Changes

Brains can be extremely complex. The human brain contains roughly 100 billion [[neuron]]s, linked with up to 10,000 synaptic connections each.  These neurons communicate with one another by means of long protoplasmic fibers called [[axon]]s, which carry trains of signal pulses called action potentials to distant parts of the brain or body and target them to specific recipient cells.

Brains can be extremely complex. The human brain contains roughly 100 billion [[neuron]]s, linked with up to 10,000 synaptic connections each.  These neurons communicate with one another by means of long protoplasmic fibers called [[axon]]s, which carry trains of signal pulses called action potentials to distant parts of the brain or body and target them to specific recipient cells.

From a philosophical point of view, it might be said that the most important function of the brain is to serve as the physical [[structure]] underlying the mind.  From a biological point of view, though, the most important function is to generate [[behavior]]s that promote the welfare of an animal.  Brains control behavior either by activating muscles, or by causing secretion of chemicals such as hormones. Even single-celled organisms may be capable of extracting information from the environment and acting in response to it. Sponges, which lack a central nervous system, are capable of coordinated body contractions and even locomotion. In vertebrates, the spinal cord by itself contains neural circuitry capable of generating reflex responses as well as simple motor patterns such as swimming or walking.  However, sophisticated control of behavior on the basis of complex sensory input requires the information-integrating capabilities of a centralized brain.

From a philosophical point of view, it might be said that the most important function of the brain is to serve as the physical [[structure]] underlying the mind.  From a biological point of view, though, the most important function is to generate [[behavior]]s that promote the welfare of an animal.  Brains control behavior either by activating muscles, or by causing secretion of chemicals such as hormones. Even single-celled organisms may be capable of extracting information from the environment and acting in response to it. Sponges, which lack a central nervous system, are capable of coordinated body contractions and even locomotion. In vertebrates, the spinal cord by itself contains neural circuitry capable of generating reflex responses as well as simple motor patterns such as swimming or walking.  However, sophisticated control of behavior on the basis of complex sensory input requires the information-integrating capabilities of a centralized brain.