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Functional neuroimaging of anxie

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					Functional neuroimaging of
         anxiety
  A meta-analysis of emotional
   processing in PTSD, social
  anxiety disorder and specific
             phobia
              Objective
• Find common and disorder-specific
  functional neurobiological deficits in
  anxiety disorders.
• Compare findings to systems engaged
  during anticipatory anxiety in healthy
  subjects.
                Method
• A comparative quantitative meta-
  analysis of FMRI and PET of studies:
  - Post traumatic stress disorder
  - Social anxiety disorder
  - Specific phobias
  - Anticipatory anxiety in healthy subjects
                  PTSD
• Anxiety disorder developed after
  psychological trauma.
• Involving reexperience. (nightmares and
  flashbacks)
• Avoidance of triggers. (Stimuli that is
  associated with trauma)
• Symptoms of increased arousal. (Sleep and
  concentration problems)
• Lasting more than one month.
     Social anxiety disorder
• Fear regarding social activities.
  Of being humiliated or embarrassed by
  their actions.
• Leading to avoidance of social
  situations.
                 Phobia
• Form Greek “phobos” meaning fear.
• Irrational, intense, persistent fear of
  certain situations, objects, activities or
  persons.
• Excessive desire to avoid the feared
  subject.
               Anxiety
• Previous negative experience.
• Stimulus associated with this
  experience trigger defensive behavior.
• Defensive behavior involve avoiding
  triggers.
• Lead to impaired life quality if
  excessive.
          Maintaining anxiety
• Operant conditioning;
• when we see or encounter something associated with
  a previous traumatic experience, anxious feelings
  resurface.
• We feel temporarily relieved when we avoid
  situations which make us anxious, but this only
  increases anxious feelings the next time we are in the
  same position, and we will want to escape the
  situation again and therefore will not make any
  progress against the anxiety.
          Fear in the brain
• It has long been known that fear is
  associated with activation of amygdala.
• Studies have shown inconsistencies in
  the activity of other nuclei during fear
  response in humans.
                   Amygdala
• Research indicates that, during fear conditioning,
  sensory stimuli reach the Amygdala where it forms
  associations with memories of the stimuli.
• Involved in the genesis of many fear responses,
  including freezing, tachycardia, increased respiration,
  and stress-hormone release.
• Damage to the amygdalae impairs both the
  acquisition and expression of Pavlovian fear
  conditioning
• The amygdalae, especially the basolateral nuclei, are
  involved in mediating the effects of emotional arousal
  on the strength of the memory for the event
            Lobus insularis
• The insula is believed to process convergent
  information to produce an emotionally
  relevant context for sensory experience.
• Functional imaging experiments have
  revealed that the insula has an important role
  in pain experience and the experience of a
  number of basic emotions, including anger,
  fear, disgust, happiness and sadness.
           Results PTSD
• Hyperactivity in Amygdalae,
  Parahippocampal gyrus, Insula, Inferior
  parietal lobe, Mid-cingulate and
  Precuneus cortex.
• Hypoactivity in many cortical areas and
  some amygdalar nuclei.
Results social anxiety disorder
• Hyperactivity in amygdalae,
  parahippocampal and fusiform gyrus,
  globus pallidus, insula, inferior frontal
  and superior temporal gyrus.
• No hypoactivity.
     Results specific phobia
• Hyperactivity in amygdalae, fusiform
  gyrus, globus pallidus, insula, inferior
  frontal and superior temporal gyrus.
• No hypoactivity.
             Discussion
• Amygdala and insula are the only two
  areas showing consistent hyperactivity
  in the three disorders.
• PTSD is a complex disorder where fear
  is only one component.
• Social anxiety and phobias may be
  more readily described as intense fear.
             Conclusion
• Social anxiety disorder and Phobias are
  comparable with fear in healthy
  subjects.
• PTSD however has fear as one
  component, but has a other
  components too.

				
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posted:10/12/2010
language:English
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