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Transcript of 10/11/2015 Underlying Neuroscience Principles in Brain Injury Litigation n Larry J. Cohen n Arizona...
04/19/23
Underlying Neuroscience Principles in Brain Injury Litigation
Larry J. Cohen Arizona Attorney General November 7, 2014 Phoenix, Arizona
Agenda
Neuroanatomy– Neural Circuits and Networks
Regulation Assessment
– Neuropsychology Imaging Assessment
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Critical Operations to be Carried out by the Nervous System Process Information about the External
Environment Prepare and Execute Actions Encode, Store and Access Information Communicate Select Control and Monitor Complex
Operations
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Fundamentals of Neuroanatomy
Historical View Focused on Areas of the Brain Responsible for Behavior of Interest– Brain Stem: Controls basic functions– Frontal: Management and Expressive Language– Temporal: Processing Information; Receptive
Language; Hearing and Memory– Parietal: Motor and Sensory– Occipital: Vision
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Subcortical Structures
Hippocampus– Associated with memory function– Encoding
• Memory consolidation• Damage prevents explicit descriptions of
events cannot be learned (episodic memory)• But can still give some meaning and knowledge
to experience (semantic)
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Subcortical Structures
Cerebellum– Learning of Procedural Memory; motor
learning• Coordination• Fine Motor Control• Damage can cause problems with movement
and coordination
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Subcortical Structures
Amygdala– Associated with emotional learning and
memory• Process results in emotional events being more
deeply and accurately encoded into memory• Also important in memory consolidation
– By ascribing value to events
• Damage impairs motivation and processing of emotions
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Subcortical Structures
Basal Ganglia– Associated with learning, memory and
unconscious memory processes• Motor skills and implicit memory
– Damage is associated with dysfunctional learning of motor and perceptual-motor skills
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Subcortical Structures
Thalmus– Implicated in control of sleep and attention– Relay station that receives input from eyes,
ears, spinal cord• Role in relaying information to the cerebral
cortex
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Subcortical Structures
Reticular Activating System– Densely packed cells in thee central core
of the hindbrain– Thought to activate the thalmus and the
cortex– Damage to this system compromises
wakefullness
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Neural Circuits or Networks
Neural Networks: Interconnected ensembles of cortical and subcortical neurons co-activated to mediate cognitive or behavioral Function
Link structures within the brain– Distributed Cells with Regional specialization– Critical Hubs– Similar Clinical Outcomes from Injury to Different
Parts of the Circuits04/19/23
Conditions Affecting Networks
Multifocal Insults (TBI, Demyelinating disease)
Focal Insults (stroke, tumor) Developmental Sndromes (ADHD) Normal Age Related Cognitive Changes CNS Infections Neurdegenerative Disease Vascular Cognitive Impairment04/19/23
Neurodevelopment Nervous system is derived from the
outermost tissue layer of the embryo– Subject to damage when exposed to disease,
toxins or trauma After birth development continues through
a process of sprouting and pruning– Believed to continue until early 20’s– Organic basis to account for behavior
through development
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Regulation
Self-Adjustment to Address Distress in the Environment– Use of Energy in Response to Distress
Helps the Individual Return to a Preferred State– Internal– External
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Issues in Neuropsychological Evaluation Estimating Premorbid Baselines
– Individual• History• Hold Functions
– Population• Base Rates
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Issues in Neuropsychological Evaluation Current Brain Behavior Relationships
– Level of Consciousness– Comportment – Interpersonal relationships relative to the
individual– Attention– Executive Function– Orientation– Memory– Language Visuospatial Function– Motor Function– Mood
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Issues in Traumatic Brain Injury TBI Defined
– Force Acting on the Brain• Disturbs levels of consciousness
– Continuum of Injury• Primary
– Direct– Rotational
• Secondary– Interaction with other on-going processes
Distinguish from– Acquired Brain Injury (e.g. stroke)– Developmental Disorders
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Physical Injury from Contact and Inertial Mechanisms Primary Injury
– Occurs Immediately• Contusions• Hemorrhages• Diffuse Axonal Injury
Secondary Injury– Evolves Over Time
• Massive Release of Neurotransmittors• Edema.Ischemia/Hypoxia• Increased intracranial pressure• Triggering of Excitotoxins
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Visualization of Physical Injury
Ability to Detect Depends on Ability to Image– Damage to Tissue– Bleeding
Problematic where Damage at the cellular level– Diffuse Axonal Injury
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Tertiary Factors That Compromise Assessment Interaction with Other Physical
Conditions Delay in focus on consequences of TBI Potentiation by Environmental Factors Social-Environment Dynamics Secondary Gain Measurement Limitations
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Immediate Consequences Cognitive Deficits Personality Changes
– Social Comportment
– Motivation
– Personal Management (Executive) Psychiatric Disorders
– Due to overlap of TBI and Psychiatric Disorders with respect to the Distribution of Neural Circuitry that Mediates Mood regulation, stress response, impulse control and reward modulation
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Long Term Consequences
Compromises Plasticity– Increases Vulnerability to Developmental
Processes and Disease Reliance on Compensatory Techniques
that May be Compromised Over Time
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Status of Knowledge About TBI
“Emerging science but persistent absence of evidence”
Treatment not Distinctive– Apply Methods Applicable to Other Kinds
of Disorders
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Future Brain Injury Assessment Genetics
– APOE• Provides instructions for making a protein called
apolipoprotein E. • Combines with fats (lipids) in the body to form molecules
called lipoproteins.• Lipoproteins are responsible for packaging cholesterol and
other fats and carrying them through the bloodstream. – Apolipoprotein E is a major component of a specific type of
lipoprotein called very low-density lipoproteins (VLDLs). VLDLs remove excess cholesterol from the blood and carries it to the liver for processing.
– Maintaining normal levels of cholesterol is essential for the prevention of disorders that affect the heart and blood vessel
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Future Brain Injury Assessment
Genetics– APOE
• Amyloid Deposition• Disruption of Cytoskeletal Stability• Cholnergic Dysfunction• Oxydative Stress• Neuroprotection• Central Nervous System Plasticity
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Future Brain Injury
Genetics– Other Genes
• COMT and DRD2 may influence dopamine dependent cognitive processes
– Executive Frontal Lobe Functions
• Interkeukin Genes– Affects inflamatory processes
• ACE Gene– Affects cerebral blood flow
• CACNA1A– Affects calcium channels and so contribute to edema
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