Neuroscience of Personality & Brain Plasticity Notes

Phineas Gage Case Study

• The Accident (1848):

  • Phineas Gage was working on a railroad in Vermont.
  • He used a tamping iron to pack explosive powder.
  • A spark triggered an explosion.
  • The iron rod went through his skull, entering his cheek and exiting through the top of his head.

• Miraculous Survival:

  • Gage remained conscious despite the severe brain injury.
  • He could walk and talk shortly after the accident.
  • He eventually recovered physically.

• Personality Change:

  • Gage's behavior changed drastically after the accident.
  • He became impulsive, profane, and unreliable.
  • This was a stark contrast to his former responsible self.

• Frontal Lobe Damage:

  • The iron rod destroyed part of his left frontal lobe.
  • Specifically, the ventromedial region was damaged.
  • This region is now known to be involved in personality and decision-making.

• Legacy in Neuroscience:

  • The case of Phineas Gage became a landmark in understanding the relationship between brain structures and personality.
  • It influenced ideas about brain regions and function.

Brain Regions & Functions

The brain regions and functions include:

• Seeing
• Hearing
• Touching & Moving
• Talking

Brain Plasticity

• Brain plasticity is defined as the brain's ability to adapt and change in response to internal and external demands.

• Brain plasticity can be:

  • Transient
  • Permanent

Brain Scans

• MRI: Magnetic Resonance Imaging

• Functional MRI (fMRI): captures the function of the brain

• Structural MRI (sMRI or MRI): captures the structure of the brain

fMRI versus (s)MRI

• Utilize the same scanner.
• Employ the same signal.
• fMRI measures levels of oxygen in the blood.
• sMRI measures levels of water in the tissue.
• fMRI captures brain activity.
• sMRI captures brain anatomy.
• fMRI typically has a shorter scan time compared to sMRI, which has a longer scan time.
• During fMRI, it's important to remain still.

Brain Structure

• Skull
• Meninges
• Brain
• Gray Matter
• White Matter
• Cerebrospinal Fluid (CSF)

Brain Plasticity Studies

• Taxi Drivers (2000)

  • Maguire et al. 2000 (PNAS)
  • Showed more brain tissue in an area responsible for memory formation.

• Musicians (2003)

  • Gaser et al. 2003 (Journal of Neuroscience)
  • Demonstrated more brain tissue in areas responsible for the processing of auditory, somatosensory, visuo-spatial, and motor information.

• Jugglers (2004)

  • Draganski et al. 2004 (Nature)
  • Showed increased brain tissue in an area responsible for the spatial perception and anticipation of moving objects.

• Students (2006)

  • Draganski et al. 2006 (Journal of Neuroscience)
  • Revealed increased brain tissue in an area responsible for memory storage, specifically in the Hippocampus.

Cross-Sectional Studies

• Involve Group A and Group B.
• Aim to determine if an observation is a consequence or a cause.

Longitudinal Studies

• Involve training Group A and observing consequences.

Meditation Project

• Meditation Project (2007-2017) took place in the Greater Los Angeles Area.

• Involved researchers at LONI (Laboratory of Neuro Imaging, UCLA) studying brain plasticity.

• Recruited active meditators with more than 5 years of meditation experience.

• Participants:

  • > 18 years old
  • ≥ 5 years of meditation
  • without contra-indications for MRI
  • Monks, School Teachers, Musicians, Massage Therapists, Physicians, Actors, Social Workers, Lawyers, University Professors, Journalists and Nurses.

• Demographics:

  • more than 50 meditators
  • between 24 - 77 years of age (mean age: 51 years)
  • between 5 - 46 years of practice (mean practice: 21 years)

MRI Scanning Safety

• DANGER: STRONG MAGNETIC FIELD
• Magnet is always on.
• Notify the MRI technologist or radiologist if:
  • You have any metallic, electronic or magnetic implants or devices in your body
  • You have been exposed to metal shavings from operations like grinding or sawing as part of your occupation
  • You have metal embedded in your body due to injury
  • You have any object which may contain metal or metallic parts (cell phones, scissors, watches, hearing aids, tools or keys)
• Failure to follow these instructions could result in serious injury or death.

Meditation Project Details

• Meditators: n=50
  • 22 Women / 28 Men
  • Age: 24 - 77 years
• Matched to 50 healthy controls
  • Pair-wise: Biological Sex | Chronological Age
  • Group-wise: Education
• Same Scanner
• Same Scanning Parameters

Meditation Project Analyses

• Analysis 1: Regional Volumes
• Analysis 2: Gray Matter Concentration
• Analysis 3: White Matter Fiber Integrity
• Analysis 4: Callosal Thickness
• Analysis 5: Hippocampal Distances
• Analysis 6: Cortical Gyrification
• Meditators > Controls

Cortical Gyrification & Functional Implications

• Anterior Insula
  • “hub” for affective, autonomic, and cognitive integration.
  • Meditators = masters in introspection, awareness, emotional control, and self-regulation.
  • Increased (self)awareness?

Potential Benefits of Meditation Inferred

• Better working memory?
• Increased behavioral flexibility?
• Enhanced hemispheric integration?
• Down-regulation of stress?
• Increased (self)awareness?

Other Studies on Meditation

• Blue regions = reported in one study
• Yellow regions = reported in two studies
• Pink regions = reported in three or more studies
• Luders et al. 2018 (Current Opinion in Psychology)

Cause or Consequence?

• Are larger measures the consequence of meditation?
• Are larger measures the cause for meditation?

Longitudinal Studies on Meditation

• Holzel et al. (2010) - Study I
• Tang et al. (2010) - Study II

Study Details

Conclusions on Meditation Research

• There is a link between meditation and brain structure
• The link is evident in many brain regions
• Meditation causes changes in brain structure - Longitudinal studies