Consciousness was first described and introduced by Sigmund Freud and Friedrich Nietzsche (Crick & Koch, 2001). It has been described as an area of ​​the mind that controls human behavior. However, consciousness is not accessible to conscious introspection, self-examination, or a source of knowledge. On the contrary, Christof Koch, neuroscientist collaborator of Francis Crick, describes unconsciousness as any neuronal activity that does not give rise to conscious sensations, thoughts or memories (Crick & Koch, 2001). Although unconsciousness differs from consciousness in many ways, it functions in a waking state that deals with cause and effect as well as spontaneous logical processes in order to process information. Rather, the unconscious mind is associated with involuntary activities that make connections with thoughts, ideas, and reflections, and this unconscious mind also has the ability to multitask. Therefore, as Koch explains, the unconscious puts humans into an “online” mode, allowing us to bypass our instinctive “offline” programming. Scientists and philosophers have different understandings and explanations of consciousness as it was once observed from a philosophical perspective. only. However, thanks to technological advances in understanding the brain from a computational, biomolecular, cognitive and behavioral approach, consciousness is also studied from a neuroscientific approach. Therefore, neuroscientists have difficulty verifying and understanding its existence. For example, Dennet believes that consciousness is the evolved capacity for self-knowledge that gives us subjective experience. While Francis Crick considers from a completely neuroscientific perspective that one must examine the neural correlates...... middle of article...... Natural Correlates of Consciousness (Cambridge, Mass: MIT Press, 2000) NCC. Retrieved December 29, 2011Reagan, Leslie A. et al, eds. (2007). Animated images from Pavlov Children Medicine. Rochester, New York: University of Rochester Press. p. 285. Retrieved December 7, 2011. Scheff, Thomas Ph.D. 2009. Emotional/relational world. Psychology today. www.psychologytoday.com. Accessed December 2, 2011. http://www.psychologytoday.com/blog/lets-connect/200909/the- emotionalrelational-world Shear, J., Explaining Consciousness – The Hard Problem (Cambridge, Mass: MIT Press, 1997) ( and Journal of Consciousness Studies 1995)Tsuchiya & Koch. (2009) Tsuchiya, Naotsugu. Koch, Christof. The relationship between consciousness and attention. Chapter 6. The Journal of the Neurology of Consciousness. www.klab.caltech.edu. Retrieved December 2 2011.