Editing Brain (section)

=== Perception ===
[[File:Hearing mechanics cropped.jpg|thumb|right|alt=Drawing showing the ear, inner ear, and brain areas involved in hearing. A series of light blue arrows shows the flow of signals through the system.|Diagram of signal processing in the [[auditory system]]]]

The human brain is provided with information about light, sound, the chemical composition of the atmosphere, temperature, the position of the body in space ([[proprioception]]), the chemical composition of the bloodstream, and more. In other animals additional senses are present, such as the [[Infrared sensing in snakes|infrared heat-sense of snakes]], the [[Magnetoception|magnetic field sense]] of some birds, or the [[Electroreception|electric field sense]] mainly seen in aquatic animals.

Each sensory system begins with specialized receptor cells,<ref name="Kandel 2000"/><!--Ch. 21--> such as [[photoreceptor cell]]s in the [[retina]] of the [[eye]], or vibration-sensitive [[hair cell]]s in the [[cochlea]] of the [[ear]]. The axons of sensory receptor cells travel into the spinal cord or brain, where they transmit their signals to a [[sensory system|first-order sensory nucleus]] dedicated to one specific [[Stimulus modality|sensory modality]]. This primary sensory nucleus sends information to higher-order sensory areas that are dedicated to the same modality. Eventually, via a way-station in the [[thalamus]], the signals are sent to the cerebral cortex, where they are processed to extract the relevant features, and [[Multisensory integration|integrated]] with signals coming from other sensory systems.<ref name="Kandel 2000"/><!--Ch. 21-->