PsychSim 5
PsychSim 5: HUNGER AND THE FATRAT
Date: 1/27/15
This activity provides a simulated experiment on weight regulation in rats.
The Hypothalamus
• What are the two techniques used to study hypothalamic dysfunction? How do they differ? The two techniques used to study hypothalamic dysfunction are stimulation and destruction. To simulate the hypothalamus a small wire probe is inserted into the hypothalamus and a weak but constant current is passed through its insulated tip. Generally, simulation makes the controlling region perform its function until the current is stopped. Whereas destruction is performed with the same probe, but it is performed at a much higher current and it stops the region from performing its function by causing lesions on the affected area.
Experimental Simulation
• What conclusions were you able to draw about the effects of the following procedures on the experimental rats:
• Stimulation of the lateral hypothalamus (LH)?
Causes overeating
• Destruction of the LH?
Causes undereating
• Stimulation of the ventromedial hypothalamus (VMH)?
Causes undereating
• Destruction of the VMH?
Causes overeating
• What did you learn from this experiment about these two regions of the hypothalamus?
The LH is the “hunger center” and destroying it leads the rat to starve while stimulating it causes the rat to start eating. The VMH is the “satiety center” and destroying it causes the rat to eat large amounts of food and stimulating it causes the rat to not eat.
Some Cautions
• What are the two problems with a simple conclusion to this research question?
PsychSim 5: Hunger and the Fat Rat 53
1. The rat with VMH destruction did not keep on gaining weight indefinitely; instead, the rat appeared to level off after about 40 days at a new, higher but stable weight
2. Other research has found that similar disturbances in eating behavior can be produced by damage or stimulation to other regions of the rat’s brain.
Date: 1/27/15
This activity provides a simulated experiment on weight regulation in rats.
The Hypothalamus
• What are the two techniques used to study hypothalamic dysfunction? How do they differ? The two techniques used to study hypothalamic dysfunction are stimulation and destruction. To simulate the hypothalamus a small wire probe is inserted into the hypothalamus and a weak but constant current is passed through its insulated tip. Generally, simulation makes the controlling region perform its function until the current is stopped. Whereas destruction is performed with the same probe, but it is performed at a much higher current and it stops the region from performing its function by causing lesions on the affected area.
Experimental Simulation
• What conclusions were you able to draw about the effects of the following procedures on the experimental rats:
• Stimulation of the lateral hypothalamus (LH)?
Causes overeating
• Destruction of the LH?
Causes undereating
• Stimulation of the ventromedial hypothalamus (VMH)?
Causes undereating
• Destruction of the VMH?
Causes overeating
• What did you learn from this experiment about these two regions of the hypothalamus?
The LH is the “hunger center” and destroying it leads the rat to starve while stimulating it causes the rat to start eating. The VMH is the “satiety center” and destroying it causes the rat to eat large amounts of food and stimulating it causes the rat to not eat.
Some Cautions
• What are the two problems with a simple conclusion to this research question?
PsychSim 5: Hunger and the Fat Rat 53
1. The rat with VMH destruction did not keep on gaining weight indefinitely; instead, the rat appeared to level off after about 40 days at a new, higher but stable weight
2. Other research has found that similar disturbances in eating behavior can be produced by damage or stimulation to other regions of the rat’s brain.