A Computational Model for Conscious Visual Perception and Figure/Ground Separation

Abstract

Abstract:The human brain is able to perform a number feats that researchers have not been able to replicate in artificial systems. Unsolved questions include: Why are we conscious and how do we process visual information from the input stimulus right down to the individual action. We have created a computational model of visual information processing. A network of spiking neurons, a single layer, is simulated. This layer processes visual information from a virtual retina. In contrast to the standard integrate and fire behavior of biological neurons, we focus on lateral connections between neurons of the same layer. We assume that neurons performing the same function are laterally connected through gap junctions. These lateral connections allow the neurons responding to the same stimulus to synchronize their firing behavior. The lateral connections also enable the neurons to perform figure/ground separation. Even though we describe our model in the context of visual information processing, it is clear that the methods described, can be applied to other kinds of information, e.g. auditory. MOTIVATIONTo fully understand how cognitive information processing works, we will have to replicate all essential functions of the brain either in simulation or by building an artificial artifact. Only if we are able to build an artificial entity, which is able to perform similar tasks as the human brain, then we have understood how the brain actually works. Sensory perception, motor control and learning are assumed to be a result of the neural processing occurring inside the brain. It is assumed that the processing occurs through so called integrate-and-fire neurons. Such neurons integrate the electrical inputs received through axons from other neurons. Once the activation of a neuron reaches a certain threshold, then it fires. It itself sends an electrical impulse along its axon. An essential marker of consciousness cognition is the synchronized electrical activity of neurons inside a particular frequency band (30 to 90 Hz) of the electroencephalogram (EEG), called gamma synchrony EEG (Gray and Singer, 1989;Ribary et al., 1991). Singer (2007) has put forward the microconsciousness theory. He suggests that multiple consciousnesses are distributed across processing sites and that attributes such as color, form or motion are eventually bound together giving rise to macroconsciousness possibly also involving linguistic and communication skills which would then be a