8.1: Introduction

Austin Lim, PhD (DePaul University)

Editor: Alexander Rajan, PhD

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Our nervous system is equipped with a variety of specialized biological “tools” that can detect much more than just photons of light. We can detect the shape of air waves, and interpreting those signals give us sound information and the perception of music. We can detect stimuli with our skin, such as temperature, pressure, and textures. We can also detect physical information about our own bodies, as in the way our head is tilted or the position of our limbs. In this chapter, we describe these other forms of physical stimuli, and how that information is conveyed to and represented in the brain.

All sensory systems, including vision (Chapter 7) and the systems described below, follow the same general path of communication into our nervous systems and awareness. First, the incoming signal must reach a cell (generally called a transducer) that can change its electrical properties in response to the stimulus (such as a retinal photoreceptor cell responding to photons). Then, that information initiates a series of signals into the CNS, reaching structures such as the thalamus (in most cases; olfaction being an exception), primary sensory cortical areas, and finally, higher order perception. Although there are several sensory components throughout our body that detect these signals, there are no sensory receptors in our central nervous system.

As we discuss sensory and perception further, it’s good to keep in mind that not all sensations are perceived. For example, your body can detect changes in blood pressure, and your brain responds to these changes activating compensatory neural circuits. However, this response does not reach consciousness and are not perceived.

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