Lecture 4 - Learning & Motivation Flashcards
1
Q
Basic Drives
A
- homeostasis
- behavioural adaptation to meet bio needs
- the role of learning in anticipating biological needs
2
Q
homeostasis
A
- body strives to maintain a constant environ (weight, temp, chemicals)
- when bdoy is challenged by loss oss of regulated variable there is an effect on motivation that changes behaviour to challenge this state
- in action:
> weight & metabolism (keesey & corbett 1984) - restriction of food leads to reduction in metabolic rate which limits extent of weight loss
> brain system & hunger - dif regions of hypothalamus have dif roles in feeding. lesions to ventromedial hyp = overeating. lesions of lateral hypothalamus = weight loss - schepers & Bouton 2017: learning is also important. learn that lever = food then in extinction phase animals are hungry and lever does not need to food. at test if behaviours are driven solely by bio needs animal would press lever more but rats pressed it more when stated than when hungry = not just motivational state drives behaviour. in this case it is context dependent behaviour
3
Q
how motivational states affect behaviour (Hull)
A
- Hull’s theory of learning & motivation
> drive - motivational state activated by bio need (homeo)
> reinforcers - things that satisfy a need reduce drive
> habit - learning. how much has been learned about the reinforcer meeting that need - behavioural strength = drive x habit
- if either drive or habit are 0 there would be no behaviour.
- Bolles (1975) review of lever pressing in rats. some animals more hungry than others. behaviour harder to enxtinguish the more the behaviour had previously been reinforced (habit learning) and greater the state of deprivations (drive)
- Balleine 1992: if not hungry during training do they learn in the same way?
> inc drive did not lead to inc behavioural strength (in group that was trained when full)
> we also need to learn the reinforcer acc satisfy needs - drive and habit not sufficient to describe adaptive behaviour. need to learn reinforcer is good.
- is behaviour motivated by desire to anticipate or avoid need?
4
Q
anticipating need (fitzsimons & le magnen 1969)
A
- rats given a high protein diet need to drink alot
- when rats on low protein diet were switched to high protein diet they initially drank a lot after meals
- eventually they inc water intake before meals
- drinking was done in anticipation to thirst
5
Q
optimising time and effort (collier & johnson 1997)
A
- our behaviour is also optimised by time and effort
- as effort to obtain food inc meal sizes go up but frequency dec. overall intake consistent
- behaviour is structured in anticipation of needs and reduction of expenditure of effort
6
Q
how does anticipation occur
A
- Birch 1991 - looked at snack eating in children
- room associated with food (A) showed potentiated eating
> the children ate quicker in room A as they had learned to eat in room A. longer in room B.
> showed potentiated eating in environ associated with food
> cues in environ become signals/associations to eat
7
Q
cue potentiated feeding
A
- cues associated with food lead to overeating when sated (full)
- learning can lead to eating even when drive is 0
- Johnson (2013) even when animals are full you get potentiated feeding effect
8
Q
cue potentiated motivation for food
A
- pavlovian to instrumental transfer
- corbitt & Balleine (2012)
1. stage 1 - pavlovian
> dif auditory cues paired with dif outcomes
> passively learned sound lead to food
2. instrumental
> dif actions paired with the same dif outcomes
> more active outcomes
3. PIT - put them in chamber and combine these things
> can press levers trained in stage 2 & cues from stage 1 played to see how effects behaviour - doing a behaviour to get a response will be heightened if another cue is telling you there is food available (PIT)
- playing same sound to a lever get a specific PIT effect which enhances behaviour
- can enhance behaviours by having cues around to signal rewards
- get a general inc in lever pressing when cues are associated with food
- cues associated with outcome can also drive behaviour
9
Q
acquired motivations
A
- signals and rewards motivate behaviour (& drives)
- rewards can have emotional effect that impact behaviur too e.g. contrast effect
10
Q
negative contrast (flaherty 1991)
A
- if you are shifted to something less good it is going to feel worse than someone who have never experienced the good thing
- rats shifted from 32% sucrose to 4% solution drink less than rats with only access to 4%
- previous experience made 4% taste less good = less drinking
11
Q
licks and lick clusters
A
- can measure bouts between lick clusters and no. licks
- higher sucrose the more the animal will drink but only up to a certain point. at about 10% (8% peak) no. licks peak and then drops (too sweet)
- lick clister size palatability is a measure of how much they like it and is linear inc
- can measure intake (motivation) and cluster size (likeability)
- Austen & sanderson (2016
> similar procedure, varied context a and b on darkness and pre-exposure to 4% or 32% sucrose. also played sound or not.
