Hetherington & Ranson (1942) - damage to the hypothalamus in rats caused them to overeat and become grossly obese. Suggests that this area of the hypothalamus (ventromedial nucleus) was a satiety centre, (to inhibit feeding).
Anand and Brobeck (1951) - lesioned the lateral hypothalamus in rats, they completely stopped eating (alphagia). Suggests that the lateral hypothalamus was a feeding centre to stimulate feeding.
- Research is done on rats since humans rarely survive damage to the hypothalamus.
- Findings have to be extrapolated - lowers validity
The ventromedial nucleus and lateral hypothalamus = dual centre model of feeding. They respond to signals of hunger or food intake from the body.
- Supported by research where electrical stimulation of the two areas can stimulate or inhibit eating.
- Cannot act in isolation, they must receive information about the body's energy levels and food reserves.
Signals for starting eating
Social patterns - we eat at certain times
Smell and taste of food - stimulate release of enzymes for breakdown of food
Signals from stomach - ghrelin travels in the blood stream and signals degree of emptiness.
Cummings et al (2004) - measured ghrelin levels…