Brain
There are dozens of other chemical neurotransmitters that are used in more limited areas of the brain, often areas dedicated to a particular function. Serotonin, for example—the primary target of antidepressant drugs and many dietary aids—comes exclusively from a small brainstem area called the raphe nuclei. Norepinephrine, which is involved in arousal, comes exclusively from a nearby small area called the locus coeruleus. Other neurotransmitters such as acetylcholine and dopamine have multiple sources in the brain, but are not as ubiquitously distributed as glutamate and GABA.
Brodmann area 10
The volume of the human BA10 is about 14 cm and constitutes roughly 1.2% of total brain volume. This is twice what would be expected in a hominoid with a human-sized brain. By comparison, the volume of BA10 in bonobos is about 2.8 cm, and makes up only 0.74% of its brain volume. In each hemisphere, area 10 contains an estimated 250 million neurons.