Motivation and Decision-Making Flashcards
Motivation
The internal state that causes an animal to behave in a certain way
Examples of biological motivations
*Thirst
*Hunger
*Mate-seeking
*Territorial Defence
Examples of Human motivations
*Biological
*Physiological
A change in responsiveness to a given stimulus may be due to…
*Maturation
*Learning
*fatigue
*Change in motivational state
Describe the homeostatic models of motivation?
To maintain homeostasis, a system requires a detection mechanism to note any deviation from an ideal value or set point ;
it must be able to mobilise the organism to make changes to return it to the ideal value, and it must also have some way to recognise when the desired change occurs and feed back to stop the mobilisation process.
Function of the Hypothalamus
- monitors changes in internal environment
-initates activity (both physiologcal and behavioural) to rectify imbalance
What is the hypothalamus connected to?
has connections to
*cerebral cortex
*Posterior parts of the brain
*Pituitary
It has a rich blood supply
What happens when thirsty?
*When depleted of water, body fluids are
hyperosmotic (saltier than normal), causing shrinkage of specialised neurons ( osmoreceptors ) in the lateral hypothalamus which causes increased rate of firing
*this activates neural circuits that cause
thirst and drinking behaviour
What are the physiological effects of thirst?
physiological effects: Release of antidiuretic
hormone (ADH) from posterior pituitary, stimulates kidney to retain water
Experimental evidence for key role of hypothalamus in thirst
*When a region of the lateral hypothalamus is electrically stimulated or has concentrated solutions introduced into it, goats respond by drinking
* If the lateral hypothalamus of a rat is damaged it does
not drink even when severely dehydrated
Hunger
*a strong motivation to seek out and
ingest food
*the state experienced by an animal as
the satiety from a previous meal wanes
Satiety
*terminates feeding behaviour , even if
food is still available
“feeeding centre” of hypthalamus
Lateral hypothalamus
“Satiety centre” of hypothalamus
ventromedial nucleus
Describe evidence of hunger/satiety
–Damage to the
ventromedial nucleus (VMN; satiety centre “)
causes rats to feed excessively
–electrical stimulation of VMN depresses feeding
–Damage to or stimulation of an area of the lateral hypothalamus
feeding centre “) has the reverse effects
Leptin
produced by adipose tissue, suppresses appetite
PYY (peptide YY)
secreted by small intestine
after meals, suppresses appetite
insulin
rise in blood sugar causes
pancreas to secrete insulin
- physiological role, also
acts on the brain to
suppress feeding
ghrelin
secreted by stomach wall, triggers feelings of hunger
Explain mice with mutant ob gene
Mice with mutant ob gene eat voraciously and grow much larger than normal
ob gene codes for leptin
How is the stomach involved in the control of feeding?
e.g. Stomach fullness inhibits feeding.
Blowfly larva: Distension of gut signals satiety,
CNS inhibits feeding reflex
What is food intake influenced by?
*Smell, taste, texture of food
*Amount of food available
*Stress, anxiety, depression, boredom
*Social custom, habit
What do fMRI studies associate obesity with?
*increased motivational drive to eat
*increased reward responses to food cues
*impaired food related self control processes
Hormones affect motivation. Which behaviours are affected by hormones?
especially reproductive behaviours
-territorialism
-aggression
-courtship
-parenting
Hormones?
*chemical substances produced by endocrine glands including the gonads and the pituitary
*travel in the blood to their target tissues
*present at low levels Glands
How do hormones influence reproductive behaviour?
Hormones influence reproductive behaviour by
–presence in the mature animal
–effects on the brain of the developing animal
What are the behavioural effects in the mature animal?
Effects on effector organs
effects on sensory receptors
effects on CNS
Effects on effector organs
(structures involved in the performance of behaviour) e.g testosterone stimulates development of nuptial pad in male Xenopus toads allowing the toad to grasp female efficiently
Effects on sensory receptors
e.g oestrogen stimulates the development of a brood patch in canaries, involving loss of ventral feathers and increased sensitivity to tactile stimuli; this increases the effectiveness of stimuli associated with the nest and thus affects behaviour during nest building and incubation.
Effects on the central nervous system
The main effect of circulating hormones on behaviour is by affecting the central nervous system directly.
Oestrogen affets act’s behaviour and reproductive tract
Testosterone
Implicated in courtship and aggressive behaviour of males
What is the evidence of testosterone
Evidence for this includes:
– Measured blood levels of testosterone are high during the
breeding season of seasonally breeding animals
- Castrated male doves show reduced aggression and courtship
Testosterone implanted in the anterior hypothalamus and preoptic nuclei of castrated doves stimulated this behaviour.
Progesterone
implanted in the same regions of the hypothalamus
*suppressed courtship and aggression
* stimulated incubation behaviour
Prolactin
secreted by the pituitary gland has various effects, usually on parental behaviour including the secretion of crop milk in pigeons.
Arginine Vasopressin (AVP)
affects social behaviour in prairie voles
Oxytocin
affects maternal behaviour in rats, and is implicated in prosocial behaviours
Physiologial effects of adrenalin
increases
–blood glucose
–blood pressure
–breathing rate
–metabolic rate
Behavioural Effects of Adrenalin
May enhance fear/aggression of animal directly or through
feedback
Coritsol
“stress hormone”
Physiological effects (peripheral) of oxytocin
*Uterine contractions
*Milk let-down
Behavioural effects (within brain) of oxytocin
*Parental behaviours
*Altruistic and prosocial behaviours
Phermones
*Chemical signals act between members of the same species
*Produced within one animal and released to environment
*Signal social status, sexual readiness, food trails, alarm
*Primer pheromones have long term effects e.g. influence
puberty, oestrus cycle
Name the messenger hormones
FSH - Follicle stimulating hormone
LH - luetinising hormone
Function of messenger hormones
Secretion of oestrogens and androgens (testosterone) by the gonads is regulated by the pituitary gland through messenger hormones
What controls the pituitary
hypothalamus
What can occur to the mammalian reproductive tract at an early stage
Has capacity to become either male or female
Y chromosome
Y chromosome carries sry gene which codes for tdr
(testis determining factor )
Testes produce testosterone “masculinising” brain
What happens to male rats deprived of testoterone at critical period?
*behaviour is demasculinized
*cannot be restored by large doses of testosterone
What happens to female rate given a tiny pulse of testosterone at crital period?
*behaviour is masculinized mount and thrust on receptive females
*lack oestrus cycle and hence are sterile
What was discovered about female mice developed between two brothers?
Female mice that developed between two
brothers have higher testosterone and are
more aggressive as adults
What do mehcanims of decision making include
*Inhibition of all but one response
*Reciprocal inhibition
What is an emotion?
*a multicomponent response
–physiological
–behavioural
–cognitive
–subjective
*to a stimulus or event that is typically
of importance to the individual
*is always
valenced (positive/negative)
What do emotions encourage animal to do?
*approach potential opportunities
*escape
from potential threats
Amygdala
*Monitor sensory inputs
*Search for threats
Prefrontal cortex
–uses information from amygdala in assessing and
responding to threats
–Moderates response to threat
-Integration of emotion
and decision making
-Damage results in
behavioural changes
including inappropriate
decision making
