Neural Mechanisms in Controlling Eating Behaviour
Outline and evaluate the role of neural mechanisms in controlling eating behaviour (24 marks)
Today there is enormous interest in the psychological factors that can affects a person’s eating habits, but some of the clearest research findings have come from research into the brain (neural) mechanisms controlling eating behaviour.
One important mechanism to consider is the role of homeostasis in all mammals. Homeostasis is how the body maintains a constant internal environment. Our diet is essential to homeostasis as it provides the nutrients that allow physiological processes to be regulated within narrow limits. The body has evolved two separate systems – one for turning eating ‘on’ and one for turning eating ‘off’. Glucose levels are important in producing feelings of hunger – the less glucose present, the greater the hunger. Our lateral hypothalamus is activated when there is a decline in glucose levels, leading to feelings of hunger. A neurotransmitter found in the hypothalamus, called neuropeptide Y (NPY) is particularly important in turning on eating. Wickens found that if NPY was injected into the hypothalamus of rats, NPY would cause them to immediately begin feeding, even when satiated. This shows how a brain neurotransmitter is capable of controlling eating behaviour by causing an individual to begin feeding.
However, there has been doubt on whether the role of NPY is to influence feeding behaviour. Marie et.al genetically manipulated mice so that they did not make NPY and they found that there was no subsequent decrease in their feeding behaviour. Researchers suggest that the hunger stimulated by injection of NPY may actually be an experimental artefact. A NPY flood into the bloodstream could cause behaviours other than the behaviour caused by normal amounts of the neurotransmitter, showing that NPY may not be the key to controlling our eating behaviour. Nonetheless, it has been show in the real world that obese individuals become obese due to the
Today there is enormous interest in the psychological factors that can affects a person’s eating habits, but some of the clearest research findings have come from research into the brain (neural) mechanisms controlling eating behaviour.
One important mechanism to consider is the role of homeostasis in all mammals. Homeostasis is how the body maintains a constant internal environment. Our diet is essential to homeostasis as it provides the nutrients that allow physiological processes to be regulated within narrow limits. The body has evolved two separate systems – one for turning eating ‘on’ and one for turning eating ‘off’. Glucose levels are important in producing feelings of hunger – the less glucose present, the greater the hunger. Our lateral hypothalamus is activated when there is a decline in glucose levels, leading to feelings of hunger. A neurotransmitter found in the hypothalamus, called neuropeptide Y (NPY) is particularly important in turning on eating. Wickens found that if NPY was injected into the hypothalamus of rats, NPY would cause them to immediately begin feeding, even when satiated. This shows how a brain neurotransmitter is capable of controlling eating behaviour by causing an individual to begin feeding.
However, there has been doubt on whether the role of NPY is to influence feeding behaviour. Marie et.al genetically manipulated mice so that they did not make NPY and they found that there was no subsequent decrease in their feeding behaviour. Researchers suggest that the hunger stimulated by injection of NPY may actually be an experimental artefact. A NPY flood into the bloodstream could cause behaviours other than the behaviour caused by normal amounts of the neurotransmitter, showing that NPY may not be the key to controlling our eating behaviour. Nonetheless, it has been show in the real world that obese individuals become obese due to the