Category: 

What is the Limbic System?

The pineal gland is part of the limbic system.
Rats are commonly used in laboratory testing.
Article Details
Free Widgets for your Site/Blog
There has never been a documented human death associated with a tarantula bite.  more...

April 19 ,  1775 :  The American Revolution began.  more...

The limbic system, named after the Latin word limbus for edge, is the innermost part of the brain, wrapped around the core ventricles. It is filled with cerebrospinal fluid and various clumps of white matter, which does not play much of a role in cognition.

This system is called the "old mammalian system" or the "mammalian brain," in the popular triune brain model, which splits the brain into three parts depending on their location and functions. The other parts are the reptilian brain or the brain stem, and the cerebral cortex or the neocortex. These are responsible for "lower" and "higher" behavior respectively.

The limbic system's components are the amygdala, the hippocampus, the cingulate gyrus, fornicate gyrus, hypothalamus, mammillary body, epithalamus, nucleus accumbens (the brain's famed "pleasure center"), orbitofrontal cortex, parahippocampal gyrus, and the thalamus. Each plays an important role in making things run smoothly in the brain. Analogous structures can be found in almost all mammals such as dogs, cats, and mice, though not in reptiles, which only possess a brain stem.

Ad

The limbic system is the home of emotions, motivation, the regulation of memories, the interface between emotional states and memories of physical stimuli, physiological autonomic regulators, hormones, "fight or flight" responses, sexual arousal, circadian rhythms, and some decision systems. It is what gets "duped" when people get addicted to hard drugs. Because the addiction happens in the "lower," "preconscious" portion of the brain, we cannot rationally consider its effects, and therefore recovery and relapse avoidance can be difficult. Rats given switches connected to electrodes which electrically stimulate their nucleus accumbens will continue pressing the switch at the exclusion of all else, including food or sex.

On top of the limbic system is the cerebral cortex, the "thinking brain." The thalamus acts as a liaison between the two. The cortex evolved dependent on the limbic system, which was present before it. Every beneficial adaptation in the neocortex had to "play nice" and interoperate efficiently to justify its own retention through improving the overall fitness of the organism. The pineal gland, a famous part of the limbic system located in the epithalamus, is a rare example of a vestigal brain organ, which was much larger and differentiated in an earlier part of our evolutionary history.

Ad

Discuss this Article

anon150446
Post 5

Where did you get your info on Reptiles? Alligators have a limbic system. It is keenly tied into their sense of smell. It drives them to hunt for food and to defend territory. I suggest you watch Discovery Channel or Animal Planet a few more hours a day.

anon147780
Post 4

Take the Limbic System definition with more than a grain of salt. How could "does not play a role in cognition" be accurate when it contains the two of the most important brain structures for cognition - the hippocampus and the amygdala!

anon123082
Post 3

How could a gland that merely releases melatonin be "perhaps the most important organ in the brain"? Try any of the cerebral lobes. Try the more than half dozen hormonal producing hypothalamus, tryin the cerebellum for balance. .Anyone who thinks the pineal gland is the most important part of the brain is just wrong, ignorant of the immensely vital functions of the rest of the brain.

Babalaas
Post 2

@ Anon70770- You are right. At one point in history doctors thought the pineal gland was a vestigial remnant from our species evolution. Now the medical community accepts the fact that the pineal gland's limbic system function is to produce and regulate melatonin, regulate the onset of puberty, and regulate our metabolism.

The pineal gland does begin to calcify as we grow older and loses some of its functionality. If I had to guess, this would have been the reason that scientists thought the pineal gland was a vestigial part of the brain.

anon70770
Post 1

The pineal gland is far from being vestigial. It is well functioning and perhaps the most important organ in the brain. You should update your research.

Post your comments

Post Anonymously

Login

username
password
forgot password?

Register

username
password
confirm
email