-reference subjective experiences are self-aware in the weak sense that there is something it feels like for the subject to experience something. In autonoetic consciousness, consciousness emerges, by definition, by retrieval of memories of personally experienced events (episodic memory). It has been shown with transcranial magnetic stimulation (TMS) that a medial paralimbic circuitry is critical for self-reference. This circuitry includes anterior cingulate/medial prefrontal and posterior cingulate/medial parietal cortices, connected directly and via thalamus. We here hypothesized that interaction in the circuitry may bind conscious experiences with widely different degrees of self-reference through synchrony of high frequency oscillations as a common neural event. This hypothesis was confirmed with magneto-encephalography (MEG). The observed coupling between the neural events in conscious experience may explain the sense of unity of consciousness and the severe symptoms associated with paralimbic dysfunction. (c) 2009 Wiley-Liss, Inc.