The limbic system is the innermost part of the brain, which is located below the thalamus. It comprises a complex set of brain structures. These brain structures are responsible for our emotional life. They are involved in many of our emotions including anger, fear, pleasure, happiness, and many more. Some structures of this system are even involved in memory.
Amygdala: It is an almond-shaped mass or structure in the brain. It comprises a set of neurons, which are involved in memory, emotional responses, and hormonal secretions. It is located deep in the medial temporal lobe of the brain, and is responsible for determining what memories are stored and where the memories are stored in the brain.
It is responsible for controlling the autonomic responses associated with fear. It is also involved in the emotions related to sex, like arousal. The abnormal functioning of amygdala could result in anxiety, autism, stress, and depression.
Hippocampus: Hippocampus is a curved part of the forebrain. It is located in the medial temporal lobe of the brain, and is involved in the formation of long-term memories.
It is responsible for sending memories to the appropriate part of the cerebral hemisphere for long-term storage and for their retrieval when essential. Any damage caused to hippocampus may result in the inability to build up new memories.
Thalamus: Thalamus, which is also referred to as the relay station, is a large, dual-lobed mass of gray matter cells. It receives auditory, somatosensory, and visual sensory signals, and relays them to the cerebral cortex.
It is responsible for regulating the motor functions. It connects the parts of the cerebral cortex involved in sensation and movement, with other parts of the brain, which are also involved in sensation and movement.
Hypothalamus: Hypothalamus is a small region (size of a pearl) of the brain, which is located just below the thalamus. It is responsible for regulating certain metabolic processes and autonomic functions.
It regulates sleep wake cycle, heart rate, hunger, thirst, and blood pressure. It is also important for regulating hormones, body temperature, adrenal, and pituitary glands. It is also involved in emotions such as anger, unhappiness, etc.
Cingulate Gyrus: It is a fold in the brain located in the medial part of the brain, between the cingulate sulcus and the sulcus of the corpus callosum. It is an integral part of the limbic system, which is responsible for coordinating the sensory inputs with emotions.
The frontal part of this area is responsible for associating memories to smells, sights, and pain. It is involved in the regulation of aggressive behavior and emotional responses to pain. It also regulates blood pressure and heart rate.
Olfactory Cortex: It is located within the medial temporal lobes, and is responsible for receiving sensory information from the olfactory bulb.
It is connected directly to amygdala and hippocampus, and is concerned mainly with the sense of smell. It is involved in the identification and awareness of odors.
Fornix: Fornix is a C-shaped bundle of fibers in the brain that connects hippocampus and hypothalamus. It is responsible for carrying the signals from hippocampus to the mammillary bodies and septal nuclei.
Thus, the limbic system is responsible for regulating various functions in the body including hormonal secretions, memory storage, motivations, motor functions, autonomic functions, emotional responses, and sensations.