The forebrain controls body temperature, reproductive functions, eating, sleeping, and the display of emotions.

At the five-vesicle stage, the forebrain separates into the diencephalon (thalamus, hypothalamus, subthalamus, and epithalamus) and the telencephalon which develops into the cerebrum.

The cerebrum consists of the cerebral cortex, underlying white matter, and the basal ganglia.

In humans, by 5 weeks in utero it is visible as a single portion toward the front of the fetus.

When the embryonic forebrain fails to divide the brain into two lobes, it results in a condition known as holoprosencephaly.