Milner and Goodale's influential account of the primate cortical visual streams involves a division of consciousness between them, for it is the ventral stream that has the responsibility for visual consciousness. Hence, the dorsal visual stream is a ‘zombie’ stream. In this article, I argue that certain information carried by the dorsal stream likely plays a central role in the egocentric spatial content of experience, especially the experience of visual spatial constancy. Thus, the dorsal stream contributes to a pervasive feature (...) of consciousness. (shrink)

By characterizing the function of the ventral and dorsal visual streams as, respectively, vision-for-perception and vision-for-action, Milner and Goodale have brought some action onto the perceptual scene. However, with the distinction of the ventral "what" system and the dorsal "how" system, comes a dilemma: How is the operation of the two systems united toward common goals? This is an example of a binding problem. We propose that for binding these two systems, no mechanism needs to exist in the brain to (...) bring ventral and dorsal representations together. Coherent behavior may be accomplished by focusing the two streams upon the same external object through a strategy of spatial selection, using either the fovea or selective attention. This strategy exploits the simple fact that two objects cannot occupy the same place at the same time. Other kinds of binding, like that involving the perceptual binding of the elements of a scene into coherent perceptual units, may be accomplished by exploiting other regularities of the environment, such as the likelihood that two simultaneous sounds were caused by a common event. From an evolutionary perspective, the most effective way to cope with the distant environment is to use different but complementary sensors, both contributing to aspects of identification and action guidance. For example, audition plays a role both in perceptual analysis and in action guidance, suggesting the possibility of segregated processing of auditory information. Thus, the functional distinction between a "what" system and a "how" system may not be limited to the visual modality, but may be a fundamental distinction for behavioral control in general. (shrink)

Emotion is conscious experience. It is the affective aspect of consciousness. Emotion arises from sensory stimulation and is typically accompanied by physiological and behavioral changes in the body. Hence an emotion is a complex reaction pattern consisting of three components: a physiological component, a behavioral component, and an experiential (conscious) component. The reactions making up an emotion determine what the emotion will be recognized as. Three processes are involved in generating an emotion: (1) identification of the emotional significance of a (...) sensory stimulus, (2) production of an affective state (emotion), and (3) regulation of the affective state. Two opposing systems in the brain (the reward and punishment systems) establish an affective value or valence (stimulus-reinforcement association) for sensory stimulation. This is process (1), the first step in the generation of an emotion. Development of stimulus-reinforcement associations (affective valence) serves as the basis for emotion expression (process 2), conditioned emotion learning acquisition and expression, memory consolidation, reinforcement-expectations, decision-making, coping responses, and social behavior. The amygdala is critical for the representation of stimulus-reinforcement associations (both reward and punishment-based) for these functions. Three distinct and separate architectural and functional areas of the prefrontal cortex (dorsolateral prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex) are involved in the regulation of emotion (process 3). The regulation of emotion by the prefrontal cortex consists of a positive feedback interaction between the prefrontal cortex and the inferior parietal cortex resulting in the nonlinear emergence of emotion. This positive feedback and nonlinear emergence represents a type of working memory (focal attention) by which perception is reorganized and rerepresented, becoming explicit, functional, and conscious. The explicit emotion states arising may be involved in the production of voluntary new or novel intentional (adaptive) behavior, especially social behavior. (shrink)