How we change what others think, feel, believe and do

Midbrain

The midbrain, or mesencephalon is made up of two main structures and surrounds the cerebral aqueduct.

Tectum

The tectum is in the dorsal part of the midbrain.

The superior colliculi are a part of the visual system and are involved in visual reflexes and reactions to moving stimuli.

The inferior colliculi appear as four bumps on the dorsal surface of the brain stem and are a part of the auditory system.

Tegmentum

The tegmentum sits beneath the tectum.

Reticular formation

The reticular formation ('little net') is a large and complex structure of over 90 nuclei that sits at the core of the brain stem.

It connects with the cerebral cortex, the thalamus and the spinal cord.

It is involved in sleep, arousal, attention, movement and various basic reflexes.

Periaqueductal grey matter

Periaqueductal grey matter is mostly cell bodies (hence 'grey matter'). It controls basic animal sequences of movement such as for fighting and mating.

Opiates that stimulate receptors in this region decrease pain sensation.

Red nucleus

The red nucleus is involved in motor coordination, particularly the shoulder and upper arm.

Substantia nigra (SN)

The substantia nigra ('black substance') is so called because of the higher levels of melanin in its dopaminergic neurons.

The pars compacta is mainly an input to the basal ganglia circuit, supplying the striatum with dopamine. The pars reticulata, is mainly an output, sending signals to many other brain structures

The substantia nigra plays an important role in eye movement, reward seeking, addiction and movement planning.

The nigrostriatal pathway originates in the substantia nigra.

Parkinson's disease is caused by the death of dopaminergic neurons in the pars compacta.

Ventral tegmental area (VTA)

The Ventral tegmental area, or ventral tegmentum, is a group of dopaminergic cells that are the origin of the mesolimbic dopamine pathway that is highly significant in reward and sensations of pleasure. It also includes GABA and glutamate neurons.

It is also connected with the amygdala and may be connected with fear and avoidance.