> neg contrast in context B with 32% where conc reduced. mice drank it like it was less palatable
12
Q
incentive motivation (kenneth space)
A
- drive - motivational state driven by need
- habit - extent of learning
- K - incentive motivation (motivating effect of reward) driven by experience
- behavioural strength = drive x habit x K
- if any = 0 there will be no behaviour
- Birch (1991) - during test drive was low but in room A incentive motivation high as learned value of snacks = high behaviour overall
- neg contrast effect reduced incentive motivation. rats hungry (high drive) but incentive motivation low = overall low motivation
- conc:
> need to maintain homeostasis changes motivatational states which change behaviour
> changes in behaviour are also in anticipation of needs
> anticipatory behaviours reflect learning os signals of reward and incentive value of rewards
13
Q
the neural basis of reinforcement
A
- Olds (1958) - rats implanted with electrodes in hypothalamus or VT area
- pressing lever = stimulation.
- preferred lever pressing over food.
why?
14
Q
dopamine and reward
A
- VTA is key area for dopamine release
- striatum is reward hub integrating reward system and outputting info to motor cortex of motivated behaviour
- Nacc linked to reward value
- VTA stim = dop release = activity in dop neurons in nacc = integrates with signals from other parts of brain = outputs info back to motor cortex = drive behaviour
15
Q
The role of Nacc & reward (humour)
A
- Mobbs et al 2003 - funny cartoons led to higher BOLD activation in Nacc
- Wise et al (1978) - rats trained to give lever press for food (stage 1), in test stage some rats continued to receive lever > food training but now given pimozide a dop receptor antagonist impairs dopamine
> control group presses lever throughout (rewarding)
> dop antagonist group drop performance like they are not being rewarded = food stop being rewarding - why?
> anhedonia hypothesis - food stopped tasting good & dopamine may be pleasure chemical
16
Q
dopamine and liking
A
- parkinsons damages dopamine neurons in basal ganglia. do these people report less liking?
- Sienkiewicz-Jarosz et al (2013) - tested preference for sweet flavours in parkinsons patients
- parkinsons did not differ signif from controls. have prior experiences?
- can also look at liking behaviour non verbally e.g. hedonic (licking lips, paw grooming) and aversive (open mouth)
- Berridge & Robinson (1998) - rats lesioned dopaminergic neurons vis drug 6-OHDA & given sucrose.
> dop depletion did not reduce hedonic reactions to sweet sucrose
> no evidence dopamine depletion reduces liking
17
Q
is dopamine the brains pleasure chemical - no.
A
- incentive salience hypothesis - dopamine needed for wanting not liking
- rats with dopamine depletion will eat flavoursome foods as much as normal but will not work for the food = dopamine plays role in obtaining reward
- lever pressing for heroin (Kiyatkin 2002) - dop response is max at rime point for lever press rather than when receiving heroin = reflect wanting
18
Q
response to recreational drugs
A
- pimozide (dop receptor antagonist) fails to reduce high from amphetamine but reduces cravings &brauer & de wit 1996/7)
- inc dopamine can inc cravings but not affect the high from cocaine (hanley et al 1998)
- shows important in motivation
19
Q
liking
A
- what is necessary for liking?
- endogenous opiods may have similar effects to opiates e.g. morphine which inc pos response to pleasurable stimuli and reduce neg response to aversive (rideout & parker 1996)
20
Q
addiction
A
- has wanting disconnected from liking?
- incentive salience hypothesis proposes wanting & liking are separate processes that although sometimes work in tandem can function independent
- in addiction has massive wanting especially as it progresses while liking is stable or reduces
- these processes often work together but have dif neural mechanisms and can be disconnected
21
Q
dopamine and error prediction
A
- Schultz et al 1997
- giving juice with no prediction shows dopamine neurons activated. then train light + juice and over time dop activity shifts to cue that predicts reward. dopamine inc with cue
- dop signal initally happens to reward but transfers to predictive cue and eventually reacts to the cue not reward
- in extinction see reduction of activity in dop neurons
- matches rescorla wagner model (1972) - how much we learn is dictated by what happens to us vs what we expected to happen. has positive increment in learning if something good happens when not expected to. can also be neg increment.
- dopamine may be predictor signalling when something happens that we do not expect
22
Q
kamin blocking effect
A
- learning X is blocked if a reward is already expected by something else
- waelti et al (2001) - when expect reward we get dop activity, when we don’t expect we get less.
- dopamine reflects how much an outcome is predicted
0 if outcome changes and remove expected outcome get a drop in activity or if inc beyond expectation get an inc in activity
