Motivation Flashcards
How has the biology of motivation been studied?
Although psychologists such as Maslow and McClelland have produced models of human motivational states, the biology of motivation has been systematically studied only in animals.
What are homeostatic or primary physiological drives?
Because of their roles in homeostasis (the maintenance of a constant internal environment), hunger and thirst are referred to as examples of homeostatic or primary physiological drives.
How are patterns of feeding behaviour determined?
Patterns of feeding behaviours are not determined simply by tissue deficiencies, psychological factors are also important.
On what has work with animals concentrated?
Work with animals has concentrated on body weight regulation and caloric intake of fats and carbohydrates, although diets are much more varied than this.
What is involved in the regulation of short-term meals?
A number of peripheral factors are involved in the short-term regulation of meal size. These include sensory aspects of food, the presence of food in mouth and stomach, the hormone CCK released from the upper intestine, and glucose receptors in the walks of blood vessels.
Where are central mechanisms of feeding regulation found?
Central mechanisms of feeding regulation are found in the hypothalamus. Lesions to the ventro-medial nucleus produce over-eating and obesity in rats, whereas lesions to the lateral hypothalamus eliminate feeding.
What is the glucostatic hypothesis?
Glucose is the most important fuel for the body, and the glucostatic hypothesis suggests that some aspects of glucose metabolism is the key to food intake and body weight regulation.
What is the lipostatic hypothesis?
The lipostatic hypothesis is an alternative model (to the glucostatic hypothesis) and emphasises the role of fat storage cells, the adipocytes, which determine the body-weight set point.
The lipostatic and the glucostatic hypotheses seem both too simple to account for the complexities of feeding behaviour and digestion.
What causes human obesity?
The VMH-lesioned obese rat is not highly motivated to eat, and is also extremely irritable. Although attempts have been made to draw parallels with human obesity, it is clear that human obesity has no such single cause. Inherited, physiological, and psychological factors are all involved.
What is anorexia nervosa?
Anorexia nervosa is a severe reduction in food intake most often found in young girls, who may lose up to 70% of their body weight. Psychological factors may be especially significant. There is no obvious physiological cause, and it seems that psychodynamic approaches may be more effective at explaining and treating the disorder.
What is osmotic thirst?
Drinking is directed to maintaining the dynamic balance between intracellular and extracellular water compartments. Osmotic thirst occurs when water is lost through sweating, evaporation, and via the kidneys, increasing the osmotic pressure of the extracellular compartment. Osmoreceptors in the hypothalamus sense the changes, drinking is stimulated and the hormone ADH release from the pituitary to promote the recovery of water from the kidney tubules.
What is hypovolemic thirst?
Hypovolemic thirst occurs with a drastic reduction in extracellular water, perhaps due to a cut or internal haemorrhage. Besides drinking and ADH release, renin is secreted by the kidneys, which eventually results in raises blood levels of angiotensin; this constricts blood vessels and helps raise blood pressure.
Which neurotransmitters affect drinking and feeding behaviour?
Drinking behaviour is linked to acetylcholine neurotransmitter pathways in the brain. Feeding is influenced by pathways using noradrenaline and serotonin. Drugs affecting these neurotransmitters have significant effects both on feeding and drinking.
Rats will press a bar to receive electrical stimulation in certain parts of the brain. This rewarding ESB is more potent than any natural reinforcer, in that it does not satiate. What is the relationship between ESB and natural behaviour?
We do not know the relationship, if any, between ESB and natural behaviour, although the brain circuits supporting ESB may be involved in motivated behaviours such as curiosity and exploration which have no obvious reinforcer.
