Figure 2.6 | The Central Core Brain Structures | The central core of the brain includes (a) the brain stem (which includes the medulla and the pons), the thalamus attached to the top of the brain stem, and the reticular formation that passes through both; (b) the cerebellum, which extends from the back of the brain stem; and (c) the basal ganglia that surround the thalamus. The hippocampus and amygdala are limbic system structures.