Neural Mechanisms Involved In Controlling Eating Behaviour

Question 1

Neural means..

Answer 1

‘relating to the nervous system’

Question 2

Neural mechanisms

Answer 2

-They control eating behaviour regions in the brain and neurotransmitters; similar to homeostasis- regulating the body

Question 3

Feeding centre

Answer 3

Lateral Hypothalamus

Question 4

Satiety centre

Answer 4

Ventromedial hypothalamus

Question 5

How are glucose levels relevant to controlling eating?

Answer 5

-The glucose levels in the blood indicate to the body that we need to eat. For example, high glucose blood levels activates satiety and low glucose activates the lateral hypothalamus

Question 6

What is ‘ghrelin’ and its relevance in controlling eating?

Answer 6

-This is a hormone secreted fro the stomach, the amount released is directly proportional to the ‘emptiness’ of the stomach. This then stimulates feeding.

Question 7

What is CCK and it’s relevance in controlling eating?

Answer 7

-CCK (Cholecystokinin) appears to have the opposite effect to ghrelin. Studies have shown that increasing CCK in animals and humans reduce meal size. There is good evidence that CCK signals satiety to the brain and controls meal size.

Question 8

Satiety signals

Answer 8

• Increase glucose
• Decrease ghrelin
• Increase CCK

Question 9

Hunger signals

Answer 9

• Decrease glucose
• Increase ghrelin
• Decrease CCK

Question 10

Which cells store fat?

Answer 10

Adipocytes, fatty tissue is made up of these cells

Question 11

What is leptin and how is it relevant to neural mechanisms?

Answer 11

-Leptin is a hormone released from fatty tissue. It acts as an indicator of body weight to hypothalamic mechanisms controlling long term food intake.

Question 12

Hetherington and Ranson

Answer 12

• They demonstrated that lesions of an area of the hypothalamus of the brain cause rats to overeat and become dramatically obese.
• The obese rat had a lesion to the ventromedial hypothalamus (VMH)

Question 13

Anand and Brobeck

Answer 13

-Found that a lesion in the lateral hypothalamus led to a loss of feeding behaviour in rats known as aphagia

Question 14

Cycle of feeding involving the hypothalamus

Answer 14

• > Feelings of hunger
• > Signals of food intake (rise in blood glucose, decrease ghrelin)
• > VMH satiety centre activated
• > Satiety feelings of fullness, feeding stops
• > Signals of declining nutrient levels (decrease in blood glucose, increase ghrelin)
• > Lateral hypothalamus feeding centre activated

Question 15

Evaluation for neural mechanisms

Answer 15

Hetherington & Ranson - support that damaging the ventromedial hypothalamus leads to more eating
Anand & Brobeck - support that damaging the Lateral hypothalamus leads to a loss of feeding.

Question 16

Methodological evaluation for neural mechanisms

Answer 16

• Weakness is that rates have different brains structure to humans so its not valid to generalise to humans
• Weakness is that the rats were deliberately damaged, whereas the patient for example was damaged by the accident and so you cant be sure that the entire VMH was damaged - it could’ve effected other areas of the brain
• Strength is that its a lab experiment so highly controlled and because a certain area was targeted and a clear result was found so good causal relationship
• While the size is different the basic structure of the mammalian brain is very similar across different species, so the role played by the hypothalamus should be very similar.

Question 17

Carlson

Answer 17

-They found that the obese mice have missing gene that produces leptin as this hormone acts as a satiety signal and so without it they don’t have the feeling of being full.

Question 18

Carlson Oversimplification

Answer 18

-However in reality while there are some rare individuals who are overweight because of this leptin deficiency, but majoritively overweight people have normal or even higher levels of leptin. Therefore it seems that the brain mechanisms are insensitive to leptin.

Question 19

Other factors

Answer 19

-Other than biological factors, social and cognitive factors are just as effecting, as a lot of people will conform to the social norms and psychological factors can also overwhelm biological food choices if you’re trying to be healthy.

Question 20

Cognitive factor

Answer 20

• We’re hungry but we resist eating because we’ve decided to diet
• or we conform to social norms like being polite

Question 21

Biological factor

Answer 21

-Therefore need to supplement natural mechanism with ideas from other approaches for full understanding

Question 22

Schachter et al

Answer 22

-To illustrate this point further, schachter et al conducted an experiement measuring the amount of crackers eaten when the real time was manipulated by a faster or slower clock. Obese people ate more when the clock falsely showed it was closer to dinner time (classically conditioned to eat)

Question 23

Becker (anorexia)

Answer 23

-Anorexia increased when TV introduced Fiji, suggesting the importance of the effect on eating behaviour from the media.

Question 24

Practical applications

Answer 24

-Obtaining detailed evidence about the neural mechanisms controlling hunger and satiation might lead to beneficial treatment for those with eating disorders such as AN or obesity - potential development for medical interventionm

Question 25

Neural description

Answer 25

-Neural mechanisms are involved in control regions of the brain in order to regulate eating behaviour. The hypothalamus gland is involved in homeostasis in our bodies which controls water levels and food intake and for this reason it is believed to be a major factor in shaping our eating bahviour