Using EventRelated Potentials ERPs to Investigate the Neuropathophysiology of Pediatric Affective Di

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• Using Event-Related Potentials (ERPs) to
  Investigate the Neuropathophysiology of Pediatric
  Affective Disorders
• Cecile D. Ladouceur, Ph.D.
• Assistant Professor of Psychiatry
• Western Psychiatric Institute Clinic
• June 21, 2007

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Basics of ERP Techniques

• Brain generated electrical activity is measured
  by electrodes on the surface of the
  scalp.
• Scalp recorded electrical activity is thought to
  reflect the intermittent synchronization of small
  populations of predominantly cortical neurons.
• The signal measured at any one electrode is not
  an absolute voltage, but a relative one.
• An event-related potential (ERP) is the average
  response evoked by a particular type of stimulus
  or response.

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DENSE ARRAY EEG
Geodesic Sensor Net (EGI Inc.)
(Reference www. egi.com)
(Reference http//hdeegerp.psych.sc.edu)
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Deriving ERPs
Analog to Digital Converter
Data Acquisition Processing
Amplifier Filters
Experimental Computer (E-prime)
Subject Monitor
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EEG
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Averaging
(Reference http//www.rotman-baycrest.on.ca/conte
nt/science/eeg.html)
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Description of ERPs
Baseline
Area
Peak- to- Peak
Base- to- Peak
Peak Latency
Response Onset
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Pediatric Affective Disorders
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Pediatric Affective Disorders

• Anxiety disorders are among the most common child
  mental health problems (Roblek and Piacentini
  2005) affecting between 10-20 of youth (Pine
  1994 Shaffer et al 1996).
• As in adult anxiety disorders, pediatric anxiety
  disorders are characterized by hypervigilance,
  rapid automatic responses to threat and selective
  attention to threat (Vasey et al., 2001).
• Children diagnosed with an anxiety disorder are
  at greater risk of developing depression (Pine et
  al., 1998).

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Pediatric Affective Disorders

• There is evidence suggesting that anxiety and
  depression are associated with impairments in
  emotion regulation, namely difficulties
  regulating attention to emotional information and
  regulating emotion-related behavior.
• Focus neural correlates of processes at the
  interface of cognitive control processes and
  emotion as a way to understand the
  neuropathophysiology of pediatric affective
  disorders.

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Anterior Cingulate Cortex
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Cognitive Neuroscience Model of Cognitive Control
Carter et al., 1998, Botvinick et al., 2001
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Response Monitoring ERPs

• Error-related negativity (ERN)
• a sharp negative deflection in the EEG that
  occurs about 80 msec following errors
• localized to the dorsal region of the anterior
  cingulate cortex (ACC) in adults
• Error-related positivity (Pe)
• a positive deflection in the EEG that occurs
  about 200-400 msec following errors
• localized to the rostral region of the ACC in
  adults

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ERIKSEN FLANKER TASK


Time


100 ms
Congruent
Incongruent
(Correct Response Right)
(Correct Response Left)

• 840 trials (7 blocks) 1 practice block
• incentive cash bonus at the end

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Normal Development of the ERN and Pe
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Participant Characteristics
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Behavioral Performance Reaction Time
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Behavioral Performance Percentage of Errors
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Development of ERN and Pe
Old Adolescents
Young Adolescents
Adults
Pe
Pe
Pe
microvolts
msec
msec
msec
ERN
ERN
Ladouceur et al., 2007
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Summary

• Pe was present across groups.
• ERN was significantly greater in older
  adolescents
• adults compared to young adolescents, which
  suggests that
• there are important maturational changes in the
  ACC that take place later in adolescence
• these changes may be associated with increased
  sensitivity or more efficient error-related
  response monitoring processes
• These findings support recent developmental
  results regarding ERN and Pe (Davies et al.,
  2004) and set the foundation for work in clinical
  populations.

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ERN and Pe in Pediatric Anxiety Disorders
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ERN in Anxiety Disorder

• Increased ERN in
• Adults with OCD (Ghering et al., 2000)
• Adults high in trait anxiety (Hajcak et al.,
  2003)
• Adults high in negative affect (Hajcak et al.,
  2004)
• Neuropathophysiology of Anxiety Disorders
  over-activity of the ACC?
• Goal examine whether children with an anxiety
  disorder showed increased ERN/Pe

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ERN and Pe at Cz in Children with an Anxiety
Disorder
Low-risk Control Group
Anxiety Disorder Group
Pe
Pe
microvolts
msec
msec
ERN
Note No differences in behavioral performance
Ladouceur et al., 2006
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Topographic Map and Source Localization of ERN
in the Anxiety Disorder Group
Ladouceur et al., 2006
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Topographic Map and Source Localization of Pe in
the Anxiety Disorder and Low-risk Control Groups
Anxiety Disorder
Low-risk Control
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Effects of Treatment on ERN/Pe in Anxious
Children
Pe
microvolts
msec
ERN
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ERN and Pe in Pediatric Anxiety and Depression
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ERN in Depression

• Increased ERN in adult and pediatric anxiety
  disorders.
• Evidence of decreased ERN associated with adult
  depression along with oversensitivity to errors
  and perceived failure (Pizzagelli et al., 2006
  Ruchsow et al., 2004, 2006).
• Little is known about changes in ERN in
  pediatric depression and comorbid
  anxiety-depression.
• Examining distinctions within these clinical
  groups may have important implications for
  understanding neuropathophysiology of pediatric
  anxiety and depression and the developmental
  course from pediatric anxiety to depression.

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Participant Characteristics
Ladouceur et al., in prep
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ERN in Pediatric Anxiety, Depression, and
Comorbid Anxiety-Depression
Anxiety Disorder
Major Depression
Comorbid Anxiety-Depression
Low-risk Control
Note No significant differences in performance.
Ladouceur et al., in prep
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Increased ERN Amplitude to Errors in Anxiety but
not Depression
Ladouceur et al., in prep
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Conclusion

• ERPs are a useful tool to investigate the neural
  correlates of response monitoring processes in
  pediatric affective disorders.
• Source localization analyses provide information
  about the location of the neural generators of
  these ERPs, suggesting that differences in ERP
  amplitudes may be related to abnormalities in the
  development of the ACC.
• The goal of future studies is to
• include emotional stimuli or reward/punishment
  contingencies.
• cross-register ERP and fMRI data in order to
  obtain more a complete description of the neural
  correlates (temporal and spatial resolution) of
  response monitoring in pediatric affective
  disorders.