Limbic system

The limbic system, also known as the paleomammalian cortex, is a set of brain structures involved in emotional processing and motivation in humans and many other animals. In humans it is located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.

Its various components support a variety of functions including emotion, behavior, long-term memory, and olfaction.

The limbic system is involved in lower order emotional processing of input from sensory systems and consists of the amygdala, mammillary bodies, stria medullaris, central gray and dorsal and ventral nuclei of Gudden. This processed information is often relayed to a collection of structures from the telencephalon, diencephalon, and mesencephalon, including the prefrontal cortex, cingulate gyrus, limbic thalamus, hippocampus including the parahippocampal gyrus and subiculum, nucleus accumbens (limbic striatum), anterior hypothalamus, ventral tegmental area, midbrain raphe nuclei, habenular commissure, entorhinal cortex, and olfactory bulbs.

Structure

The limbic lobe was originally defined by the French anatomist Paul Broca in 1878, as a series of cortical structures surrounding the boundary between the cerebral hemispheres and the brainstem. The name "limbic" comes from the Latin word for the border, limbus. Further studies began to associate these areas with emotional and motivational processes and linked them to subcortical components that were then grouped into the limbic system.

In recent years, multiple additional limbic fiber connectivity has been revealed using diffusion-weighted MRI. The equivalent fiber connectivity of all these pathways has been documented by dissection studies in primates. Some of these fiber tracts include the amygdalofugal tract, amygdalothalamic tract, stria terminalis, dorsal thalamo-hypothalamic tract, cerebellohypothalamic tracts, and the parieto-occipito-hypothalamic tract.