Sinnessystems

Sinnessystems, or sensory systems, are the networks of receptors, neural pathways and brain regions that detect, relay and interpret information about the external world and the body’s internal state. They are commonly categorized into exteroceptive systems, which monitor external stimuli such as sight, hearing, taste, smell and touch; interoceptive systems, which sense internal bodily conditions; and proprioceptive systems, which provide information about body position and movement.

The main modalities include visual, auditory, somatosensory, gustatory, olfactory and vestibular systems, with additional modalities such as thermoception (temperature) and nociception (pain). Sensory transduction begins at specialized receptors (for example, photoreceptors in the retina, hair cells in the inner ear, mechanoreceptors in the skin, and chemoreceptors for taste and smell). The resulting neural signals travel via peripheral nerves and cranial nerves to the brain, where they are relayed through the thalamus to dedicated primary cortical areas (for instance, visual cortex for sight, auditory cortex for hearing, primary somatosensory cortex for touch) and then to higher-order association areas for interpretation and integration.

Multisensory integration combines information across modalities to form coherent percepts and guide behavior. This integration occurs in various brain regions, including parts of the parietal and temporal lobes, as well as subcortical structures such as the superior colliculus.

Clinical relevance includes sensory impairments (deafness, blindness, neuropathies), altered perceptions (phantom sensations, synesthesia) and the brain’s plastic response to changes in sensory input.