From single source to several parts of brain. Reverberating circuits- circular route. Role in memory storage. Nerve cell bodies are arranged into ganglia. Trend toward greater complexity.
More complex brains have further divisions.
The Human Brain 1. Midbrain a. Superior and inferior colliculi function in visual and auditory systems. Basal ganglia- centers for motor coordination Emotions depend on interaction between cerebral cortex and limbic system. Programs motor cortex to move lips, tongue, speech muscles. The Ear Balance- semicircular canals.