Introduction to EEG/QEEG/ERP
Quantitative ElectroEncephaloGraphy: QEEG
الکتروانسفالوگرافی کمی
Outline
▪️Rational for QEEG/ERP
▪️What is EEG and QEEG
▪️QEEG: Basic Concepts and features
▪️ Brain Map
▪️QEEG Database
طرح کلی
▪️منطقی برای QEEG/ERP
▪️EEG و QEEG چیست
▪️QEEG: مفاهیم و ویژگی های اساسی
▪️ نقشه مغز
▪️پایگاه داده QEEG
Rational for QEEG/ERP
▪️ As an objective tool in experimental studies
▪️Brain-behavior relationship
▪️As a suitable tool in studying of discrete information
منطقی برای QEEG/ERP
▪️ به عنوان ابزاری عینی در مطالعات تجربی
▪️رابطه مغز و رفتار
▪️به عنوان ابزاری مناسب در مطالعه اطلاعات گسسته
Rational for QEEG/ERP
As an objective tool in experimental studies
Rational for QEEG/ERP
As an objective tool in experimental studies
▪️سطوح اندازهگیری از نظر عینیت
– پرسشنامه
– آزمونهای مداد کاغذی نوروپسیکولوژیک
– آزمونها (تکالیف) کامپیوتری سایکوفیزیک
– فیزیولوژیک مانند (ERP)
Rational for QEEG/ERP
▪️ Brain-behavior relationship
منطقی برای QEEG/ERP
▪️ رابطه مغز و رفتار
Origin of behaviour
Behavior: Normal or Abnormal
Language, Emotions, Thoughts, Inhibition
خاستگاه رفتار
رفتار: عادی یا غیر طبیعی
زبان، عواطف، افکار، بازداری
Origin of behaviour
Behavior: Normal or Abnormal
Language, Emotions, Thoughts, Inhibition
Rational for QEEG
Brain activities
fNIRS
fMRI
EEG/ERP/QEEG
MEG Behavior: Normal or Abnormal
Language, Emotions, Thoughts, Inhibition
فعالیتهای مغز
طیف سنج مادون قرمز نزدیک
افامآرآی یا تصویرسازی تشدید مغناطیسی کارکردی
نوار مغز یا الکتروانسفالوگرام/پتانسیل وابسته به رخداد/الکتروانسفالوگرام کمی
Rational for QEEG
Rational for QEEG
Rational for QEEG
Rational for QEEG
Rational for QEEG
Electroencephalography (EEG)
Why EEG became subspeciality of the field of neurology?
EEG abnormalities correlate with epilepsy, tumors, stroke syndromes.
الکتروانسفالوگرافی (EEG)
چرا EEG به فوق تخصص رشته نورولوژی تبدیل شد؟ ناهنجاری های EEG با صرع، تومورها، سندرم های سکته مرتبط است.
Rational for QEEG
Rational for QEEG/ERP
EEG and Behavior relationship
رابطه EEG و رفتار
Rational for ERP
EEG and Behavior relationship
EEG and Behavior: Correlation
EEG و رفتار: همبستگی
Rational for QEEG
Rational for ERP
Rational for QEEG
Clinical Neurophysiology 112 (2001) 2224-2232
www.elsevier.com/locate/clinph
Electrophysiological correlates for response inhibition in a Go/NoGo task
Hirokazu Bokura*, Shuhei Yamaguchi, Shotai Kobayashi
Department of Internal Medicine III, Shimane Medical University, 89-1, Enya, Izumo, Shimane, 693-8501, Japan Accepted 13 September 2001
همبستگی های الکتروفیزیولوژیکی برای مهار پاسخ در یک تکلیف Go/NoGo
Rational for ERP
ERP as a suitable tool in studying of discrete information processing
Rational for ERP
Information processing
Rational for ERP
Information processing
Integrated Visual and Auditory
تست IVA یک آزمون تخصصی جهت ارزیابی توجه و تمرکز و بررسی عملکرد کنترل تکانش در دو حیطه دیداری و شنیداری است. این آزمون برای ایجاد تمایز بین افراد مبتلا به اختلال بیش فعالی و نقص توجه از افراد مبتلا به اختلال سلوک و افراد بدون مشکل طراحی شده است.
