Visual perception

Human perception (from Latin: percepio, from percipere; to perceive) is the bridge that links our sensations and consciousness (ego) to the real world (reality). This bridge is built trough the multisensory integration process that our nervous system performs with all the signals generated by our senses. In Ancient Greece, philosophers were curious to discover the correspondence between ‘reality’ and our mental image of the world (‘our’ world). Plato called ‘’phantasma’’ (phantom) our mental image of a real thing (in front of us) as perceived and distorted by our senses. Since then human perception has been studied, but along the last century, it was the object of systematic multidisciplinary research. Since Santiago Ramon y Cajal and Camilo Golgi obtained in 1906 The Nobel Prize in Physiology by discovering a method to colorize the nervous tissues (initiating neuroanatomy), the nervous system and the brain have been the object of perhaps the broadest scientific literature. However, still, our knowledge about them remains limited.

Perception is linked to signal analysis and processing in many aspects. When we try to explore these fields, we have to use Psychophysics. This scientific methodology has contributed many fundamental advances in determining perception and discrimination thresholds of our senses, performing the evaluation of its mental representations as well.  In addition to the psychophysical methodology for studying perceptions, another important role was played by Electronics along with Computer Science. Both influenced our understanding of the neural system from their specific points of view. They helped with the detection of the neuronal electrical activity and with the simulation of the neuronal behavior.

In our Laboratory we are mainly focusing on the study of visual perception that is the faculty to see, inspect and make sense to all nearby visual information (entering as visible electromagnetic energy reflected from all physical objects encircling us).

The visual system consists of several physiological elements from the cornea to the primary visual cortex. Human seeing begins when light enters the cornea, gets focused at the back of the eye in a susceptible membrane known as the retina. Specifically, the light is focused on the photoreceptive cells (rods and cones) of the retina. The photoreceptors then transduce the light into neuronal signals. These signals are treated via complex feedback and feedforward processes by distinct parts of the brain, beginning from the retina, central ganglia to the visual association cortex. The visual association cortex allows the entire visual scene, thus object’s perception.

We have studied different elements involved in visual perception from the eye to behavior. For instance, we have investigated visual perception with the help of psychophysics and using first order (luminance based) and second order (contrast based) Gabor patches. These studies have helped us to understand basic detection mechanisms in different human populations such as the elderly and autism or to comprehend better the principles on how vision integrates with other senses (auditory and tactile).

Past and ongoing projects

  • Déficits de perception visuelle chez les adultes suite à un traumatisme crânio-cérébral léger : psychophysique, électrophysiologie et impact sur la stabilité posturale