**A major part of the limbic system is the hypothalamus with its related structures.** They control: - Emotional behaviour - Internal conditions of the body such as temperature, osmolality of the body fluids, and drives to eat and drink, and to control body weight. These are collectively called **Vegetative Functions of the Brain**. **Functional Anatomy of the Limbic System: Key Position of the Hypothalamus** | ![[ETH/ETH - Systems Neuroscience/Images - ETH Systems Neuroscience/image111.png\|500]] | ![[ETH/ETH - Systems Neuroscience/Images - ETH Systems Neuroscience/image112.png\|600]] | |---|---| **Hypothalamus, a Major Control Headquarters for the Limbic System** ![[ETH/ETH - Systems Neuroscience/Images - ETH Systems Neuroscience/image113.png|500]] From this view of a cut of the Hypothalamus, the functions of specific regions can be appreciated. **Hypothalamus** represents less than 1% of the brain mass. It is one of the most important of the control pathways of the limbic system. It controls most of the **Vegetative and Endocrine Functions** of the body as well as many aspects of **Emotional Behaviour**. **Vegetative and Endocrine Control Functions of the Hypothalamus** - Cardiovascular Regulation - Regulation of Body Temperature - Regulation of Body water - Regulation of Uterine Contractility and of Milk Ejection from the Breasts - Gastrointestinal and Feeding Regulation - Stimulation of the lateral hypothalamic area results to extreme hunger, voracious appetite and intense desire for food. - Damage this area causes lose of desire for food, causing lethal starvation. **Hypothalamic Control of Endocrine Hormone Secretion by the Anterior Pituitary Gland**. **Behavioral Functions of the Hypothalamus and Associated Limbic Structures** **Effects Caused by Stimulation** - Stimulation of the lateral hypothalamus causes thirst and eating, increased general level of activity, leading to overt rage and fighting (strict connection with ANS). - Stimulation of the ventromedial nucleus causes sense of satiety, decreased eating and tranquility. - Stimulation of a thin zone of periventricular nuclei, leads to fear and punishment reactions. - Sexual drive can be stimulated from several areas of the hypothalamus especially the anterior and most of the posterior portions of the hypothalamus. **Effects Caused by Hypothalamic Lesions** Cause effects opposite to those caused by stimulation.