Module 2: Drug habits, cognitive control and neural basis

Question 1

When is drug-seeking called goal-directed?

Answer 1

When it is based on an expectation (cognitive criterion) and consists of a positive hyper-evaluation (motivational criterion) of the drug

Question 2

What does the habit account argue that drug-seeking involves?

Answer 2

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.

Question 3

Outcome-devaluation test

Answer 3

1. Instrumental learning so if a rat presses lever they will gain pellets in the Skinnerbox
2. Outcome devaluation so given unlimited food
3. 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

Question 4

Why is this test carried out in extinction?

Answer 4

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

Question 5

Habit theory of addiction

Answer 5

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.

Question 6

Dual process models

Answer 6

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

Question 7

What does previous research suggest about habits?

Answer 7

• 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

Question 8

Aims of this research

Answer 8

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

Question 9

Method of this research

Answer 9

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.

Question 10

Results found from the study

Answer 10

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.

Question 11

What do these results mean?

Answer 11

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.

Question 12

Goal-directed actions

Answer 12

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.

Question 13

Factors which can influence habits

Answer 13

• 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

Question 14

How has goal-directed action been studied in humans?

Answer 14

• 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

Question 15

Fabulous Fruit game

Answer 15

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

Question 15

What has been found in animal lesion research?

Answer 15

• pre-training lesions of prelimbic cortex led to behavioural autonomy and important in learning process underlying goal-directed action
• lesions of dorsomedial striatum disrupt goal-directed performance
• lesions of dorsolateral striatum disrupt habit formation (can become goal-directed and sensitive to devaluation)
• infralimbic context important, can be part of corticostriatal pathway

Question 16

What has human neuroimaging research found?

Answer 16

-preferential responding for outcome was associated with ventromedial prefrontal cortex/medial orbitofrontal cortex
- those with strong connectivity with ventromedial prefrontal cortex and caudate act more goal-directed in slips-of-action test
- premotor cortex-posterior putamen connectivity was negatively related with performance
- posterior putamen was a predictor of habitual control

Question 17

Clinical relevance in addiction

Answer 17

Recreational drug use starts as voluntary but can lead to strong S-R associations and develops into compulsive drug-seeking habits. Shift towards behavioural autonomy is reflected in progression from ventral to dorsal striatum. Weak prefrontal functioning is a vulnerability factor

Question 18

Clinical relevance in OCD

Answer 18

OCD were impaired at directing responses towards valuable outcomes and away from devalued ones. Found that those with OCD continued to press to avoid the devalued shock, related to hyperactivity in ventromedial prefrontal-orbitofrontal cortex and caudate

Question 19

Clinical relevance in obesity and eating disorders

Answer 19

Excessive consumption of energy-dense food and lack of physical activity are important to rise in obesity. Obese and lean men were trained to obtain snacks and then devalued these. The reduction in response was negatively related to BMI. Rats on a binge-eating diet failed to adjust their performance

Question 20

How are habits found to be a transdiagnostic compulsive trait?

Answer 20

Overreliance on habit learning has been found in Parkinson’s disease, treatment response in SAD and schizophrenia, no habit propensity found in children with ASD. Unclear whether impaired sensitivity to outcome revaluation is related to general impairment in cognitive control (working memory and response inhibition). Stress could play a role in mediating observed deficits, can lead to dominant habitual control.

Question 21

Challenges for the field

Answer 21

• an integrative approach should be used to understand habits across approaches. Issues with ecological validity and integrating research into inflexibility of habits assessed with outcome revaluation and efficiency of trained behaviour. Look at how these aspects are interrelated
• habit interventions. Habits should try to turn desired behaviour into a habit, use of implementation intention to improve context-dependent habits, remove contextual cues associated with old habit and capitalise on existing habits to build more.