Whats UpThe Neurobiology of Learning and Adolescent Substance Abuse

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Whats Up-The Neurobiology of Learning and
Adolescent Substance Abuse

• Merrill Norton Pharm.D.,D. Ph., NCAC II, CCS
• Clinical Associate Professor
• University of Georgia
• College of Pharmacy
• Athens,Georgia 30602
• 706-542-5371
• mnorton_at_rx.uga.edu

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How are human behaviors and neurobiology related?
Neurobiology and Behavior
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Learning

• ...relatively permanent changes in behavior
  produced by experience
• Learning involves changes in the nervous system
  produced by experiences
• Nervous system changes are physical
• Learning allows us to adapt our behaviors to the
  environment
• Learning involves interactions among the motor,
  sensory, and memory systems

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Forms of Learning

• Perceptual learning functions to identify objects
  and situations
• Stimulus-Response learning involves making a
  response when a particular stimulus is present
• Classical conditioning
• Operant Conditioning
• Motor learning involves forming new circuits in
  motor system
• Relational learning involves identifying
  connections between stimuli

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Overview of Learning
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Relational Learning

• Relational learning involves connections between
  individual stimuli
• Examples of relational learning include
• Forming an association between the image of an
  object and the sounds of that object
• Knowing the content of a space and the
  relationship between the objects in that space
  (spatial learning)
• Remembering sequences of events (episodic
  learning)
• Viewing and recalling the actions of another
  person (observational learning)

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The Hebb Rule

• Donald Hebb argued that synapses that are active
  at the same time that the postsynaptic neuron
  fires, are strengthened over time
• Implies that repeated neural activity will
  produce physical changes in the nervous system
• Rats exposed to enriched environments exhibit
  neural changes
• Thicker cortex
• More glial cells
• More Acetylcholine(Long term Memory)

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Neurobiological Foundations of Mental Health and
Illness (Modified from Andreasen and Black, 2001)

• Thoughts, Feelings, and Behavior
• Mind/Brain Systems (mental/cognitive systems such
  as emotion or language, chemical systems such as
  dopamine or serotonin).
• Circuits
• Cells
• Membranes
• Molecules
• Genes

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Limbic Cortex and Hypothalamus
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Forebrain
Brain CEO Frontal Cortex
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The Oops Center anterior cingulate gyrus

• The cingulate is responsible for helping focus
  attention
• Links cingulate and emotional hippocampus for
  integrating reason emotion to guide decisions
• May involve ability to empathize
• Undergoes high myelination (doubles) during
  adolescence
• Oops center anticipates risk, detects and keeps
  us from making errors

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Myelin Development
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Developmental Model of Psychopathology
2 4-5 6-7 12
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MOS
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Autism
Eating Disorder Identity Disorder Abuse/ Dependenc
e
ODD Conduct Disorder
Eating Disorder Schizophrenia Depression Abuse/ De
pendence
Schizoid Reactive Attachment Separation Anxiety
Tourettes PDD Mental Retardation Anxiety
ODD ADHD Separation Anxiety Overanxious
Conduct Disorder Abuse/ Dependence
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Mood Chart of the Human Brain
Homeostasis
Mania
Euphoria
Normal
Sadness
Depression
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How Drugs Work

• Interact with neurochemistry
• Results
• - Feel Good Euphoria/reward
• - Feel Better Reduce negative feelings

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Dopamine Spells REWARD
Release
Recycle
Activate
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What memories do you associate with this image?

