week 10 chris dodds Flashcards
What were the findings of Bechara et al (1994) study? Looking into the role of the orbitofrontal cortex in cognitive control?
controls: avoided risky decks + chose decks that would give them profit
lesions to occipital, temporal and dorsolateral cortex = equivalent performance
patients with OFC lesions: preference for riskier decks
In terms of the skin conductance response (SCR):
- during reward and punishment: similar SCR in reward and punishment for controls
- anticipatory SCR’s has reduced for patients with OFC lesions
What does the skin conductance response measure?
Measures sweating
What role does the orbitofrontal cortex play in value-based decision making?
activates a signal which serve as a value marker for a distinction between making choices with good and bad future outcomes
What is meant by the somatic Marker Hypothesis (Damasio)
-emotional info is needed to guide decision making
somatic markers= bodily reactions to emotional stimuli
OFC supports learning of making association between somatic markers + complex situations
OFC can use this info to predict behavioural choice outcomes
What does the study by Fellows et al (2003) suggest in terms of the OFC’s function?
- OFC is not just involved with stimulus-reward contingencies, but rather play a role in unlearning established associations
OFS lesion: had difficulty to pick up the reward switch in the serial reversal task
Give the findings of the study by Fellows et al (2003) looking into the role of OFC in reversal learning
patients with DLPFR - unimpaired
patients with OFC lesion- could learn initial respopnse contingencies (e.g. card A predicts reward, card B predicts punishment) however had difficulties learning contingency when reward/punishment were switched.
Give a study which supports the study by Fellows et al (2003) (role of OFC in reversal learning) and why it supports that study?
O’Doherty et al. (2001) - also looked at serial reversal learning
found specific regions of OFC responding preferably to rewards and punishment
medial OFC - stronger response to reward
Lateral OFC - stronger response during punishment phase
Different regions of OFC respond to the serial reversal task
Give a weakness of the OFC reversal learning hypothesis
Monkeys with OFC lesions do not show deficit in the serial reversal task
In comparison to humans, monkeys with OFC lesions do now show deficits in the serial reversal-learning task- why is this the case?
The study by Chudasama et al (2007) required monkeys to overcome an innate preference for larger food rewards - therefore, involves food rather than a standard serial learning task
Why is OFC viewed as an ‘accountant?’
Because it converts information about the outcome into a common neural currency
A lot of research emphasises the OFC playing a role in value based decision making, however the OFC plays role in more complex decisions such as regret. What evidence is there for this?
Normal control patients showed counterfactual thinking- higher satisfaction when win and when they realised they would have won less on alternative wheel. show lower satisfaction if would have won more on alternative wheel
OFC lesion - do not show counterfactual thinking. don’t vary their satisfaction based on if they would have won less or more on alternative wheel
Give three steps associated with the dopaminergic synapse
1) L-DOPA
2) Dopamine degradation
3) Dopamine receptors
Where is dopamine produced?
Produced by dopaminergic neurons in the ventral tegmental area (VTA) and substantia nigra (SN) in the midbrain
describe the two dopamine receptors
D1 receptor: more abundant in prefrontal cortex
D2 receptor: more abundant striatum
What is the role of dopamine in addiction?
- ## DA function is enhanced by acting on midbrain neurons. This increases extracellular concentration of DA
