General intelligence doesn’t depend on specific brain areas at all, and just has to do with how the whole brain functions. ~ American psychologist and neurobiologist Ralph Adolphs
When one exists, an animal’s brain harbors the control physiology for much of its body. The brain exerts centralized regulation over other body organs via nervous system conduction.
Prototype brain circuits originated very early and have been maintained across animal species throughout evolutionary time. There are deep similarities between our brains and those of insects. ~ English neurobiologist Frank Hirth
Though the brain acts as an entangled organ, there are processing loci within for certain functions. This provides an evolutionary advantage in being able to perform separate tasks simultaneously (parallel processing), such as autonomic functioning and various forms of mentation. For instance, the hypothalamus regulates the autonomic nervous system. During localized activity, other portions of the brain are actively contributing, albeit less intensely.
Many brain communications are chemical, not electrical (as well as always being energetic). Calcium waves play a key role in the physiological correlate to cognition and memory.
The brain acts on the body by driving chemical secretions and generating muscle activity patterns. Simple responses, such as reflexes, are mediated in the spinal cord or peripheral glia. More complex perception and behaviors involve the central brain.
All we ever observe is the concomitant variations or correlations between states of the brain and states of the mind. Correlation is not causation. ~ American physician Larry Dossey