The modularity of consciousness: a neurobehavioural perspective

Consciousness seems to be an elusive subject for scientific research, given the vast range of meanings that can be attached to this concept. However, from an operational point of view, consciousness can be identified with its two dimensions of level and contents. The level of consciousness or arousal is related to the state of wakefulness or vigilance, whereas the contents of consciousness are related to the awareness of phenomenal experience. Together these conscious processes generate a global system that is able to elaborate information coming from inside and outside the body. The sense of unity which derives from conscious experience seems to be deep and real, however some neurological syndromes give support to the hypothesis that the unity of consciousness might be apparent. We argue that it is when certain brain structures are selectively impaired that consciousness reveals its composite nature. From this perspective, we shall examine some empirical data from the study of epilepsy and split-brain syndrome, which can demonstrate how consciousness may be based on a modular organization, especially with regards to its phenomenal contents. Our phenomenal awareness could therefore emerge from different neural processes, which are vastly distributed across the brain rather than being the product of a specific cerebral circuitry.