Developed in his (1999) book, 'The Feeling of What Happens', Antonio Damasio's three layered theory of consciousness is based on a hierarchy of stages, with each stage building upon the last. The most basic representation of the organism is referred to as the Protoself, next is Core Consciousness, and finally, Extended Consciousness. Damasio, who is an internationally recognized leader in neuroscience, was educated at the University of Lisbon and currently directs the University of Southern California Brain and Creativity Institute. Damasio's approach to explaining the development of consciousness relies on three notions: emotion, feeling, and feeling a feeling. Emotions are a collection of unconscious neural responses to qualia. These complex reactions to stimuli cause observable external changes in the organism. A feeling arises when the organism becomes aware of the changes it is experiencing as a result of external or internal stimuli.
Our most basic representation of self, as Damasio dubs it, is the Protoself. A non conscious state, this level of self is shared by all manner of life forms, even single celled organisms. This is the most basic level of awareness 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. 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).
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.