Database Comparisons: Age effects

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Database ComparisonsAge effects
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EEG age effects by hemisphere
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Dominant (alpha) rhythm

• Normal EEG pre-school to Adolescence
• Occipital rhythm
• 3-4 Hz activity at 3-4 months of age
• responds to stimulation at 5-6 mo. 
• At 6 mo, typically 5-6 Hz
• At 1 year, 6-7 Hz.
• Frequency range increases as child ages.
• Typical 10y old averages about 10 Hz.

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Dominant frequencies during infancy
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Othmer clinic data
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Normal Child has theta rhythm, maximal in
posterior sites
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Normal Adult has 8-12 Hz rhythm, maximal in
posterior sites
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Posterior sites
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Neurometic Analysis(Comparing someone to a QEEG
Database to identify statistical abnormality,
commonly gt 2 Std deviations, plus or minus)

• Baseline conditions
• Eyes closed
• Eyes open
• Motor control
• Stimulus control
• Task conditions or challenge conditions
• Problem solving
• Performance

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Eyes closed replications support macrostate
concept (however)
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Correct for state transitionsStabilize state
before recording, and include stabilization in
database!Look at the dataMore is
better(Some db use 30 s only)
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Client comparison requires similar recording
methodology
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Criticisms of Neurometrics

• Color maps are deceptive1
• Too many statistical tests (inflating Type I
  errors)
• Some normals appear abnormal to controls
• Overly sensitive to artifact
• More removed from the data, the more errors that
  can creep in
• E.g., unreliable discriminant functions

• Methodology differences between client and
  database recordings
• Artifact management differences
• Normative database not representative2
• Differences in basic parameters (power/magn),
  coherence calculation
• Not ready for prime time
• if misused!

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Brain maps can be deceptive ..

• Some activation needed at left medial temporal
  site or right occipitoparietal juncture?

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But they are convincing, concise, and accessible
to laypersons
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5 Neurometric databases in common use for
Neurotherapy

• My kid acting like an astronaut story

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Deciphering Neural codingWe transform from time
to frequency because we believe mental or
psychophysiological phenomena are best captured
by latter domain
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Brainwave frequencies and tentative mental
correspondences

• 0.5 4 Hz DELTA Sleep
• 4-7 Hz THETA Inward focus, distracted,
  daydream
• 8-12 Hz ALPHA Relaxed, not actively
  processing
• 12-15 Hz SMR Relaxed, external attention
• (low beta)
• 15-18 Hz BETA Active external attention
• 19-35 Hz HIGH High correlation with anxiety,
  
• BETA intensity, or lots of
  muscle tension.

 
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Alpha activation or arousal
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Activation is inversely proportional to alpha
activity incidence

• To some extent, regardless of topography

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10-10 International System of Electrode Placement
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Preferential site activation depends on the
condition

• Moving joystick
• Watching movie?

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Topographic Activation Patterns
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Laterality differences

• Everyone is a left-brainers until films make
  them integrationalists

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Gender differences
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Cerebral Organization Variation (and obstacles
to neurometric assessment)Trait and State
variables

• TRAIT
• Gender
• Handedness
• Age
• Education
• Experience
• Neurological present/history
• Bilingual
• Diagnosis!

• STATE
• Task competence
• practice
• Task strategies
• Time of Day
• Drugs
• Sleep debt

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Be aware of the plasticity spectrum people
change
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Inclusion/Exclusion criteria for normals
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Other factors
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Jareds spindles
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Measurement parameters

• Relative vs Absolute
• Power/magnitude
• Connectivity or linear dependency
• Asymmetry
• Coherence, comodulation

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Synchrony measures between two signals
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Coherence
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Coherence Database
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Comodulation (Functional grouping in dominant
frequency activity)
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Consistency or stationarity of amplitudes between
two signals in frequency band
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MVA or Youthful
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LORETALow resolution EEG tomographical array
(source imaging of maximal smoothness)
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Current EEG Applications

• CLINICAL
• Epilepsy (1930s)
• Sleep (1940s)
• Patient monitoring, anaesthesia
• Head injury assessment
• Neurological assessment (AEP, ERP)
• Neurotherapy
• Psychiatric assessment

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Current EEG Applications

• SCIENTIFIC
• Attention
• Workload
• Circadian rhythms
• Cognition
• Learning Memory
• Neuroimaging co-registration

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Future EEG Assessment

• Subtype clinical conditions
• Monitor attentional state
• Lie Detection
• Parole disposition