The Limbic System

Our Brain: The Limbic System

The term Limbic System is frequently used as though it referred to an anatomical structure, but it is really a theoretical concept about a group of structures that, many neuroscientists feel, are linked together in a functionally significant way. Because it is a theoretical concept rather than a concrete thing, different neuroscientists include different structures under the term “limbic system.” It is therefore a rather vaguely defined entity (the very usefulness of which some neuroscientists question).

However, more or less everyone includes the following structures in it. At its core is the hypothalamus. Around this core, and connected with it, the other limbic structures are arranged in a ringlike formation. Within the diencephalon, we include part of the thalamus (most theorists include the anterior and dorsomedial nuclei of the thalamus in the limbic system). Outside the diencephalon, in the temporal lobe, we include the amygdala and the hippocampus, together with a fiber pathway called the fornix, which courses under the corpus callosum as it links back to diencephalon, where it joins the hippocampus to a small nucleous but, rather, consists of a phylogenetically old kind of cortex, running along the inner surface of the temporal lobe. It is also strongly connected to the group of basal forebrain nuclei, including those embedded in the septum Several of these structures too are connected to the anterior cingulate gyrus, which is therefore also usually included in the limbic system.

This highly interconnected set of brain structures, most of which lie deep within the brain, comprises the limbic system. There are many other structures that connect with these in complicated ways, some of which are also sometimes considered “limbic.” Howere, these are not core components of the limbic system.

Limbic system is part of the basic anatomical material. The anatomical terms are mentioned time and again, and repeated exposure (especially in the context of discussion of their psychological functions) will lead to much greater familiarity with these terms and the anatomical structures to which they refer.

The Brain and the Inner World, Introduction to Basic Concepts. Mark Solms, Oliver Turnbull.

In the end, we believe, we shall be able to say with confidence: this is how the mind really works. Photo by Elena.