The word ‘conciousness’ is derived from Latin, having its roots in conscio formed by the coalescence of cum meaning ‘with’ and scio meaning ‘know’ (Sousa, 2013). Consciousness has been one of the most important and tantalizing issues ever since the origin of philosophy and medicine (Facco et al., 2017). The understanding of consciousness has been one of the most complex intellectual, philosophical and cognitive challenges faced by a spectrum of disciplines, ranging from quantum physics and psychology to neurosciences (Jasper et al., 1999; Sousa, 2013).
In general terms consciousness is defined as the state of awareness of self and the environment. In biological terms, human consciousness appears as a feature associated with the functioning of the human brain (Gierer, 2008). Consciousness can be defined as the subjective awareness of the momentary experience interpreted in the context of personal memory and present state (John, 2003). The English philosopher John Locke stated that consciousness is the awareness of all that occurs in the mind of a person. According to Meares (1999) self is a manifestation of this highest level of consciousness.
Consciousness is the experience or the content of experience from moment to moment. According to Boly (2011) to be conscious, is to be alert, active and vigilant. Consciousness has two major components: Awareness (i.e., the content of consciousness) and arousal (i.e. the level of consciousness) (Laureys, 2005). Synchronized activity of 10 million neurons over merely 230 ms produce conscious states (Hebb, 1949). Libet (1993) states that consciousness is associated with neuronal activities that persist for a long enough time with a minimal duration of 500 ms.
As described by van Gulick (2004) consciousness is the state or quality of awareness, or, of being aware of an external object or something within oneself. In modern science it is defined as a continuous state of full awareness of the Self and one's relationship to the external and internal environment, describing the degree of wakefulness in which an organism recognizes stimuli (Jellinger, 2009).
Consciousness arises as a result of integration of many inputs by reentrant interactions in the dynamic core (Edelman, 2003). Consciousness is a rich biological phenomenon and consciousness is based on the premise that phenomenal experience is entailed by neuronal activity in the brain (Seth et al., 2006). The thalamus governs levels of the conscious state and the content of consciousness depends on the activity of various cortical areas (Edelman, 2003). Direct injuries to the central thalamus can alone produce global disturbances of consciousness (Parvizi and Damasio, 2008).
According to the apical dendrite activity theory the pical dendrite part of thalamocortical circuits is the generator of consciousness (LaBerge, 2006). According to the biological theories consciousness is some form of biological state of the brain depends on brain chemistry and electrical impulses. Current research suggests that human consciousness is associated with complex, synchronous interactions between multiple cortical networks (Panda et al, 2016). According to Szirmai and Kamondi (2006) higher functions" of human mental ability have been ascribed to the prefrontal and parietal association cortices. The paleocerebrum, limbic system and their connections have been considered to be the center of emotions, feelings, attention, motivation and autonomic functions.
Consciousness is a primary function and activity of the human brain itself (Mahowald, 1997). Conscious perception arises from dialogue between prefrontal cortex, as the seat of the self, and sensory cortex (Baars et al, 2003). Consciousness is strongly connected with awareness. Neuroimaging studies suggest that frontoparietal activity makes an important contribution to conscious perception (Sousa, 2013). However there is no conscious perception without attention (Mack & Rock, 1998). There are four states of consciousness such as Waking: Sleeping: Dreaming: Meditation.
The American Psychologist William James postulated that our conscious mental life flows continuously like a stream in which “the transition between the thought of one object and the thought of another is no more a break in the thought than a joint in a bamboo is a break in the wood. William James described consciousness as a stream – a continuous succession of experiences. For William James consciousness is something flowing uninterruptedly.
The basic problem of existence, according to the Yoga Sutras, is that one is in ignorance of and separated from pure consciousness (Sedlmeier et al., 2012). Meditation is pure consciousness without objectification. Meditation practice is geared to reach higher consciousness. A.K Nair of the Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences Bengaluru, India indicates that Meditation induces a modified state of consciousness that remains under voluntary control.
Meditative consciousness is characterized by receptive attention to and awareness of present events and experiences. It constitutes the ability to become aware of mental activities such as sensations, images, feelings, and thoughts, and to disengage from judgment, conditioned emotions, and their cognitive processing or automatic inhibition (Gartenschläger et al., 2017). In meditative consciousness there are no cognitive elaborations or emotional reactivity. This state is characterized by improved task performance and decreased stress-related symptomolog and without maladaptive mental processes. Some experts state that in meditative consciousness brain activation in the left prefrontal cortex can be detected via functional magnetic resonance imaging.
Ruwan M Jayatunge M.D.