Instrumental conditioning

Question 1

Thorndike

Answer 1

If in the presence of a stimulus a response is followed by a satisfying state of affairs, the connection between the stimulus and the response will be strengthened. If the response if followed by an annoying state of affairs, the connection between the stimulus and response will be weakened

Question 2

Goal directed actions

Answer 2

Stimulus –> response –> outcome decisions

Question 3

Habitual actions

Answer 3

stimulus –> response associations

Question 4

Outcome devaluation

Answer 4

can demonstrate that SR and SOR both contribute to instrumental conditioning

Question 5

Adams and Dickinson 1981

Answer 5

Devaluation of sucrose (lever 1) leads to pressing of lever 2 (pellets) after limited training (SOR learning) but after extended training there is no devaluation effect and both levers are pressed evenly

Question 6

Clinical relevance of outcome devaluation

Answer 6

OCD – patients show an insensitivity to outcome devaluation (Gillan et al., 2011)
Stress results in less sensitivity to outcome devaluation (Schwabe & Wolf, 2011)
Actions learnt under the influence of alcohol are less sensitive to outcome devaluation (Hogarth et al., 2012, Biological Psychology)
Alcohol seeking behaviour becomes insensitive to devaluation if over-trainined (Corbitt et al., Biological Psychiatry, 2012)

Question 7

Likely candidate for instrumental conditioning?

Answer 7

Striatum (caudate putamen and nucleus accumbens). It receives information from a variety of cortical and subcortical areas and then sends information back to the motor cortex.

Question 8

Yin et al 2005

Answer 8

Lesions of the dorsomedial striatum in rats impairs sensitivity to outcome devaluation (i.e. lesioned rats behave in a habitual manner).

Question 9

Basolateral Amygdala

Answer 9

The Basolateral Amygdala is necessary
for the outcome representation. Balleine B W et al. 2003. Lesioned rats had far fewer actions at an extinction test for both devalued and valued stimuli

Question 10

Killcross & Coutureau 2003

Infralimbin vs Prelimbic

Answer 10

Damage to these two areas provides a double dissociation. When given limited training prelimbic FC lesions impair outcome devaluation, but infralimbic FC lesions are without effect. However, when given extended training infralimbic FC lesions fail to show a reduction in sensitivity to outcome devaluation; they remain goal-directed when sham rats display habitual behavior. Prelimbic FC lesions continue to show habitual responding when overtrained.
The double dissociation between prelimbic and infralimbic regions of the FC the outcome devaluation task demonstrates that S-R and S-O-R learning occurs independently of one another.

Question 11

Prelimbic

Answer 11

Damage after acquisition of the behaviour does not impair outcome devaluation suggesting that the prelimbic region is important for encoding associations, but its not where the memory is stored (Ostlund & Balleine, 2005). Prelimbic necessary for acquiring SOR association but not necessary once this behaviour is acquired

Question 12

Infralimbic

Answer 12

Inactivation after overtraining results in habitual behaviour becoming goal-directed again. Therefore, the infralimbic region is not important for learning S-R associations, but for suppressing the influence of S-O-R associations on behaviour (Coutureau & Killcross, 2003). The fact that infralimbic FC lesions stops rats from displaying habitual responding suggests that it may be necessary acquiring S-R associations. This is not the case. If the infralimbic region is inactivated once habitual responding has been acquired, the rats return to showing goal-directed behavior. The infralimbic region is not necessary for acquiring S-R learning, but is necessary for suppressing the influence of S-O-R associations on behavior.

See slides for diagram

Question 13

Olds 1958

Answer 13

Electrical stimulation to the ventral tegmental area (VTA) leads to the release of a neurotransmitter called dopamine. In rats, electrical stimulation to the VTA appears to be rewarding. Rats will show a preference for spatial locations in which the stimulation occurred, and moreover, they learn to press a lever for stimulation.

Question 14

Mobbs et al 2003

Answer 14

Humour, a pleasurable emotion, activates the nucleus accumbens, an area that receives dopaminergic input from VTA leads to strong evidence that dopamine is the brain’s pleasure chemical.

Question 15

Anhedonia hypothesis

Answer 15

Pimozide treated rats stop responding for food reward. Wise 1982 - the food stopped tasting good, lost its pleasure. But maybe not. Parkinson’s patients rate foods as being as pleasant as do healthy subject (Travers et al. 1993)

Question 16

Berridge and Robinson 1998

Answer 16

Incentive salience. dopamine is necessary for ‘wanting’ but not ‘liking’ of rewards. E.g. Rats with dopamine depletion will eat flavoursome foods as much as normal rats, but will they will not work for the food (Salamone et al. 2002)

Question 17

Kiyatkin, 2002

Answer 17

The dopamine response is a maximal at the time point for the lever press rather at the time point of receiving heroin.

Question 18

Schultz et al. 1997

Answer 18

Studies in monkeys have shown that dopamine also appears to be important for predicting reward. If a reward is predicted by a particular cue then the dopamine signal occurs when the cue is presented, but not when the reward occurs. The dopamine signal appears to be driven by ‘prediction error’: the difference between what was expected to occur and what did occur.

Question 19

Recorla - Wagner model

Answer 19

animal learns from discrepancy between what they expect to happen and what actually happens

Question 20

Kamin Blocking effect

Answer 20

The association between the CS and US is blocked if during the conditioning process the CS is presented together with a second CS that has already been associated with the unconditioned stimulus. Rescorla wagner model explains this The model says, essentially, that if one CS already fully predicts that the US will come, nothing will be learned about a second CS that accompanies the first CS. dopamine comes to signal how well reinforcement is predicted