The Limbic System
The limbic system is responsible for motivational and emotional behaviors. The two main structures of the limbic system are the amygdala and hippocampus.
The Amygdala
The amygdala is an almond-shaped structure that plays a significant role in emotional learning, behavior, and memories. The amygdala works closely with the hippocampus by relaying emotions (primarily fear, anger, and pleasure) and behaviors to the frontal lobe for analysis.
The Hippocampus
Our most vivid memories are emotional because there is a strong connection between the amygdala and the hippocampus. The hippocampus is critical for learning and memory and is one of the only brain areas that gain neurons throughout life. The conversion of short-term memories into lasting long-term memories is the hippocampus’s primary job.
The Diencephalon
The hypothalamus, pineal gland, and thalamus are the three primary structures of the diencephalon.
The hypothalamus
The hypothalamus controls the pituitary gland and most of the hormones that regulate homeostasis.
The Pineal Gland
The pineal gland works with the hypothalamus in regulating the circadian rhythm (sleep-wake cycle) via the release of the hormone melatonin.
The Thalamus
The thalamus is the cerebrum’s chief of staff. All sensory information, except most olfaction, passes through the thalamus before reaching the cerebral cortex. The thalamus filters sensory information, so only the most crucial information makes it to our consciousness. Therefore, most of the sensory information your sense organs collect, you will never perceive.
The Cerebellum
The cerebellum is a walnut-sized area of the brain that has the highest concentration of neurons. The cerebellum comprises only ten percent of the brain’s mass but houses more than half of the brain’s neurons. The cerebellum’s primary function is to coordinate motor movements, balance, and posture. Without a cerebellum, motor movements would be rough, large, and uncoordinated.
The Brain Stem
The brain stem comprises many structures, but you will focus on four: the corpus quadrigemina, reticular formation, pons, and medulla oblongata.
The Corpus Quadrigemina
The posterior region on the top of the brain stem houses four small, rounded nuclei called the corpus quadrigemina. The upper two nuclei are the superior colliculi, which are responsible for visual reflexes. Auditory reflexes are the production of the two lower nuclei called the inferior colliculi.
The Reticular Formation
The reticular formation is a long, thin cluster of gray matter that spans most of the posterior brain stem. Consciousness consists of arousal and awareness. Arousal is the on/off switch of awareness. The reticular formation is essential for arousal, and damage to it may lead to a coma.
The Pons
The pons is in the middle of the brain stem on the anterior side. The pons acts as a bridge between the cerebellar hemispheres and the cerebellum and cerebrum. It also plays a role in respiration.
The Medulla Oblongata
The medulla oblongata is at the base of the brain stem and connects to the spinal cord. The medulla oblongata is responsible for most of the body’s vital functions, such as heart rate, respiration, and blood pressure.