Consciousness in this sense has been compared to the blind spot in the retina where it is not an adaption of the retina, but instead just a by-product of the way the retinal axons were wired. Several scholars including Pinker, Chomsky, Edelman, and Luria have indicated the importance of the emergence of human language as an important regulative mechanism of learning and memory in the context of the development of higher-order consciousness (see Neural correlates section above). Another idea suggested where consciousness originates from a cell that has nestled itself in a blood capillary in the brain where the blood flow determines whether or not one is conscious. States of consciousness
There are some brain states in which consciousness seems to be absent, including dreamless sleep or coma. There are also a variety of circumstances that can change the relationship between the mind and the world in less drastic ways, producing what are known as altered states of consciousness. Some altered states occur naturally; others can be produced by drugs or brain damage. Altered states can be accompanied by changes in thinking, disturbances in the sense of time, feelings of loss of control, changes in emotional expression, alternations in body image and changes in meaning or significance.The two most widely accepted altered states are sleep and dreaming. Although dream sleep and non-dream sleep appear very similar to an outside observer, each is associated with a distinct pattern of brain activity, metabolic activity, and eye movement; each is also associated with a distinct pattern of experience and cognition.
Spiritual approaches
To most philosophers, the word "consciousness" connotes the relationship between the mind and the world. To writers on spiritual or religious topics, it frequently connotes the relationship between the mind and God, or the relationship between the mind and deeper truths that are thought to be more fundamental than the physical world. The mystical psychiatrist Richard Maurice Bucke, author of the 1901 book Cosmic Consciousness: A Study in the Evolution of the Human Mind,
distinguished between three types of consciousness:  Simple Consciousness, awareness of the body, possessed by many animals; Self Consciousness, awareness of being aware, possessed only by humans; and Cosmic Consciousness, awareness of the life and order of the universe, possessed only by humans who are enlightened. Many more examples could be given, such as the various levels of spiritual consciousness presented by Prem Saran Satsangi and Stuart Hameroff.Another thorough account of the spiritual approach is Ken Wilbers 1977 book The Spectrum of Consciousness, a comparison of western and eastern ways of thinking about the mind. Wilber described consciousness as a spectrum with ordinary awareness at one end, and more profound types of awareness at higher levels. See also
References
Further reading
External links

 The dictionary definition of consciousness at Wiktionary
 Consciousness Studies at Wikibooks
Gulick, Robert Van. "Consciousness". In Zalta, Edward N. (ed.). Stanford Encyclopedia of Philosophy. "Consciousness". Internet Encyclopedia of Philosophy.