Limbic system

The limbic system is a group of brain structures that are involved in various emotions such as aggression, fear, pleasure and also in the formation of memory. The limbic system affects the endocrine system and the autonomic nervous system. It consists of several subcortical structures located around the thalamus:

Related Topics:
Brain - Emotion - Aggression - Fear - Pleasure - Memory - Endocrine system - Autonomic nervous system - Subcortical - Thalamus

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• hippocampus: involved in the formation of long-term memory
• amygdala: involved in aggression and fear
• cingulate gyrus (the circular shape of the cingulate gyrus resembles that of a "limb", hence the name)
• fornicate gyrus
• archicortex
• hypothalamus: controls the autonomic nervous system and regulates blood pressure, heart rate, hunger, thirst, sexual arousal and the sleep/wake cycle. Connected to the pituitary gland and thus regulates the endocrine system. (Not all authors regard the hypothalamus as part of limbic system.)

The limbic system is among the oldest parts of the brain in evolutionary terms: it can be found in fish, amphibians, reptiles and mammals.

Related Topics:
Fish - Amphibians - Reptile - Mammal

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The limbic system is highly interconnected with the brain's so-called pleasure center, a structure known as the nucleus accumbens. The nucleus accumbens is involved in sexual arousal and in the "high" derived from certain recreational drugs. These responses are heavily modulated by dopaminergic projections from the limbic system. Rats with metal electrodes implanted into their nucleus accumbens will repeatedly press a lever which activates this region, and will do so in preference over food and water, eventually dying from exhaustion.

Related Topics:
Nucleus accumbens - Sexual arousal - Drug - Dopaminergic - Rat

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The limbic system is tightly connected to the prefrontal cortex. It has been conjectured 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. Patients who underwent this procedure often became passive and lacked all motivation.

Related Topics:
Prefrontal cortex - Psychosurgery

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