Consciousness from the Viewpoint of the Structural‐functional Relationships of the Brain

The brain of vertebrates consists of brainstem and spinal cord conducting reflexes, compound movements, and innate behaviour, and the cerebral neocortex generating sensorimotor function and association function. These five major functions are assisted by four regulatory systems: limbic system, basal ganglia, cerebellum and sleep‐wakefulness brainstem centres. Consciousness contains three different levels, i.e., wakefulness, awareness and self‐consciousness. Wakefulness is a fundamental brain function regulated by the brainstem wakefulness centres. Awareness represents integration of diverse sensory signals, largely in the neocortex, for the perception of what is going on in the external world. Consciousness in humans is directed to the self so that an individual is aware of what is going on in his or her internal world, i.e., the mind, and seems to be inherent to the association cortex, in particular the frontal lobe. Freud's id emerges from the hypothalamus and limbic system, whereas the ego involves both the sensorimotor and association cortices. The super‐ego is likely to be embodied in part of the association cortex. When movement and thought are conceived as a control system function, instruction for control corresponds to the will which initiates these actions and which represents a positive aspect of consciousness. Though consciousness is related to brain structures in these ways, a crucial question remains as to how we subjectively experience will, affect or self‐consciousness as a consequence of neuronal activities in the brain structures.