Peribrachial area

Peribrachial area is the region around the brachium conjunctivum, located in the dorsolateral pons; contains acetylcholinergic neurons involved in the initiation of REM sleep.

Mechanism for PGO wave generation and propagation
The neurophysiological studies on PGO waves conclude that the generation of these waves reside in a collection of neurons located in the pons, regardless of species research is done on. From this point, the neurons branch out in a network that leads the phasic electrical signal toward the lateral geniculate nucleus and the occipital lobe.

Within this network, there are two types of neuronal groups: executive neurons and modulatory neurons.

Executive neurons
Executive neurons are the ones that help to generate and propagate the PGO waves throughout the brain. One research paper further breaks down this "class" of neurons into two subsets: triggering neurons and transfer neurons. All of these neurons are located in the peribrachial area, which is a group of neurons surrounding the superior cerebellar penduncle.

Triggering neurons
These neurons are located in the caudolateral region of the peribrachial area. These neurons actively fire during non-REM (NREM) sleep. The most recorded activity of the neurons is during the N3 stage of NREM, also known as the slow-wave sleep cycle. These same neurons are also active during REM sleep, but at a greatly reduced amplitude than NREM sleep.

Transfer neurons
The neuronal cells that allow for the transfer of PGO waves from the pons to the other parts of the brain reside on the rostral portion of the peribrachial area. This grouping of cells fire in precisely two modes. The first mode is burst firing through low-threshold Calcium (Ca2+) ion channels. The other mode is a repetitive tonic firing through Sodium (Na+) dependent ion channels.