ABSTRACT
Bi-stable perception is a strong instance of cognitive self-organization, providing a research model for how 'the brain makes up its mind.' The complexity of perceptual bistability prevents a simple attribution of functions to areas, because many cognitive processes, recruiting multiple brain regions, are simultaneously involved. The functional magnetic resonance imaging (fMRI) evidence suggests the activation of a large network of distant brain areas. Concurrently, electroencephalographic and magnetoencephalographic (MEEG) literature shows sub second oscillatory activity and phase synchrony on several frequency bands. Strongly represented are beta and gamma bands, often associated with neural/cognitive integration processes. The spatial extension and short duration of brain activities suggests the need for a fast, large-scale neural coordination mechanism. To address the range of temporo-spatial scales involved, we systematize the current knowledge from mathematical models, cognitive sciences and neuroscience at large, from single-cell- to system-level research, including evidence from human and non-human primates. Surprisingly, despite evidence spanning through different organization levels, models, and experimental approaches, the scarcity of integrative studies is evident. In a final section of the review we dwell on the reasons behind such scarcity and on the need of integration in order to achieve a real understanding of the complexities underlying bi-stable perception processes.
ABSTRACT
RESUMEN En la investigación de la percepción visual comúnmente se usan programas computarizados comerciales para la presentación de los estímulos, configurados por lo general para admitir una respuesta por cada estímulo presentado. Sin embargo, el estudio de la percepción multiestable, requiere la presentación de un estímulo que permanece invariable aunque la percepción de éste puede variar en dos o más configuraciones, lo que demanda que el programa admita respuestas para cada cambio en la percepción de un mismo estímulo. Se presenta PercepFiguras desarrollado con lenguaje de programación C++ que es un sistema de estimulación visual que permite al usuario: a) presentar imágenes y recibir una o varias respuestas a cada una, b) sincronizar las respuestas con un sistema de registro electroencefalográfico mediante el envío de pulsos TTL, c) generar un archivo conductual y d) generar un archivo con el total de respuestas y promedios de las latencias a cada tipo de figura. Se realizó un estudio piloto con una tarea de presentación continua de una figura ambigua alternando con dos variantes de menor ambigüedad, se obtuvo mayor frecuencia de cambios perceptuales y menor estabilidad perceptual para la figura ambigua respecto a las de menor ambigüedad, comprobándose la utilidad del programa.
ABSTRACT In the study of visual perception, the use of computerized commercial programs for the presentation of stimuli, usually configured to admit a response for each stimulus presented, is common. However, the study of multistable perception requires the presentation of a stimulus that remains unchanged, although the perception of it can vary in two or more configurations during its observation, which demands that the program admit responses for each change in perception of the same stimulus. PercepFiguras is a system developed with C++ programming language that allows: a) present images and receive multiple responses to the same stimulus, b) synchronize the responses with an electroencephalographic recording system by sending TTL pulses, c) generate a behavioral file, d) generate a file with the total responses and averages of the latencies for each type of figure. In the pilot study with a task of continuous presentation of an ambiguous figure to alternating with two variants of less ambiguity, we observe greater frequency of perceptual and less perceptual stability to the ambiguous figure with respect to the less ambiguous figures, which proves the usefulness of the program.