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Top1. Introduction
Consciousness is one of the central cognitive functions of the brain and the natural intelligence. Studies on consciousness can be traced back to as early as Aristotle’s era, when the dualism treats human beings as the body and soul or the brain and mind problems (Dennett, 1991; Kihlstrom, 1987; Leahey, 1997; Solso, 1999; Wilson & Keil, 2001). Consciousness is the basic characteristic of life and the mind, which is the state of being awareness of oneself, of perception to both internal and external worlds, and of responsive to one’s surroundings.
A variety of doctrines on consciousness are developed in psychology and cognitive science (Coaen et al., 1994; Leahey, 1997; Solso, 1999). John Locke (1632-1704) perceived that a major function of consciousness is to form a personal identity by linking past and present events to ourselves. James (1890) described consciousness as a constantly moving stream of thoughts, feelings, and perceptions. Kihlstrom (1987) identified that consciousness monitors the self and the environment, and controls thought and behavior (Kihlstrom, 1987). Dennett (1991) proposed that consciousness, our sense of self and intentionality, stems from the collective effect of low-level biological and physiological processes (Dennett, 1991). Lefton et al. (2005) perceived consciousness as the general state of being aware of and responsive to events within ourselves and in the environment (Lefton, 2005). Yingxu Wang and his colleagues developed the theory of the Layered Reference Model of the Brain (LRMB) (Wang et al., 2006), which reveals that consciousness is a collective state at the perception layer of the 7-layer LRMB model such as the sensation, action, memory, perception, metacognition, inference, and cognition layers from the bottom-up. The latest advances at Wang`s laboratory have pinpointed the Conscious Status Memory (CSM) in the cerebellum (Wang, 2012d).
Definition 1.Consciousness is a collective mental state of self awareness that represents the bodily and mental status and their relations to the external environment, which is inductively generated or synthesized from the levels of metabolic homeostasis, unconsciousness, subconsciousnes, and consciousness from bottom-up.
According to the LRMB model, consciousness is one of the cognitive processes of perception at Layer 4 (Wang et al., 2006) as illustrated in Figure 1. Consciousness is closely coupled with attentions, motivations, emotions, attitudes, imagination, sense of space, and sense of motion at the same layer. It is supported by lower layer functions such as those of the sensation, action, and memory layers. It also intensively interacts with other higher layer life functions and mental processes in the brain. Therefore, to a certain extent, consciousness may not be separately studied without considering the impact and interactions of other cognitive processes, particularly the attention and sensation processes, when the brain is perceived as an extremely intricate system.
Figure 1. Consciousness and its relationship to other LRMB processes in the brain