Attention deficit hyperactivity disorder (ADHD)
Rational for ERP
Information processing
Rational for ERP
Information processing
Rational for ERP
Information processing
Rational for ERP
Information processing
Rational for ERP
Information processing
Rational for ERP
Information processing
Rational for ERP
Information processing
Rational for ERP
Information processing
Rational for ERP
Electroencephalography (EEG)
Electroencephalography (EEG)
Synaptic activity: EPSP
► FIGURE 6.20
The coexistence of NMDA and AMPA receptors in the postsynaptic membrane of a CNS synapse. (a) An action potential arriving in the presynaptic ter- minal causes the release of glutamate. (b) Glutamate binds to AMPA receptor channels and NMDA recep- tor channels in the postsynaptic membrane. (c) The entry of Na* through the AMPA channels, and Na+ and Ca2+ through the NMDA channels, causes an EPSP.
Neuroscience Exploring_the_Brain Bear and et all
Electroencephalography (EEG)
Synaptic activity: IPSP
A FIGURE 5.16
The generation of an IPSP. (a) An action potential arriving in the presynaptic terminal causes the release of neurotransmitter. (b) The molecules bind to transmitter-gated ion channels in the postsynaptic membrane. If CI enters the postsynaptic cell through the open channels, the membrane will become hyper- polarized. (c) The resulting change in membrane potential (V), as recorded by at microelectrode in the cell, is the IPSP
Neuroscience_Exploring_the_Brain Bear and et all
Electroencephalography (EEG)
Neuronal geometry and architecture
Parallel configuration
Pyramidal neurons are spatially aligned] perpendicular to the cortical surface.
Creates a dipole layer or dipole sheet in the cortex.
Thus, EEG represents mainly the postsynaptic potentials of pyramidal
¡neurons close to the
recording electrode
• Excitatory input to layer I generates an EPSP in apical dendrites and an active sink.
A passive source is generated at the soma resulting in current flowing toward layer I.
⚫ Results in the EEG recording a negative potential at the location above the neurons.
Excitatory thalamic input to basal dendrites in layer IV results in EPSP and an extracellular sink.
• A passive source is
generated at the apical dendrites and current flows toward cell body.
Generated positive potential at the surface.
Basic Neurophysiology and the Cortical Basis of EEG, Gregory L. Holmes and Roustem Khazipov
Electroencephalography (EEG)
Electroencephalography (EEG)
Electric field
Dipoles are created when current flows between a source and sink that are separated in space.
Source place where current flows from
Sink – place where current flows to
www.ccs.fau.edu
Electroencephalography (EEG)
Focus of attention
EEG features:
Frequency, Amplitude, Phase
EEG features: Frequency
Hertz (Hz): Frequency/Speed of the wave per second
EEG features: Frequency
Brain Wave Frequencies
Delta (1-4 Hz)
Theta (4-8 Hz)
Alpha (8-12 Hz)
Beta (12-36 Hz)
Gamma (36+ Hz)
EEG features: Amplitude
EEG features: Superimposition
“A superimposed signal can be made by adding two or more sinusoidal signals with different frequencies
Generation of a superimposed EEG
EEG Recording Purpose?
to qualitative
Qualitative (Conventional, Standard)
☐ Quantitative
Quantitative EEG (QEEG) analysis techniques can provide additional measurements using computers and algorithms such as Fast Fourier Transformation (FFT).
EEG Recording Purpose?
to qualitative
Qualitative (Conventional, Standard)
☐ Quantitative
Quantitative EEG (QEEG) analysis techniques can provide additional measurements using computers and algorithms such as Fast Fourier Transformation (FFT).
