neural mechanism ESSAY

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Neural Mechanism

THE DCM

The dual centre model suggests, Neural Mechanics associated with the control of eating are found in the hypothalamus.The are two important eating control centres found in the hypothalamus; the lateral and ventromedical hypothalamus, and they work cooperatively to control weight and food consumption.

the lateral hypothalamus is usually associated with hunger and through research its also been found to be a 'on switch' for eating behaviour, for instance hunger and cravings. stimulation of the lateral hypothalamus starts eating behaviour. the ventromedical hypothalamus is the opposite this signals to 'stop eating', this inhibits eating behaviour. (also known as the satiety centre)

low glucose levels in the blood activates the lateral hypothalamus, this stimulates a sense of hunger, causing the individual to search for food and eat food , therefore increasing glucose levels. the rise of glucose levels activates the ventromedical hypothalamus, theres a feeling of satiation, which inhibits further feeding.

Research evidence which supports the DCM comes from Anand et al, who found damaging the Lateral hypothalamus in rats led to a loss of appetite, lack of interest in food and weight loss. This is also shown in Hetherington et al who showed damaged to the ventromedical hypothalamus led to an animal overeating until they became obese. This shows clear evidence for the two brain areas of the feeding and satiety centre.

However this research is non human which shows this research lacks face validity as human characteristics can't be matched with animal research. for instance a human can barely survive with a damaged, this raises an issue of over generalising from animals to humans. Despite humans having similar mamolstic features such as the brain design, it can't be assumed that what happens in humans complex brain is similar to what occurs in a rats. there's a SUBTLE difference in the control of feeding between humans and animals.

This also raises the ethical issue of whether its right to change an animal's brain function for human research, as the animals rarely survive LESION and STIMULATION studies.

the dual centre model can be criticised on its deterministic explanation, which suggests that eating behaviour is controlled by internal mechanism, such as the lateral hypothalamus being the trigger for hunger.this suggests that people can't control their eating behaviours, however due to free will people can over ride their physical drive to eat due to factors such as a desire to be thin, or as a religious practice of fasting, this shows neural mechanisms don;t always control our eating behaviours.

preferences for sweet foods.

the evolutionary explanation suggests the preference for sweet foods would be adaptive for two factors.Sweet things contain high calories, so a sweet taste would, act as a READILY-DETECTABLE SIGNAL of nutrients , providing a source of energy.

Secondly compared to bitter/ sour things sweet thing were less likely to be poisonous, a sweet taste indicated safety..

In evolutionary terms those with a preference for sweet taste would be more likely to pass on their genes - and a genetic coding for a preference for sweetness to the next generation, this supports the widespread fondness for sweet food throughout the animal kingdom.