Module 2: Drug habits, cognitive control and neural basis Flashcards
Distinguish between goal-directed action and habit based on their definitions [paraphrasing and analyzing] Explain how habits are formed according to the 'Law of Effect' [paraphrasing], and explain the ideal conditions for forming a strong habit [evaluating] Explain how to experimentally test whether a behavior is goal-directed or habitual [paraphrasing], and identify the essential features of this experimental paradigm [analyzing] Apply the 'outcome devaluation' paradigm to a new research quest
When is drug-seeking called goal-directed?
When it is based on an expectation (cognitive criterion) and consists of a positive hyper-evaluation (motivational criterion) of the drug
What does the habit account argue that drug-seeking involves?
Behaviour is followed by a reward or absence of a negative event which reinforces the SR association. If stimulus is presented, old behaviour can be triggered and can become dominant after many repetitions.
Outcome-devaluation test
- Instrumental learning so if a rat presses lever they will gain pellets in the Skinnerbox
- Outcome devaluation so given unlimited food
- Critical test phase: if goal-directed then they will reduce lever pressing due to reduced value, but if it is a habit then will continue to press the lever
Why is this test carried out in extinction?
A devalued outcome will lead to weaker S-R associations and if not due to extinction unclear why the rat presses less for the reward. If behaviour is immediately adjusted then suggests it is goal-directed
Habit theory of addiction
There is a transition from targeted control to drug habits. There are individual differences in forming dominant habits and some can be more vulnerable in developing an addiction. Drugs are strong reinforcers of S-R habits and drugs lead to structural changes in the brain which results in a stronger tendency to rely on control.
Dual process models
Substance abuse is the result of reinforced automatic/reflexive bottom-up processes and weakened top-down cognitive/executive functions. This means that impaired cognitive control can result in relying on habits
What does previous research suggest about habits?
- habits allow for responses to be efficiently executed to free up cognitive resources
- prefrontal cortex and dorsomedial striatum involved in goal-directed action and dorsolateral striatum supports habit-based behaviour
- specific neural circuity for outcome insensitive habitual behaviour unclear
Aims of this research
To determine whether instrumental responding in humans can be habitual (whether response will persist no matter the outcome) and to uncover neural mechanisms which contribute to development and control habitual behaviour in humans
Method of this research
Participants were given little training or were over-trained to press a button with a rewarding outcome delivered on a variable- interval schedule. Responses were self-paced and an image was shown and a schematic indicating a button to press. Then either a picture or grey circle was shown to indicate a reward. Then devaluation took place in selective satiation, where participants had to eat the food until no longer pleasant. Then the responses were assessed and fMRI measurements took place.
Results found from the study
Response rates for the 1 day group decreased during presentation of the cue to the devalue cue in comparison to the day 3 group even though there was no difference for valued outcome. Activity in DLS increased during the final sessions and left nucleus accumbens displayed a significant response to reward presentation for both groups. Ventromedial prefrontal cortex showed a significant effect in anticipation of the upcoming rewards.
What do these results mean?
Posterior putamen into globus pallidus became more sensitive to stimuli associated with a behavioural response. Significant difference between first and last 2 sessions so area becomes more involved after successive days of training. Goal-directed to habitual control is a dynamic relationship and early phase of habit learning occurs when behaviour is goal-directed. Reward expectancy is important in goal-directed behaviour. vmPFC and DLS play a role in behaviour, but DLS can preferentially influence behaviour. Goal directed representations remain intact throughout.
Goal-directed actions
These are instrumental behaviour that are performed with a certain goal and that a certain behaviour will increase the likelihood of reaching that goal. Belief criterion argues that goal-directed actions are mediated by knowledge of action-outcome relationship. Desire criterion is that these actions are only executed when outcome is desirable. Habits occur irrespective of the evaluation of outcome.
Factors which can influence habits
- behavioural intentions are weak predictors of actions performed frequently than those performed rarely
- habits are contextually dependent (habit discontinuity hypothesis)
- goal pursuit and behavioural repetition are intertwined
How has goal-directed action been studied in humans?
- selective satiation
- ‘instructed devaluation’ which participants are explicitly informed that an outcome is devalued as it does not earn points or credits
- but, symbolic outcomes can fail to engage basic learning mechanisms
Fabulous Fruit game
Participants press keys to gain fruit icons to gain points which are each worth points. Some of the fruits were then told they were worth less points and healthy participants were able to do well in this task in a goal-directed manner