Del capítulo sobre la mente de E. O. Wilson, Consilience, describiendo
cómo la mente es un sistema de representaciones, guiones situacionales
y escenarios organizados, que conjuntamente constituyen una especie de
realidad virtual... para ningún espectador. El espectador sería más
bien el efecto resultante de la interacción de estos sistemas
cerebrales.
Mind
is a stream of conscious and subconscious experience. It is at root the
coded representation of sensory impressions and the memory and
imagination of sensory impressions. The information composing it is
most likely sorted and retreived by vector coding, which denotes
direction and magnitude. For example, a particular taste might be
partly classified by the combined activity of nerve cells responding to
different degrees of sweetness, saltiness, and sourness. If the brain
were designed to distinguish ten increments in each of these taste
dimensions, the coding could discriminate 10 x 10 x 1, or 1,000
substances.
Consciousness consists of the parallel processing of vast numbers of such coding networks. Many are linked by the synchronized firing of the nerve cells at forty cycles per second, allowing the simultaneous internal mapping of multiple sensory impressions. Some of the impressions are real, fed by ongoing stimulation from outside the nervous system, while others are recalled from the memory banks of the cortex. All together they create scenarios that flow realistically back and forth through time. The scenarios are a virtual reality. They can either closely match pieces of the external world or depart indefinitely far from it. They re-create the past and cast up alternative futures that serve as choices for future thought and bodily action. The scenarios comprise dense and finely differentiated patterns in the brain circuits. When fully open to input from the outside, they correspond well to all the parts of the environment, including activity of the body parts, monitored by the sense organs.
What or what within the brain monitors all this activity? no one. Nothing. the scenarios are not seen by some other part of the brain. They just are. Consciousness is the virtual world composed by the scenarios. There is not even a Cartesian theater, to use Daniel Dennett's dismissive phrase, no single locus of the brain where the scenarios are played out in coherent form. Instead, there are interlacing patterns of neural activity within and among particular sites throughout the forebrain, from cerebral cortex to other specialized centers of cognition such as the thalamus, amygdala, and hippocampus. There is no single stream of consciousness in which all information is brought together by an executive ego. There are instead multiple streams of activity, some of which contribute momentarily to conscious thought and then phase out. Consciousness is the massive coupled aggregates of such participating circuits. The mind is a self-organizing republic of scenarios that individually germinate, grow, evolve, disappear, and occasionally linger to spawn additional thought and physical activity.
The neural circuits do not turn on and off like parts of an electrical grid. In many sectors of the forebrain at least, they are arranged in parallel relays stepping from one neuron level to the next, integrating more and more coded information with each step. The energy of light striking the retina, to expand the example I gave earlier, is transduced into patterns of neuron firing. The patterns are relayed through a sequence of intermediate neuron systems out of the retinal fields through the lateral geniculate nuclei of the thalamus back to the primary visual cortex at the rear of the brain. Cells in the visual cortex fed by the integrated stimuli sum up the information from different parts of the retina. They recognize and by their own pattern of firing specify spots or lines. Further systems of these higher-order cells integrate the information from multiple feeder cells to map the shape and movement of objects. In ways still not understood, this pattern is coupled with simultaneous input from other parts of the brain to create the full scenarios of consciousness. The biologist S. J. Singer has drily expressed the matter thus: I link, therefore I am. (110)
Consciousness consists of the parallel processing of vast numbers of such coding networks. Many are linked by the synchronized firing of the nerve cells at forty cycles per second, allowing the simultaneous internal mapping of multiple sensory impressions. Some of the impressions are real, fed by ongoing stimulation from outside the nervous system, while others are recalled from the memory banks of the cortex. All together they create scenarios that flow realistically back and forth through time. The scenarios are a virtual reality. They can either closely match pieces of the external world or depart indefinitely far from it. They re-create the past and cast up alternative futures that serve as choices for future thought and bodily action. The scenarios comprise dense and finely differentiated patterns in the brain circuits. When fully open to input from the outside, they correspond well to all the parts of the environment, including activity of the body parts, monitored by the sense organs.
