The Senses and Perception
“We’ve learned there are many brain regions involved in perception.” Marlene Behrmann, Ph.D.
Our five senses – vision, hearing, smell, taste, and touch – are what helps us successfully navigate our world. They help us interpret our environment and understand what’s happening around us.
Each of the five senses has its own unique neural operating system, but they all have remarkable similarities. Each sense organ – the eye, the skin, the nose, the tongue, and the ear – takes in environmental information through specialized cells called sensory receptors. That information is then transformed into electrical signals that can be read by the brain. Those signals are processed in their own respective areas of the brain, and then passed through a part of the brain called the thalamus, which acts as a sensory integrator of sorts, putting all of the information together.
Vision: Our primary sense. The brain devotes more real estate to the processing of visual information than all the other senses combined!!
The lens of the eye transmits light information onto the retina. There, two types of photoreceptor cells, rods and cones, start processing that information and then send it on to the visual cortex, house in the occipital lobe. More than two dozen different specialized cortical areas are involved with visual perception. Together, these visual circuits discriminate size, position, color, and shape – all the qualities and characteristics that allow us to easily recognize everything we see.
Hearing: Inside the ear is the tympanic membrane, otherwise known as the eardrum, and a handful of tiny bones called ossicles. When sounds travel past the eardrum, the ossicles transmit those vibrations to part of the inner called cochlea. The cochlea has specialized cells that pick up those vibrations and then pass auditory signals on to the primary auditory cortex in the brain’s temporal lobe.
Taste: The receptors on the tongue are gathered into taste buds. They pick up molecules and then send signals to the olfactory bulb and on to the piriform cortex and limbic system, the brain’s emotional circuitry.
Touch: Touch receptors can be found all over the body, distributed across the skin. Those receptors are specialized – some respond to touch, some to pressure, and others to temperature. They send those signals up the spinal cord to the brain stem, where they are then sent for processing in the somatosensory cortex, found in the brain’s parietal lobe. These various types of touch signals come together to give us a unified representation of our body in space.
“The big message is how interconnected everything is – brain function is distributed, and there are multiple regions of cortex that work together to give rise to behavior. It’s no longer the case that we think there is one region of the brain that does one thing. Circuitry is the message of the day. And that holds true in perception. We’ve learned that there are many brain regions involved in perception – you can see activity in frontal cortex.” Marlene Behrmann, Ph.D.
