Shamans of the Piaroa ethnic group (southern Venezuela) conceive of power in terms of knowledge derived from visionary experiences. Märipa is an epistemology concerning the translation of knowledge derived from the integrative mode of consciousness, induced primarily through the consumption of plant hallucinogens, to practical effect during waking life. I integrate mythological, neurobiological, experiential, and ethnographic data to demonstrate what märipa is, and how it functions. The theory and method of märipa underlie not only Piaroa shamanic activity, but all aspects (...) of Piaroa life; mythology, causality, eschatology, and history. Piaroa shamanic practices involve conditioning the mind to achieve optimal perceptual capacities that facilitate accurate prediction and successful psycho‐social prescription. Piaroa shamans describe their technologies of consciousness in terms of gods and spirits, but also in terms of studying and the acquisition of information. Because neurobiological processes underlie the development and experience of märipa, the language of neurobiology enables a partial translation of this indigenous epistemology. The concepts of feed forward neural processing and somatic markers are central to the processes of mental imagery cultivation that Piaroa shamans employ to divine solutions to adaptive problems. Piaroa 'techniques of ecstasy' involve the ability to apply mythological templates of human adaptation to schemas of human behaviour based on years of social analysis in association with heightened information processing capacities derivative of refined experimentation with the integrative mode of consciousness. Keyordsshamanism, neurophenomenology inugrativeconsciousness, hallucinogens. (shrink)

Many have claimed that split-brain patients are actually two persons. I maintain that both the traditional separation argument and the more recent sophistication argument for the two persons interpretation are inadequate on conceptual grounds. An autonomy argument is inadequate on empirical grounds. Overall, theoretical and practical consequences weigh heavily in favor of adopting a one person interpretation.

A technique for the bilateral activation of neural nets that leads to a functional asymmetry of two simulated ''cerebral hemispheres'' is described. The simulation is designed to perform object recognition, while exhibiting characteristics typical of human consciousness-specifically, the unitary nature of conscious attention, together with a dual awareness corresponding to the ''nucleus'' and ''fringe'' described by William James (1890). Sensory neural nets self-organize on the basis of five sensory features. The system is then taught arbitrary symbolic labels for a small (...) number of similar stimuli. Finally, the trained network is exposed to nonverbal stimuli for object recognition, leading to Gaussian activation of the ''sensory'' maps-with a peak at the location most closely related to the features of the external stimulus. ''Verbal'' maps are activated most strongly at the labeled location that lies closest to the peak on homologous sensory maps. On the verbal maps activation is characterized by both excitatory and inhibitory Gaussians (a Mexican hat), the parameters of which are determined by the relative locations of the verbal labels. Mutual homotopic inhibition across the ''corpus callosum'' then produces functional cerebral asymmetries, i.e., complementary activation of homologous ''association'' and ''frontal'' maps within a common focus of attention-a nucleus in the left hemisphere and a fringe in the right hemisphere. An object is recognized as corresponding to a known label when the total activation of both hemispheres (nucleus plus fringe) is strongest for that label. The functional dualities of the cerebral hemispheres are discussed in light of the nucleus/fringe asymmetry. (shrink)

The traditional verbal/nonverbal dichotomy is inadequate for completely describing cerebral lateralization. Musical functions are not necessarily mediated by the right hemisphere; evidence for a specialist left-hemisphere mechanism dedicated to the encoded speech signal is weakening, and the right hemisphere possesses considerable comprehensional powers. Right-hemisphere processing is often said to be characterized by holistic or gestalt apprehension, and face recognition may be mediated by this hemisphere partly because of these powers, partly because of the right hemisphere's involvement in emotional affect, and (...) possibly through the hypothesized existence of a specialist face processor or processors in the right. The latter hypothesis may, however, suffer the same fate as the one relating to a specialist encodedness processor for speech in the left. Verbal processing is largely the province of the left because of this hemisphere's possession of sequential, analytic, time-dependent mechanisms. Other distinctions are special cases of an analytic/holistic dichotomy. More fundamentally, however, the left hemisphere is characterized by its mediation of discriminations involving duration, temporal order, sequencing, and rhythm, at thesensory level, and especially at themotorlevel. Spatial aspects characterize the right, the mapping of exteroceptive body space, and the positions of fingers, limbs, and perhaps articulators, with respect to actual and target positions. Thus there is a continuum of function between the hemispheres, rather than a rigid dichotomy, the differences being quantitative rather than qualitative, of degree rather than of kind. (shrink)