Quantitative
Electroencephalography
Methods
☐ Frequancy domain:
– Spectral analysis
☐ Temporal domain:
– Event-Related potentiels (ERP)
– Event-Related Desynchronization/Synchronization (ERD/ERS)
☐ Spatial domain:
– Brain mapping
☐ Phase space:
– Chaos theory
– Fractal theory
Quantitative
Electroencephalography
Methods
☐ Temporal domain:
– Event-Related potentiels (ERP)
– Event-Related Desynchronization/Synchronization (ERD/ERS)
Temporal domain
Event-Related Potentiels (ERP)
☐ Brain electrical activity that comes from simultaneous firing of synapses, and is related to a specific event.
Temporal domain
Event-Related Potential (ERP)
☐ How do you measure them?
ERP Recording
EEG recording for Temporal domain
EEG Recording
EEG recording for Temporal domain
Event-Related Potential (ERP)
Waveform analysis
EEG Recording
EEG recording for Temporal domain
Event-Related Potential (ERP)
Temporal domain
Event-Related Potentials (ERP)
Temporal domain
Event-Related Potentials (ERP)
Time-locked activity and extraction by averaging
Ongoing activity reflects “noise” ☐ Activity that reflects processing of a given stimulus “signal”
☐ The signal-related activity can be extracted because it is time-locked to the presentation of the stimulus
Importance of Clean Data
IaRPs
ERPs are tiny
-Many experimental effects are less than a millionth of a volt
☐ ERPS are embedded in noise that is 20- 100 μV
☐ Averaging is a key method to reduce noise
Importance of Clean Data
Just having a lot of trials is often not enough to get clean data
☐ Cleaning up noise after recording has a cost
– Filters distort the ERPS
Importance of Clean Data
Treatments always have side effects
Importance of Clean Data
Treatments always have side effects
ERP Components
Most commonly label peaks and troughs.by polarity (P or N) and latency at active recording site
☐ Quantifying
– Amplitude
Latency
Area
ERP Components
Most commonly label peaks and troughs by polarity (P or N) and latency at active recording site
☐ Quantifying
– Amplitude
Latency
Area
ERP Components
Most commonly label peaks and troughs by polarity (P or N) and latency at active recording site
☐ Quantifying
Amplitude
Latency
Area
ERP Components
Most commonly label peaks and troughs.by polarity (P or N) and latency at active recording site
☐ Quantifying
Amplitude
Latency
Area
ERP Components
Most commonly label peaks and troughs.by polarity (P or N) and latency at active recording site
☐ Quantifying
Amplitude
Latency
Area
Measuring ERP Amplitudes
Basic options
Peak amplitude
Or local peak amplitude
Mean/area amplitude
ERP Components
Most commonly label peaks and troughs.by polarity (P or N) and latency at active
recording site
☐ Quantifying
Amplitude
Latency
Area
Plotting- The Right Way
Peaks and Components
ERP waveform contains several peaks People typically assume that each peak corresponds to a single underlying “latent” component
Very Early Components
Waves I-VI represent evoked activity in auditory pathways and nuclei of the brainstem
Early Components
Early components <60-150 msec
occur in obligatory fashion
are called Exogenous determined “outside” organism
Later ERP components
Later ERP components
Highly sensitive to changes in – State of organism
Meaning of stimulus (NOT physical characteristics
Information processing demands of task
☐ Therefore termed Endogenous = determined within organism
Not all components fit neatly into exogenous or endogenous categories
☐ Both Obligatory but modulated by psychological factors
Pre-Processing
۱- Filtering
۲- Artifact Correction by means of ICA
Eye Movement
۳- Artifact Rejection
۴- Error response removing
M. A. NAZARI
Ph.D in Neuroscience
Professor, Iran University of Medicl Sciences
