| − | The '''brain''' is a major part of the [[central nervous system]]. In vertebrates, the brain is connected to the [[spinal cord]]. In [[invertebrate]]s' [[nervous system]]s, the brain can be a decentralized collection of [[neurons]] or a single [[Ganglia|ganglion]]. In the [[vertebrate]]s, the brain is much more complex and is divided into three separate areas, the [[forebrain]], the [[midbrain]], and the [[hindbrain]]. The brain is involved in higher functioning such as decision-making, [[speech]], and processing of the [[senses]]. | + | The '''brain''' is a major part of the [[central nervous system]]. In vertebrates, the brain is connected to the [[spinal cord]]. In [[invertebrate]]s' [[nervous system]]s, the brain can be a decentralized collection of [[neurons]] or a single [[Ganglia|ganglion]]. In the [[vertebrate]]s, the brain is much more complex and is divided into three separate areas, the [[forebrain]], the [[midbrain]], and the hindbrain. The brain is involved in higher functioning such as decision-making, [[speech]], and processing of the [[senses]]. |
| | In adult humans, the brain weighs about 3 lbs., with 100 billion neurons, and up to 100 trillion connections. | | In adult humans, the brain weighs about 3 lbs., with 100 billion neurons, and up to 100 trillion connections. |