The Limbic System

Limbic System Definition

The limbic system is an intricate and important part of the brain, as it regulates learning, memories, and emotions. More specifically, the limbic system is in charge of our most instinctual survival behaviors such as fight-or-flight response, feeding, and reproduction. You can think of the limbic system as a mixture of our higher thinking and functioning and our primitive emotions.

We have it in common with other animals such as other mammals, fish, and reptiles. It contains important areas of the brain, like the hippocampus and the amygdala. Where in the brain is it located? Let's take a deeper look.

The human brain, pixabay.com

If you were to open the brain, you would find the limbic system within the cerebrum, underneath the temporal lobes and the cerebral cortex.

Structure and Parts of the Limbic System

The limbic system houses several major areas that are significant to certain functions of the brain.

Limbic Lobe

This is the first major lobe area of the limbic system. It has three gyri.

• Cingulate Gyrus - The cingulate gyrus regulates our conscious functions, and our automatic functions such as an increase in heart rate when we are afraid; as an example, when we choose to run in the face of danger.

• Parahippocampal Gyrus - This area helps us navigate our way around, or find a specific location.

• Dentate Gyrus - The dentate gyrus is a large and important component of the limbic system; more specifically, the hippocampal region. It is in charge of creating episodic memories as well as memories of new environments. The dentate gyrus has three significant layers; the molecular layer, granule cell layer, and polymorphic layer. The prime directive or objective for this portion of the brain is to act as a communicator to the hippocampus to deliver information.

Amygdala

This almond-shaped area of the brain is located near the hippocampus and has a left and right side. It is in charge of our emotional responses like fear or pleasure. An interesting concept within the amygdala is the impression of emotions on memory. The amygdala can attach emotions to a memory, allowing it to be better remembered.

An example could be a special birthday party you had as a child, or, on the flip side, being afraid when the neighborhood dog chases you home.

Birthday party, pixabay.com

Hippocampus

The area of the limbic system called the Hippocampus means "seahorse" in Greek, and is shaped much like the creature itself. The hippocampus is in charge of our memories. It is a pairing between the two parts of the brain, or hemispheres. We can think of the hippocampus as a packaging warehouse for our memories. In this warehouse, the packages or our episodic memories are readied for long-term storage in other parts of the cerebral cortex. These memories are associated with sensations; this too takes place in the hippocampus. An example would be how the smell of fresh laundry perhaps reminds you of a family member. Another important factor that lives within the hippocampus is the spatial orientation that helps us navigate as we move around.

Hypothalamus and Thalamus

At the center of the limbic system lies the hypothalamus. It is in charge of our feelings of hunger, sexual arousal, regulation of body temperature and sleep cycles, and the release of hormones. Oxytocin, or the love hormone, is released in the hypothalamus.

Lesions of the hypothalamus influence unconscious functions and some motivated behaviors like combativeness and hunger. The lateral parts are involved with pleasure and rage. Lastly, the medial part is linked to aversions and displeasures.

The thalamus is in charge of our perception and all of our motor functions. The sensation of touching something soft, smelling something sweet, or seeing something frightening, is a message to the thalamus.

Damages to the Limbic System

Because the limbic system is a powerhouse of information processing for our nervous system, any damage can be detrimental. The most common medical conditions for those with damage within the limbic system are:

• Schizophrenia

• Epilepsy

• Autistic spectrum disorders