The Brain and Personality

• The Brain and Personality

  The scientific study of how and why people differ in characteristic patterns of thinking, feelings, and behaving
• Global Structure of the Brain

  • Two hemispheres
  • Four lobes
  • Functional localisation (e.g., frontal lobe responsible for executive functions like abstract thinking and planning)
• Personality


  Strong overlap with some functions of the frontal lobe
• The Limbic system


  • Consists of olfactory bulb, hypothalamus, hippocampus, amygdala, & cingulate gyrus of the cerebral cortex
  • Involved in the regulation of motivated and emotional behaviour (e.g., eating, drinking, sexual activity, anxiety, & aggression)
• The Limbic System - Eysenk's theory

  Definition of neuroticism as emotional stability to instability. This system is linked due to emotional behaviour
• The Limbic System - Gray's BIS/BAS theory

  Talked heavily about motivation and how motivation should be accounted for in a personality theory
• Mesocorticolimbic "Reward" Circuit


  • Key Pathway for 'reward' processing: Ventral tegmental area VTA, Striatum Nucleus Accumbens, Prefrontal cortex, Hippocampus, Amygdala
  • Neurotransmitters: Gamma-aminobutyric acid GABA, Glutamine, Dopamine
• DeYoung et al. 2010 assessed the association between the Big 5 personality traits and brain volume of different regions

  
• De Young - Extroversion

  Medial orbitofrontal cortex (reward processing)
• De Young - Conscientiousness

  Lateral prefrontal area (planning/control)
• De Young - Neuroticism

  Various regions (threat, punishment, negative affect)
• De Young - Agreeableness

  Various regions ("mind reading" (capacity to understand the intentions of others); intentions of others)
• Forsman et al. 2012 assessed neural correlates of Cattell's personality model, and reported that Extroverts had less white matter in areas that include ascending projections to parts of the cortex (behavioural control) and less grey matter in various parts of the cortex, especially right prefrontal & right temporo-parietal areas (restraint, introspection, & social intelligence)
• Traumatic Brain Injury (TBI)

  Brain damage which results from an injury with an obvious cause (e.g., gun shot, car crash, fall). Rated from mild (e.g., concussion) to severe (e.g., loss of consciousness for an extended period). Having more than one means slower recovery
• Acquired Brain Injury (ABI)

  Any type of (non-traumatic) brain damage that happens after birth. No obvious external cause (e.g., tumour, stroke, suffocation, infection, etc.)
• Physical Impacts of TBI

  • Motor skills, hearing, muscle control, speech, tiredness, seizures, taste, smell
• Cognitive Impacts of TBI

  • Memory, attention, problem solving, executive functioning, perceptions, language production and perception
• Personality & Behaviour Impacts of TBI

  • Anger, Irritability, Reduced social skills, Inability to recognise social cues, Emotion control, Inappropriate behaviour, Impulse control, Reduced self esteem, Difficulty maintaining relationships, Reduced frustration tolerance, Stress, Anxiety
• Morton & Wehman 1995 reviewed the TBI literature and reported 4 common themes: high risk for significant decrease in friendships & social support, lack of opportunity to make new social contacts & friends, decreased leisure activities, increased instances of depression and anxiety
• TBI associated with increased social isolation, and increased dependence on others
• Phineas Gage suffered a severe, penetrating brain injury in 1848 (age 25). The rod entered his skull below his left cheek bone and exited after passing through the anterior frontal lobe of his brain. He made a remarkable recovery, living 11 more years, although there were noticeable changes reported in his personality, reasoning, and capacity to understand and follow social norms
• Van Horn et al. 2012 estimated that 4% of Gage's cortex, and 11% of white matter, was destroyed in the frontal lobe. This included tracts connecting the frontal cortex to limbic (emotional) areas
• After the accident Gage was described as a nasty, vulgar, irresponsible vagrant
• Mukherjee et al. 2006 describe the psychological phenomena associated with strokes and post-stroke adaptation: increased risk for depression and anxiety, changes in identity and personality processes, potential for social isolation. Very similar to those seen in traumatic brain injury
• Other psychological impairments typically reported after stroke

  • Attention, memory function (including visuospatial), emotional control, emotional liability (rapid, often exaggerated changes in mood, where strong emotions or feelings occur), inappropriate or blunted affect, language ability, ability to add tone to voice when speaking (prosody), sensory loss, change in interests, apathetic
• Parkinson's Disease

  • Breakdown in dopamine producing cells: degeneration of dopamine pathways from substantia nigra to the striatum, decreased volume of dopamine
• The 'Parkinsonian Personality'


  Increased neuroticism, low levels of openness and extraversion, low novelty seeking, high harm avoidance, share several clinical features with obsessive compulsive personality disorder

  
• Kaasinen et al. 2002 found that the results on the 'Parkinsonian Personality' cannot be replicated in healthy elderly population