Examples of damage to PFC
Phineas Gage
Before the accident he had been their most capable and efficient foreman, one with a well-balanced mind, and who was looked on as a shrewd smart business man.
He was now fitful, irreverent, and grossly profane, showing little deference for his fellows. He was also impatient and obstinate, yet capricious and vacillating, unable to settle on any of the plans he devised for future action. His friends said he was “No longer Gage.
Elliot (Wallis, 2007)
Elliott excelled in college and rose rapidly through the ranks of a building firm.
People described him as a role model and a natural leader.
Age of 35 doctors diagnosed Elliot with a brain tumour.
The operation to remove the tumour was successful, but the surgery left Elliot with bilateral damage to his OFC.
Neuropsychological tests could find no evidence of brain damage.
Tests of his intelligence, memory, reading and writing comprehension, verbal fluency, visuospatial abilities, and facial recognition revealed average to superior performance.
He could talk intelligently and knowledgeably about current issues.
Even tests designed specifically to tax frontal lobe processes, such as working memory, role switching, and cognitive estimation, failed to reveal any deficits.
So was Elliot unaffected by the damage?
♣ Within months of the operation, he had quit his job,
♣ Lost a large sum of money to a scam artist,
♣ Divorced his wife,
♣ Lost contact with family and friends
♣ Remarried a prostitute he had known for a month: ended in divorce six months later, and he moved in with his parents.
In short, prior to his tumour Elliot had made a series of excellent life decisions, but within months of the operation he made a series of catastrophic ones.
Even simple decisions were difficult because he would agonise over every possible consideration. Some decisions are not even thought about, choosing a seat. A computer would “think” about every pro and con of every possibility, if we did this it would take too long.
Damage to PFC leads to behaviours
Rage
• Raine et al., (1998) PET studies show reduced glucose metabolism in the OFC of individuals with violent and antisocial history
o Damage to OfC caused rage in Phineas gage
o OFC modulates behaviour – Stops rage
Utilization Behaviour
Patient responses seem overly ‘stimulus driven’ and ignore social conventions
Lhermitte (1983)
For the patients, the presentation of objects implies the order to grasp and use them.
The inhibitory function of the frontal lobes is suppressed.
Stimulus-Reward Learning and Flexible Behaviour - Perseveration and Disinhibition
Roll, 1996
o One of the earliest deficits associated with OFC lesions in monkeys was a failure to perform stimulus-reward reversals
o A monkey learns that choosing one of two objects will lead to a reward.
o Then the contingencies reverse and the monkey must learn that to get a reward he now has to choose the previously unrewarded object.
o Monkeys with lesions of OFC were impaired at the task.
o Following the reversal, they were unable to inhibit responding to the previously rewarded object, a behaviour called perseveration.
o Later studies revealed that the deficit was specific to OFC damage.
- This same deficit that underlies the inability to reverse stimulus-reward associations might also underlie the patient’s poor decisions.
- One possibility is that the patient is unable to modify his/her behavior in response to negative feedback.
- For example, scam artists might initially work to gain our trust, but we realize their intentions before we are taken advantage of and modify our behavior accordingly.
- In contrast, Elliott may have been unable to modify his initial trust and so was swindled by the fraudster.
- Patients with OFC damage have no issues with learning a task, but have difficulty when the task is reversed. They find it difficult to change their behaviour. This difficulty has been correlated with socially irresponsible or disinhibited behavior (Rolls et al., 1994, 1998)
Gambling task
Iowa gambling task (Bechara et al, 1997):
Four decks of cards, and the subject must choose from these decks one card at a time.
• Each card wins the subject a small amount of money, but some of the choices also lose money. The aim of the game is to win as much money as possible.
• Unbeknownst to the subject, two of the decks are risky: They are associated with large gains but also large and frequent losses.
• In the long term, choosing from these decks is a losing strategy.
• Control subjects initially favour the decks associated with the largest gains but, after encountering losses, gradually realise that this choice will lose them money, and they alter their choices accordingly.
• Patients with OFC damage likewise initially favour the decks associated with larger gains, but unlike control subjects, they continue to favour these decks until they have lost all their money.
Roll’s explanation
One possibility is that the patient is unable to modify his/her behavior in response to negative feedback.
Somatic Markers Hypothesis
Damasio (1994)developed a theory of how autonomic responses might facilitate decision-making called thesomatic marker hypothesis.
Bodily states corresponding to the emotions produced while evaluating different courses of action (so called somatic markers) help to facilitate normal decision-making.
The role of OFC is to store associations between patterns of environmental inputs and the somatic states that those inputs produce.
In effect, the patient loses the ability to make a decision by gut feeling
Purely rational appraisal is oftennot possible because we don’t have accessto all the required data, somatic markers provide useful heuristics for dealing with situations where ‘knowledge’ is missing.
