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Why We Do What We Do
Alan B. Grindal MD
In order to overcome our failures and
vulnerabilities as both individuals and
societies, we must first understand our
biologic predispositions and the evolutionary
behavioral traits which have made us human.
Introduction
The body has needs and the
environment has resources. The
brain attempts to match the two
and create stability. Basic drives
include individual and genetic
survival.
Outline
• Introduction to the brain.
• Human behavior and evolution
• Morality
• Free Will
• Violence
• Love and attachment
Brain Complexity
• 100 billion neurons
• 150,000,000,000,000 (150
trillion) synapses
• 100,000 miles of nerve fibers
• Prenatal brain makes 5000 new
neurons a second.
• 1 cubic millimeter of brain cortex
contains 1 billion synapses.
The brain is complicated. There are no simple answers.
The Ice-cream Cone Analogy
Basic Anatomy-Brainstem
• Basic functions: ascending and
descending nerve tracts,
unconscious reflexes, regulation of
sleep.
• Cranial Nerves
• Reticular activating system (RAS)”the light switch”
• Thalamus-relay center and a
rheostat
• Hypothalamus- Control of internal
milieu
• Cerebellum- coordination
Limbic Functions
• Regulates instinctual behavior, emotion,
motivational drive, and memory.
• Primary emotions of fear, anger, sorrow, joy
and disgust.
• Primary drives of hunger, thirst, sex, defense
and aggression.
• Weighs needs against dangers.
• Conflict when primary drives conflict with
social rules.
Cerebral Hemispheres
• Occipital - Vision and visual
memory
• Parietal - Body orientation,
calculation and sensory function
• Temporal – Auditory, emotional
control, memory (hippocampus),
facial recognition.
• Frontal – Motor control, impulse
control, and executive function
A Dichotomous Relationship
Left Brain
Right Brain
• Expressive, verbal
• Logical, detailed
• Concrete
• Social emotions
• Factual Memory
• “Left Hemisphere Interpreter”
• Perceptual, spatial
• Holistic, creative
• Metaphorical
• Primary emotions
• Emotional autobiographical
memory
Left Hemisphere
• Communication and verbal
behavior-literal meaning, discrete
units (prose)
• Fine motor control ie.handedness
• Conscious planning
• Categorization-duality
• Integrator- constructs a world
based on available information.
Resolves conflict.
• Social emotion- pride, shame,
embarrassment,
Right Hemisphere
• Close relationship to Limbic system
and primary emotional valence and
familiarity.
• Sensitive to rhythm and repetition
i.e.. poetry, music, and religion
• Spatial orientation.
• Self-monitoring and Ego
boundaries.
• Prosody and non-verbal
expression.
• Appreciation of humor.
Interhemispheric Communication
• Corpus Callosum
• Coordinate and integrate. Ex#
bimanual tasks.
• Competitive and deactivating
• Callosectomy- two minds
Serial v. Parallel Processing
• Serial- Information processed with
increasing integration and complexity
eg. A dot to a line to a shape.
• Parallel- Independent serial processes
can occur simultaneously and can
combine and compete with each
other.
• Unconscious- parallel. Consciousserial
• Emphasis on connectivity as well as
location.
Plasticity
• Changeability and remodeling
with learning and experience
• Nerves that fire together wire
together
• Change in synaptic strength,
sprouting of dendrites, new
nerve cells
• Braille readers, musicians
• Limited capacity with aging
Neuronal Pruning
• Decrease connections- greater
specificity and efficiency.
• Primarily during late fetal stages
and infancy- eliminates “noise”
in the system.
• “ Use it or lose it”
• Neural Darwinism
Small World Networks
• Networks- Nodes, edges and hubs
• Systems of functionality ( Sensory,
attention, language, salience and
executive)
• Systems build in complexity and
interactivity.
• Autism- Increase connections in
sensory systems
• ADHD- Decrease connections –
primarily in attention systems
Glial cells
• Astrocytes- Provide scaffolding,
regulate synapse and control
blood brain barrier- Brain
tumors.
• Oligodendroglia- Form myelin
sheets to promote rapid
conduction.- Multiple Sclerosis.
• Microglia- Inflammatory
response and scavengers.