The Eyes of The Body: perception, sensoriality and neuroarchitecture

By Andréa de Paiva

Have you ever thought how would the world be without the sense of vision? How would people enjoy watching a dance performance or observing a painting? What would be the beauty patterns? How would we relate to each other? With which groups would we identify ourselves? In today's article we will discuss how we use the senses in order to relate with the world through the lens of NeuroArchitecture.

Eye in the hand. Source:

Since ancient times, the sense of vision is very appreciated. Philosophers like

Heráclitus, Plato and Aristotle discussed on their work the importance of vision in comparison with the other senses. As years passed by, the development of new technologies like the printed press, photography and the computer impelled us to become even more dependent of vision. Expressions like "seeing is believing" or "in the land of the blind the one-eyed man is king" illustrate how this sense is overestimated.

But is vision really our most important sense? To answer this question, let's analyse briefly how the brain processes the information brought by the sensorial organs.

Our brain dedicates around 30% of its cortex to process vision. This means that this sense uses a lot of energy and occupies a large portion of the brain. Besides, vision is not processed equally on the region. On the contrary, this area is divided in especialized sub-zones. Each one of them has a specific function, such as identify shapes, objects location, colours and even human faces. Furthermore, neuroscience has already proved that the cerebral cortex is not the only area involved with vision processing. More primitive regions, like the amygdala, are also involved, helping to identify and react to facial expressions, specially those that can mean threat, like anger [1].

In spite of dedicating so much space and energy to vision processing and of the expression "seeing is believing", vision is not always that reliable. There are many optical illusions that trick this sense, for instance the famous dress that some people saw black and blue and others as white and gold. Vision is not the only sense we use to perceive the world that surrounds us and, maybe, it is not even the most important for the brain.

Hearing is our sense with the largest reach. Depending on the intensity of the sound, it can be heard miles away. Besides, some sounds can influence brain waves [2], emotions, heart beatings and breathing [3]. Some songs, for instance, can help relaxing, while others can make us more alert and agitated. Others might even cause goose bumps or make us cry and feel emotional. But not only music impacts the brain and behavior. Constant sound pollution can have severe impacts on health and well being, affecting the circadian rhythm (our biological clock), breathing rhythm, cognition and even heart beatings.

The sense of smell, in its turn, is one of our oldest senses. It has the important role of helping us to find food. Often we do not need to see the restaurant in the corner of the street to know that they are preparing a juicy steak. We feel the smell and automatically our stomach starts to rumble and it gets harder to concentrate on what we were doing before. This happens because the smell activates the hypothalamus, which helps to control, among other things, hunger. But this sense importance goes beyond that. It is not useful to find food if we are not able to analyse if it is rotten or not. This is why we are so sensitive to bad smells, feeling disgusted and usually getting away as soon as possible from it.

The area where this sense is processed is also directly connected with important regions of the brain, like the hippocampus (responsible for memory processing) and the amygdala (responsible for emotions processing and motivation) [4]. That is why when we feel some specific smell, like one from our childhood, memories from that time come back automatically, for instance.

Touch is another sense that is also very old and the first to develop when the baby is in the uterus. Furthermore, it has the largest sensory organ among all others: the skin. As it has been discussed for a long time, touch's relevance goes beyond the perception of what is happening around