Explains the Iowa Gambling task
o Lack of anticipatory response is not due to failure to associate rewards with action, but due to the Lack of emotional response affecting decision making
o They do not generate somatic markers needed to complete the task - Emotional response in normal subject’s guides decision making before rational argument can be formulated.
o Fellows & Farah, 2005 – Task may be challenging for OFC damage because it requires them to change their initial perceptions and behavior.
Emotions are needed to make choices
Emotions are needed for decision making
Elliot lost the connection between the OFC and “primitive” brain areas that generate emotions. OFC integrates visceral emotions into decision-making
• When you are drawn to a certain entree on the menu, or a particular romantic prospect, the mind is trying to tell you that you should choose that option. Gut feeling!
• A brain that can’t feel can’t make up its mind
Sensory, effective and motivational information are all integrated in the OFC, in working memory, to derive the value of the potential outcomes, you need to value one thing over the other
Gut instinct that helps us to choose” But what happens when you have too much choice?
• Schwartz, 2002
o “What if I had chosen the other..”
o Cant make a decision because we can’t ponder everything
o The more choice the more regret
o Maximisers aim to maximize his or her outcomes, Seven samples revealed negative correlations between maximization and happiness, optimism, self-esteem, and life satisfaction, and positive correlations between maximization and depression, perfectionism, and regret.
What are emotions?
Emotions are mechanisms to set goals and establish priorities
• Emotions are multicomponent responses to challenges or opportunities that are important to the individual’s goals particularly social ones
• What ever the goal and the source of the situation, is the MEANING that gives rise to emotion
Differentiate emotions from moods, sensations, personality and disorders (Ekman):
Brief: between 1 and 5 seconds, anything longer is a mood.
Cross species: phenomena that we should see in other mammals, rudimentary in nervous system and should see rudiment in other species.
Emotions are coherent: facial, behaviour, physiology expression work together.
Involve automatic unconscious very fast appraisal of stimuli.
Have quick onset.
Disagreements about emotions
Is emotion discrete or continuous?
Is emotion an “atom” or “molecule”?
Is emotion an antecedent or consequent of cognition?
Evolutionary approach to emotions (Selfish gene book)
Central ideas in evolutionary perspectives
Emotions are genetically coded biologically processed that are wired into our nervous system
The number of avaliable emotions are constrained by biology, there are only a certain number of facia muscles
Emotions are closed systems - like reflexes
Emotions are evolutionary adaptations to selection pressures. Advantageous traits are selected for and make it to the next generation
Natural - Fear of heights, spiders, snakes.
Sexual
Group pressures - Organism who are better able to get along with the group have greater chances to reproduce. Cooperative wolves more likely to reproduce. To be an effective group member.
The environment and the problems faced when we evolved (EEA) has affected how we behave now.
Research relies on sources of data that require a lot of inference
Study close primates (branched away 7 million years ago),
Archaeological records (musical instruments, how skeletons evolved, how we died)
Look at hunter and gatherers society now (most closely resemble pre-industrial societies)
- Emotions are designed to solve problems, they are functional. We would know the function of emotions by understanding their elicitors.
♣ a) Reliable elicitors of emotions
♣ b) Systematic consequences - Universality. If we see universality, we can infer that something has evolved – emotions are present in other animals = Adaptation/Evolutionary
- Cross species comparisons tell us that human emotions are different - language, representation, ability to reflect self-consciousness
- Social adaptation: Societies want the father to be engaged and devote resources to their offspring. When you go see a baby you tend to say the baby looks like the father – Reinforcement that the father is the father, as we are certain the mother is the mother
Emotions are adaptations, they have functions
- Prioritisation: emotions enable rapid orientation to events in the environment – threat or opportunity
- Organisation: emotions coordinate responses – fight, flight can’t be made consciously as it would take too long – emotional response
Social constructionism or constructivism
Emotions are constructed within a particular culture, historical moment through language and values.
- Differences between emotions do not reside in low level physiological processes - same process
Happy nuns
o Nuns wrote an autobiography since youth, the ones who expressed more positive emotions in their autobiographies lived significantly longer – in some cases 10 years longer – than those expressing fewer positive emotions.
Some of their brains have the neurochemistry of Alzheimer, they have the physiology of the syndrome but culturally they have created no evidence of Alzheimer.
o That’s the point of constructivism - Emotions are open systems: Pieces of emotion can be put together in any number of ways
o Facial expression, physiological processes, vocalisation and touch patterns, skeletal movement can be arranged by culture into any configuration - Culture and emotions shape each other in bidirectional fashion.
Emotions shape our culture and culture shapes what we think.
Emotions are social rules – If you are in love you act like you are in love
Research
Compare cultures - Values like the culture of honour show how this variance shape the nature of emotions
Inuits don’t get angry even when the only form of transport is stolen
Ethnography - Live in the culture.
Cathy Lutz living with the Ifaluk (400 people) they have a radical different emotional life, the idea of happiness was radically different, their central emotion was compassion.
Relativise - The meaning of an emotion is relative: it depends on the culture
Triggers of embarrassment activate different areas of the brain across cultures.
