appsychologyunit.ppt

* * * * * * * The limbic system is a donut-shaped area in the center of the brain. This region is responsible for much of the influence on the body’s hormonal system (which in turn, controls much of our emotions such as fear and anger, as well as our basic motives for things like food and sex). There are four main parts to the limbic system – the hypothalamus (which controls the pituitary gland), the hippocampus, and the amygdala). The hypothalamus is about the size of a lump of sugar – in rats it is about the size of the head of a pin. The hypothalamus has three key functions: it is responsible for parts of our reproductive behavior, controlling our temperature, and our feeding behavior. It does this through its control of the pituitary gland, which monitors the secretion of hormones. Receiving certain types of sensory information triggers the hypothalamus to direct the pituitary gland to respond by secreting a particular hormone or to stop secreting a certain hormone. For example, you see a table laden with cookies, chocolate, and cake and your hypothalamus tells your pituitarty gland to secrete hormones that increases your hunger level. Similarly, the hypothalamus also influences reproductive behavior (destroying the hypothalamus ceases copulatory behavior in rats and dogs; stimulation of it will lead to increases in copulatory behavior). The hypothalamus also control your body’s internal temperature. In 1912, a researcher by the name of Barbour placed a silver wire into a dog’s hypothalamus. When the wire was heated, the dog’s body temperature decreased, when the wire was cooled, the dog’s body temperature increased. If damage, which is also called a lesion, is done to the hypothalamus, it can’t regulate increases or decreases temperature, but it can still influence shivering or vasoconstriction The hippocampus is the part of the brain that processes memory. If damage is done to this area, people are unable to create new memories. There is a ver