• visual
• colour
• shape

smell
language
taste
emotions
auditory
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Basal Ganglia- The Secretary
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Limbic System- The Driver
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Brain Development/Aging

• Recent research(imaging studies) have given
  scientists an estimate of brain chemistry
  development
• Age 11 - 50 complete (pre-puberty)
• Age 18 - 75 complete(post puberty)
• Age 24-34 - 100 complete
• Age 44 - 75
• Age 60 - 50

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Addiction Risk Factors

• Genetics
• Young Age of Onset
• Childhood Trauma (violent, sexual)
• Learning Disorders (ADD/ADHD)
• Mental Illness
• Depression
• Bipolar Disorder
• Psychosis

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NORMAL BRAIN
 
Thinking Brain
                                           
Rational Animals
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Cortex
Planning Inhibitions Sensorium
Midbrain   Personality Perception
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Diagam_Brain Normal C.
Diagam_Brain Normal C.
Diagam_Brain Normal C.
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HICC Hypothalamic Instinctual Control Centers
6 FS Food Intake Feelings Fluid Intake
Fight Flirtations Flight
NORMAL BRAIN FUNCTIONS     Diagam_Brain Normal
C.
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The Necessary Nine

• Norepinephrine/Epinephrine-stimulant,anger,fear,an
  xiety,fight,flight
• Serotonin-depressant,sleep,calm,pleasure
• GABA-relaxant,stress reduction,seizure threshold
• Endorphins-pain relief,pleasure
• Acetylcholine-involutary actions,memory,motivation
  
• Anandamide-memory,new learning,calmness
• Glutamate-organization of brain
  signaling,memory,pain
• Dopamine-perception,movement,pleasure
• PIP- loving of ones self,others,GOD

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norepinephrine
GABA
serotonin
cannabinoid
Alcohol Benzodiazepines Valium Xanax Ativan Non
benzodiazepine Ambien Sonata Barbiturates Fiorin
al Soma
Cocaine Amphetamine Methamphetamine Ephedrine Rita
lin
LSD Psilocibin DMT Ibogaine
Marijuana
opiate
NMDA
acetylcholine
Ecstasy Mescaline DOM
Opioids Opiates Heroin Buprenex Oxycontin
PCP Ketamine
Nicotine
GHB
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I want a beer
Thinking Brain
Judgment Brain
Instinctual Brain
It makes me feel goooood
Pleasure Brain
Miller Lite
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Neurotransmitters of Dependence
Dependence
Recovery
PIP Dopamine Glutamate Acetylcholine Anandamide En
dorphins / Enkelphins GABA Serotonin Epinephrine
/ Norepinephrine
Replenishment may take 5 to 7 years
Depletion may take less than 12 months
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Alcohol and the Adolescent Brain
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SPECT SCANS
Cocaine 2 yrs
Alcohol 25 yrs
Normal
Marijuana 12 yrs
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The Hijacking of the Brain and the HPA Axis
Cortisol
Exercise,Food,Psychoactive Chemicals
Endorphins
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Psychoactive Chemicals

• Alcohol
• Ecstasy/Methamphetamine
• Marijuana

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Alcohol as a Reinforcer Neural Systems
The Secretary
The Driver
Activation of mesocorticolimbic system
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Methamphetamine
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Methamphetamine
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Before and After
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Is Marijuana Addicting?
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The Brains Marijuana Receptor Sites
The Secretary
Fight or Flight
Coordination
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Brain Cannabinoid Receptors

• Basal Ganglia
• Unconscious muscle movements
• Limbic System
• Hippocampus
• Short term memory processed into long term memory
• Amygdala
• Controls rage, lust, fear and other strong
  emotions
• Cerebellum
• Balance and planning of movement

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Anandamide

• Sanskrit ananda means bliss
• Chemical messenger involved in mood, memory, pain
  perception and appetite
• Natural molecular key
• THC fits same receptor
• Anandamide is fragile and breaks down quickly
• No intense high like THC
• Chocolate

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MJ use Lowers Glucose Metabolism in Frontal and
Temporal Lobes
Temporal Gyri
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Marijuana Makes People Stupid and they stay
stupid..
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Multiple Neurotransmitter Receptor Sites For
Marijuana
Anandamide
Dopamine
GABA
Glutamate
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The Blood-Brain Barrier
THC Binds To Glial Cells of BBB
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The learned helplessness that results from
exposure to the absence of control generalizes to
other situations.
Marijuana creates the state of learned
helplessness.
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PSYCHOACTIVE CHEMICAL DEPENDENCE IS A COMPLEX
ILLNESS
www.drugabuse.gov