Regions identified in chordate brains include:

Function:

Vertebrate brains receive signals through nerves arriving from most portions of a body, interpret those signals and formulate reactions based on prior experiences and on physical needs. A similarly extensive nerve network delivers signals from a brain to control muscles throughout a body.

Sensory input is processed by the brain to recognize danger, find food, and identify potential mates, among other goals. Visual, touch, and auditory sensory pathways of vertebrates are routed to the thalamus and then to regions of the cerebral cortex that are specific to each sensory system: the visual system, the auditory system and the somatosensory system. Olfactory pathways are routed to the olfactory bulb, then to various parts of the olfactory system. Taste is routed through the brainstem and then to other portions of the gustatory system.

To control movement, the brain has several parallel systems of muscle control. The motor system controls voluntary muscle movement, aided by feedback loops in the cerebellum and the basal ganglia. Nuclei in the brainstem control many involuntary muscle functions such as heartrate and breathing.

Brains also produce hormones that can influence organs elsewhere in a body and brains react to hormones produced elsewhere in the body. In mammals, most of these hormones are released into the circulatory system by a structure called the pituitary gland.

It is hypothesized that developed brains derive consciousness from interaction among numerous systems within the brain. Cognitive processing in mammals occurs in the cerebral cortex but relies on mid-brain and limbic functions as well, especially those of the thalamus and hippocampus. Among vertebrates, sensory processing involves progressively rostral regions of the brain among newer species.

Hormones, sensory information, autonomic processes, and cognitive processes alike can exert strong influence on the regulation of brain activities. Stimulus from any source can trigger a general arousal process that decreases reliance on cortical processes, or that enhances and focuses cortical processes. Such diverse causes as hunger, fatigue, beliefs, unfamiliar information or actual threats can trigger an alert response that can exert control over cognitive priorities.