Week 3-Motivation and Eating Flashcards
Major Motivation Theories
Instinct theories- Behaviour is motivated by instinct which is innate and activated by environmental stimuli. Early theory- INSTICT-AUTOMATIC; innate
Maslow’s Hierarchy of needs-When different motives compete, basic survival needs to be satisfied first before motivated to satisfy higher level needs (self-esteem)
Arousal theory-Behaviour motivated by the need to achieve optimum levels of arousal
Drive-reduction theory- Motivation orginates from biological needs to maintain the body in the state of BALNACE/EQUILLIBRIUM
Incentive theory- Behaviour motivated by internal (intrinsic) and external (extrinsic) incentives or rewards.
Drive Reduction Theory(Hull, 1951)
Physiological needs—–> create drives—–> to behave in a certain way. Want to satisfy this need and reduce drive.
Homeostasis-maintenance of steady internal state.
When we drift away from homeostasis- creastes drive and motivation to satisfy drive in order to maintain homeostasis. Survival dependent to maintain internal states.
Optimal arousal theory
The aim of motivation is to maintain an optimum level of arousal (state of alertness; mental or physical activation).
Raise (socialise or exercise) or lower (read a book/ take a bath)arousal levels.
- Individual differences in optimal arousal levels(some people need a lot more stimulation than others to maintain optimal levels)
- Levels of arousal can influence performance
What happened in Hetherington & Ranson (1940) study when lateral hypothalumus was removed from rats?
Stellar (1954)Role of ventromedial hypothalamus?
Caused reduced appetite for food
Electrical stimulation caused rat to start eating even though already fed- lateral hypothalamus hunger center in the brain.
Damage to different part causes animals to overeat and become obese-ventromedial hypothalamus responsible for STOPPING EATING-SATIETY CENTRE(satisfied eaten to satisfy)
Stellar’s study-Dual centre model for feeding ( balance of activity between lateral and ventromedial hypothalamus to eat or stop eating)
What happened in Hetherington & Ranson (1940) study when lateral hypothalumus was removed from rats?
Stellar (1954)Role of ventromedial hypothalamus?
Caused reduced appetite for food
Electrical stimulation caused rat to start eating even though already fed- lateral hypothalamus hunger center in the brain.
Damage to different part causes animals to overeat and become obese-ventromedial hypothalamus responsible for STOPPING EATING-SATIETY CENTRE(satisfied eaten to satisfy)
Stellar’s study-Dual centre model for feeding ( balance of activity between lateral and ventromedial hypothalamus to eat or stop eating)
What problems do DAMAGE to LATERAL HYPOTHALAMUS cause?
- Wide motor disturbances
- Lack of sensory input
- Damage fibres of passage for reward and sensory processing
Where is taste responded in?
Orbitofrontal cortex
Explain Positive incentive theory in relation to food
Positive-Incentive theory says that motivation to eat is driven by anticipated reward value of food and environmental factors.
Can explain many findings (e.g. conditioned feeding behaviours to environmental cues, sensory-specific satiety) better than drive reduction theory.
Dopamine reward system activated by food
Mesocortical dopamine projects to OrbitoFrontal Cortex (OFC)
OFC neurons respond to specific tastes; activity reduces when sensory-specific satiety occurs.
Eating Disorders- Anorexia Nervosa
What is Anorexia Nervosa?
Anorexia nervosa
- Persistent restriction of energy intake leading to significantly low body weight
- Intense fear of gaining weight, or persistent behaviour that interferes with weight gain
- Disturbance in experience of own body weight, lack of recognition of seriousness of current low body weight
Eating Disorders- Bulimia
What is Bulimia?
- Recurrent episodes of binge eating
- Eating more than most within a discrete time period
- A sense of lack of control over eating
- Compensatory behaviour to prevent weight gain – vomiting, laxatives, fasting, excessive exercise
Biological explanations of the causes of anorexia
Hypothalamus Dysfunction Theory
HYPOTHALAMUS IMPAIRED/ DISFUNCTIONAL IN ANOREXIA(no longer a regulator)
Garfinkel & Gardner (1982) -disturbed hypothalamic function means lack of weight thermostat
Other impaired hypothalamic functions (e.g. body temperature control) supports this
Body mass index (BMI) correlated with GM in the hypothalamus(shrinking in size)
But other regions also atrophied (loss of volume in other brain regions as well)
Dopamine
Some studies suggest the dopamine system might be hypersensitive in anorexia
Amphetamine (which activates dopamine system) leads to anxiety in anorexia nervosa but euphoria in healthy controls
Could explain why dopameine released by food produces anxiety (not pleasure) in anorexia
Biological explanations of the causes of bulimia
Binge eating, loss of control and eating despite fullness
In striatum and amygdala, brain activity to food not reduced when full vs hungry
Suggests disinhibited eating in BN could result from a failure to devalue food reward when full up
