Damasio's theory of consciousness

According to Damasio's theory of consciousness, the protoself is the first stage in the hierarchical process of consciousness generation. Shared by many species, the protoself is the most basic representation of the organism, and it arises from the brain's constant interaction with the body. The protoself is an unconscious process that creates a "map" of the body's physiological state, which is then used by the brain to generate conscious experience. This "map" is constantly updated as the brain receives new stimuli from the body, and it forms the foundation for the development of more complex forms of consciousness.

Damasio asserts that the protoself is signified by a collection of neural patterns that are representative of the body's internal state. The function of this 'self' is to constantly detect and record, moment by moment, the internal physical changes that affect the homeostasis of the organism.[2] Protoself does not represent a traditional sense of self; rather, it is a pre-conscious state, which provides a reference for the core self and autobiographical self to build from. As Damasio puts it, "Protoself is a coherent collection of neural patterns, which map moment-by-moment the state of the physical structure of the organism" (Damasio 1999).[1]

Multiple brain areas are required for the protoself to function. Namely, the hypothalamus, which controls the general homeostasis of the organism, the brain stem, whose nuclei map body signals, and the insular cortex, whose function is linked to emotion. These brain areas work together to keep up with the constant process of collecting neural patterns to map the current status of the body's responses to environmental changes. The protoself does not require language in order to function; moreover, it is a direct report of one's experience. In this state, emotion begins to manifest itself as second-order neural patterns located in subcortical areas of the brain.[1] Emotion acts as a neural object, from which a physical reaction can be drawn. This reaction causes the organism to become aware of the changes that are affecting it. From this realization, springs Damasio's notion of “feeling”. This occurs when the patterns contributing to emotion manifest as mental images, or brain movies. When the body is modified by these neural objects, the second layer of self emerges.[1] This is known as core consciousness.

Sufficiently more evolved is the second layer of Damasio's theory, Core Consciousness. This emergent process occurs when an organism becomes consciously aware of feelings associated with changes occurring to its internal bodily state; it is able to recognize that its thoughts are its own, and that they are formulated in its own perspective.[1] It develops a momentary sense of self, as the brain continuously builds representative images, based on communications received from the Protoself.[1] This level of consciousness is not exclusive to human beings and remains consistent and stable throughout the lifetime of the organism[3] The image is a result of mental patterns which are caused by an interaction with internal or external stimulus. A relationship is established, between the organism and the object it is observing as the brain continuously creates images to represent the organism's experience of qualia.

Damasio's definition of emotion is that of an unconscious reaction to any internal or external stimulus which activates neural patterns in the brain.[1] ‘Feeling’ emerges as a still unconscious state which simply senses the changes affecting the Protoself due to the emotional state. These patterns develop into mental images, which then float into the organism's awareness. Put simply, consciousness is the feeling of knowing a feeling. When the organism becomes aware of the feeling that its bodily state (Protoself) is being affected by its experiences, or response to emotion, Core Consciousness is born. The brain continues to present nonverbal narrative sequence of images in the mind of the organism, based on its relationship to objects. An object in this context can be anything from a person, to a melody, to a neural image. Core consciousness is concerned only with the present moment, here and now. It does not require language or memory, nor can it reflect on past experiences or project itself into the future.

When consciousness moves beyond the here and now, Damasio's third and final layer emerges as Extended Consciousness. This level could not exist without its predecessors, and, unlike them, requires a vast use of conventional memory. Therefore, an injury to a person's memory center can cause damage to their extended consciousness, without hurting the other layers. The autobiographical self draws on memory of past experiences which involves use of higher thought.[4] This autobiographical layer of self is developed gradually over time. Working memory is necessary for an extensive display of items to be recalled and referenced. Linguistic areas of the brain are activated to enhance the organism's experience, however, according to the language of thought hypothesis, language would not be necessarily required.

Damasio's theory of consciousness has been met with criticism for its lack of explanation regarding the generation of conscious experiences by the brain. Researchers have posited that the brain's interaction with the body alone cannot account for the complexity of conscious experience, and that additional factors must be considered. Furthermore, the theory has been criticized for its inadequate treatment of the concept of self-awareness and its lack of a clear method of measuring consciousness, which hinders empirical testing and evaluation.