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Limbic System





Brain| Information

  Name Limbic system
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  Image Brain_limbicsystemjpg
  Caption The limbic system within the Brain
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  Artery
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  BrainInfoType ancil
  BrainInfoNumber 247
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The limbic system ( involved in Emotion , motivation, and emotional association with Memory . The limbic system influences the formation of memory by integrating emotional states with stored memories of physical sensations. (see Emotional Memory ).


ANATOMY

The limbic system includes many different Cortical and subcortical Brain structures that differ depending upon which book is referenced. For ease of interpretation, this is a list of all the regions generally considered to be part of the limbic system:



FUNCTION

The limbic system operates by influencing the Endocrine System and the Autonomic Nervous System .
The limbic system is highly interconnected with a structure known as the Nucleus Accumbens , commonly called the brain's Pleasure Center . The nucleus accumbens plays a role in Sexual Arousal and the "high" derived from certain Recreational Drugs . These responses are heavily modulated by Dopamine rgic projections from the limbic system. In 1954, Olds and Milner found that Rat s with metal electrodes implanted into their nucleus accumbens would repeatedly press a lever activating this region, and would do so in preference to eating and drinking, eventually dying of exhaustion.Olds, J., Milner, P. 1954. Positive reinforcement produced by electrical stimulation of septal area and other regions of rat brain. ''J.Comp. Physiolo. Psycholo.'' 47, 419- 427

The limbic system is also tightly connected to the Prefrontal Cortex . Some scientists contend that this connection is related to the pleasure obtained from solving problems. To cure severe emotional disorders, this connection was sometimes surgically severed, a procedure of Psychosurgery , called a Prefrontal Lobotomy (this is actually a misnomer). Patients who underwent this procedure often became passive and lacked all motivation.

There is circumstantial evidence that the limbic system also provides a custodial function for the maintenance of a healthy Conscious state of mind.


EVOLUTION


The limbic system is embryologically an older part of the brain. It developed to manage 'fight' or 'flight' chemicals and is an evolutionary necessity for reptiles as well as homosapiens.

Recent studies of the limbic system of Tetrapods have made data available that challenge some of the long-held tenets of forebrain evolution. The common ancestors of reptiles and mammals had a well-developed limbic system in which the basic subdivisions and connections of the amygdalar nuclei were established.1


HISTORY

The French physician to include additional structures in a more dispersed "limbic system," more on the lines of the system described above.Maclean, PD. Some psychiatric implications of physiological studies on frontotemporal portion of limbic system (visceral brain). ''Electroencephalogr Clin Neurophysiol'' 1952;4(4):407-18. PMID 12998590 The concept of the limbic system has since been further expanded and developed by Nauta, Heimer and others.


BIBLIOGRAPHY

  • Damasio, Antonio. The Feeling of What Happens. San Diego: Harcourt Brace, 1999.

  • Damasio, Antonio. Descartes' Error. City: Penguin (Non-Classics), 2005.

  • Lautin, Andrew. The Limbic Brain. Kluwer, 2001.



REFERENCES