Neural Mechanisms In Eating Flashcards
What did Wickens find about NPY?
When injected into the hypothalamus of rats, NPY causes them to immediately begin feeding, even when satieted. Repeated injections of NPY produces obesity in just a few days
What did Zhang discover about leptin and obesity?
OB/OB mice have defective genes for the protein leptin. Leptin is normally produced by fat tissue and secreted into the blood stream where it travels to the brain and other tissues, causing fat loss and decreased appetite. In OB/OB mice, this process does not happen. Injecting OB/OB mice with leptin causes them to lose weight dramatically
What did Marie find about NPY?
Genetically manipulated mice so they didn’t make NPY. They found no decrease in feeding behaviour. The researchers suggest that the hunger stimulated by injections of NPY may be an experimental artefact, in that the flood of NPY during experimental manipulation a could cause behaviour not like that caused by normal amounts of the neurotransmitter
What did Yang find about NPY?
Showed that NPY is also produced by abdominal fat not just the brain. They suggest that this leads to a vicious cycle where NPY produced in the brain leads to more eating and the production of more fat cells and so on. Yang believes we can target individuals at risk of increased levels of NPY and treat them with drugs that turn NPY off
What is the role of the lateral hypothalamus?
‘On’ switch for eating. Damage to it causes aphagia and stimulation of it elicits feeding
What is a problem with labelling the LH as the ‘on switch’ for eating?
Damage to the LH caused deficits in other aspects of behaviour rather than just hunger.
What is the role of the ventromedial hypothalamus?
Acts as an ‘off switch’ for eating. Damage caused overeating (hyperphagia) and stimulation inhibits feeding
What did Gold find about the VMH?
Lesions to the VMH alone did not result in hyperphagia and only produced overeating when they included other areas such as the para ventricular nucleus. However, subsequent research hasn’t replicated this finding.
What did Rolls and Rolls find about the amygdala?
Surgically removing the amygdala in rats would cause animals to consume both familiar and unfamiliar foods indiscriminately, whereas other rats would avoid unfamiliar foods and only eat the familiar ones. This shows that the amygdala has a role in the selection of foods based on previous experience
What does the inferior frontal cortex do?
Receives messages from the olfactory bulb. Because odours influence the taste of foods, damage to this is thought to decrease eating because of less sensory responses to food odour and taste
How can damage to the amygdala and inferior prefrontal cortex explain klüver-bucy syndrome?
Patients with this syndrome show increased appetite, indiscriminate eating, and attempts to eat non-food items. Research on the damage of these two brain areas suggest that food cues no longer accurately represent their real reward value to the individual
What did Zald and Pardo do to support the claim that the amygdala participates in the emotional processing of olfactory stimuli?
Exposed healthy adults to aversive olfactory stimuli while measuring blood flow to the amygdala by using a PET scan. Exposure to unpleasant odours produced blood flow increase to the amygdala whereas non-aversive odours did not cause increased blood flow.
What did Lutter say about stress and hunger?
The body produces extra quantities of the hormone ghrelin in response to stress. This is a natural response to stress as it reduces depressive and anxious behaviours in stressful situations. However, ghrelin also boosts appetite, leading to increased comfort eating