What or what within the brain monitors all this activity? no one. Nothing. the scenarios are not seen by some other part of the brain. They just are. Consciousness is the virtual world composed by the scenarios. There is not even a Cartesian theater, to use Daniel Dennett's dismissive phrase, no single locus of the brain where the scenarios are played out in coherent form. Instead, there are interlacing patterns of neural activity within and among particular sites throughout the forebrain, from cerebral cortex to other specialized centers of cognition such as the thalamus, amygdala, and hippocampus. There is no single stream of consciousness in which all information is brought together by an executive ego. There are instead multiple streams of activity, some of which contribute momentarily to conscious thought and then phase out. Consciousness is the massive coupled aggregates of such participating circuits. The mind is a self-organizing republic of scenarios that individually germinate, grow, evolve, disappear, and occasionally linger to spawn additional thought and physical activity.
The neural circuits do not turn on and off like parts of an electrical grid. In many sectors of the forebrain at least, they are arranged in parallel relays stepping from one neuron level to the next, integrating more and more coded information with each step. The energy of light striking the retina, to expand the example I gave earlier, is transduced into patterns of neuron firing. The patterns are relayed through a sequence of intermediate neuron systems out of the retinal fields through the lateral geniculate nuclei of the thalamus back to the primary visual cortex at the rear of the brain. Cells in the visual cortex fed by the integrated stimuli sum up the information from different parts of the retina. They recognize and by their own pattern of firing specify spots or lines. Further systems of these higher-order cells integrate the information from multiple feeder cells to map the shape and movement of objects. In ways still not understood, this pattern is coupled with simultaneous input from other parts of the brain to create the full scenarios of consciousness. The biologist S. J. Singer has drily expressed the matter thus: I link, therefore I am. (110)
Querría yo apuntar una cuestión que a veces no se distingue bien, la diferencia entre consciencia y atención. (La atención a la propia atención, o la atención a la consciencia, sería sólo un problema derivado de esta diferencia básica).
Definida a la manera de Wilson, la experiencia consciente es multilinear, multinivel, una experiencia simultánea del cuerpo y del entorno, constituida por la interacción de los sistemas neurales procedentes de la percepción y de los activados por la memoria o el pensamiento "offline", cuando éste existe.
A mayor complejidad de los circuitos cerebrales, mayor variedad y complejidad potencial de la consciencia, por la multiplicidad de niveles en interacción y por la multiplicidad o rapidez de cambios posibles de un escenario a otro. Esta cuestión también tiene que ver con la atención, pero no puede la atención reducirse únicamente a la complejidad de la consciencia. Una consciencia menos compleja que otra puede estar sin embargo atenta a un determinado fenómeno. La atención no queda bien descrita en el párrafo anterior (no creo que se plantease tampoco Wilson describir la atención, quizá ni lo conciba como problema). La atención tiene menos que ver con la complejidad de los múltiples planos, circuitos, y escenarios, como con la selección de uno en concreto entre varios. Yo la asocio a una cuestión de retroalimentación y reflexividad: la atención se fija precisamente mediante un proceso de centrado, no de fluir entre diversos planos o niveles—manteniendo uno de ellos en retroalimentación por así decirlo. La atención a un objeto de percepción se enriquece con el conocimiento conceptual de este objeto; la atención en el pensamiento offline o en la imaginación es asimismo un proceso de repetición, si no de retroalimentación entre el objeto de atención y la nueva activación conceptual que se le dedica. Así pues es creíble que no haya nadie pilotando nuestra consciencia, pero sin embargo sí hay un elemento dinámico en fijar y mantener la atención. Seguramente la atención es más compleja en los seres humanos, del mismo modo que es más compleja la consciencia. Pero sería útil examinar más de cerca estos conceptos, tanto en las relaciones que los unen como en sus diferencias—pues no estamos atentos a todos los contenidos de nuestra consciencia; la atención es una especie de hiper-consciencia, y mantiene con ella una relación similar a la que diferencia la fóvea del resto de la retina. Un estudio comparado de retinas sería un buen lugar por donde empezar a investigar estas cuestiones.
También es posible que haya, cómo no, un lugar de la consciencia similar al punto ciego de la retina.
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