Lecture 6 - Personality Flashcards
What is the heritability of personality?
•Heritability estimates for personality traits are typically around 50% or higher, indicating that sources of personality lie in both the genome and the environment.
Neuroanatomy of Self
•Two areas of the brain that are important in retrieving self-knowledge are the medial prefrontal cortex and the medial posterior parietal cortex.
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•The posterior cingulate cortex, the anterior cingulate cortex, and medial prefrontal cortex are thought to combine to provide humans with the ability to self-reflect.
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•The insular cortex is also thought to be involved in the process of self-reference.
Frontal lobe and personality
The “control panel” of personality:
- Controls important cognitive skills in humans, such as emotional expression, problem solving, memory, language, judgment, and sexual behaviors.
- Relevant to movement, attention, executive functioning, language and social behavior.
- “the cortical locus of “higher learning”’
- Frontal lobe function is thought to impinge on the entire repertoire of behaviour.
- This involvement of the frontal lobes in many aspects of behaviour is reflected in its massive connections with other brain areas.
- These connections are made through the limbic system, thalamus and hypothalamus.
Three key roles of Frontal Lobe:
1) Mediate the ability to engage in abstract thought.
2) Organise behaviour in logical sequence and in temporal order.
3) Inhibit responses to the environment.
Also,
Managing attention, including selective attention:
- When the frontal lobe cannot properly manage attention àconditions such as ADHD.
Planning,
Memory and visualization.
List 3 fields of abstract thought that the Frontal Lobe deals with
Social Cognition:
•Uses long term memory to guide social behaviors in routine and novel situations.
Decision Making:
•Abstract thought is demonstrated when subjects have to make decisions based on other previous decisions.
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Empathy:understanding and reacting to the feelings of others.
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Development of Abstract thought and the Frontal Lobe
•Middle to late adolescence is a magical time for the frontal lobes and neo-cortex.
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•Development of frontal lobes usually happens between the ages of 15 and 18 but ONLY if it’s allowed to happen.
What parts of the FL helps with strategic and coordinated planning?
•It is the anterior (front) and dorsolateral (top and sides) parts of our frontal lobes that help perform strategic and coordinated planning.
Organization of behaviour (FL)
Integration of Processes
•Abstract Thought:
Sally might be upset if I took the last cupcake (Imagination, visualization, memory, empathy).
•Organization of Behaviour:
Diversion of motor movement from cupcake to less preferred cookie, planning around what item would bother Sally less if I take it.
•Response Inhibition:
Stopping myself from taking the cupcake
Theories of Frontal Lobe Function (8)
- Classical
- Supervisory Attentional System
- Stimulus Reward
- Somatic Marker
- Working Memory
- Genetics
- Five Factor Model
- Biological
The Classical View of FL function
Luria (1973):
•Viewed the frontal lobes as a principal brain unit responsible for programming, regulating and verifying human behaviour.
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•When complex programmes of activity are disrupted, simpler more basic forms of behaviour might replace them or they might be replaced by stereotypical behaviour that is either irrelevant to the situation or illogical.
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•Different prefrontal systems are thought to inhibit different posterior cortex areas.
Supervisory Attentional System view of FL function
•Theory states that the frontal lobes programme, regulate and verify activity.
Contention Scheduling: initiates appropriate schema under routine, well-learned situations by inhibiting competing schemas.
Supervisory Attentional System: controls schema activation under unique, non-routine procedures. Oversees contention scheduling by influencing schema activation probabilities and allowing for general strategies to be applied to novel situations.
- The SAS influences the probability of a schema being selected by contention scheduling.
- The SAS is involved in planning/decision making, error correcting, requiring responses that are neither well learned or familiar, considered to be dangerous or difficult, and requiring the organism to ignorestrong habitual responses.
Stimulus-Reward (theory of FL function)
Rolls’sTheory of Orbitofrontal Function:
- Regards emotions as states produced by reinforcing stimuli.
- Argues that frontal lobe damage results in failure to react normally to non-reward in different contexts.
- Therefore, inappropriate responses to stimuli will appear when those responses are not rewarded.
Somatic Marker Hypothesis (of FL function)
Damasio’s Theory:
- Attempts to explain the role of the frontal cortex in emotion and social behaviour.
- Suggests that although a patient with frontal lobe damage may be able to understand the implications of inappropriate social behaviour, they are unable to mark these implications with a signal that automatically distinguishes between appropriate and inappropriate actions.
- In other words, social learning is derived from punishment or reward associations.
- These modify somatic states and send signals to sensory and limbic areas which enable the consequences of reward/punishment to be experienced as feelings/emotions.
Working Memory Hypothesis (of FL function)
Baddeley (1996):
•Characterized frontal lobe dysfunction as a “dysexecutive” syndrome involving the disruption of working memory.
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•Working memory represents the mental process of movement to movement awareness and instant retrieval of archived information (“the blackboard of the mind”).
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•The most important part of WM is the central executive which is thought to control resources and monitor information processing.
Central Executive
What is the Nucleus Accumbens
- The nucleus accumbensis an aggregate of neurons which is described as having an outer shell and an inner core.
- Has a significant role in the cognitive processing of motivation, aversion, reward (ie. Incentive, salience, pleasure and positive reinforcement) and reinforcement learning.
- Approximately 95% of neurons in the NAccare GABAergic which primarily express dopamingergicreceptors.
