The document discusses electroencephalography (EEG), which detects electrical activity in the brain using electrodes placed on the scalp. EEG is used to evaluate brain disorders like seizures and sleep disorders. An EEG recording consists of raw brain wave signals that are digitized. Brain waves are categorized by frequency into different types like delta, theta, alpha and beta waves that correspond to different mental states. The 10-20 system is commonly used for electrode placement on the brain lobes and hemispheres. EEG helps diagnose conditions like major depressive disorder that affects mood and daily functioning.

1. Electroencephalography (EEG)
Dr. Amit M. Joshi
Assistant Professor
Department of Electronics &
Communication

2. ELECTROENCEPHALOGRAM (EEG)
❏ EEG is a medical test that detects abnormalities
in brain waves, or in the electrical activity of
our brain.
❏ EEG is used to evaluate several types of brain
disorders, such as, seizures, autisum,
depression, Alzheimer, sleep disorders, etc.
❏ An EEG file consists of raw signals, which are
the digitized version of the electrical potential
between the electrode and the reference point.
❏ EEG signal frequency range is 0.1 Hz to 100 Hz

3. CAPTURING OF BRAIN WAVES THROUGH EEG
❏ Electrodes, consisting of small metal discs with
thin wire are posted on the scalp.
❏ The electrical activity of brain ranges typically
from 10 to 150 micro Volt.
❏ Tiny detected electrical charges from the brain
during various activity is amplified and shown
as a graph on the computer screen.
❏ Brain is divided into two hemisphere: Left &
Right Hemisphere
❏ Each hemisphere has four lobes: Frontal,
Temporal, Parietal and Occipital lobes

4. Lobes of Human Brain
Frontal Lobe:
● Frontal lobe is the largest lobe which is located at the forehead.
● It is also concerned with planning, organizing, problem-solving, memory,
impulse control, decision making, selective attention, controlling behaviour &
emotion.
Temporal lobe
● located on the sides of the brain under the parietal and behind the frontal lobe
● Responsible for sound, speech and memory
● It create hearing and sensory part like touching, smelling

5. Lobes of Human Brain
Occipital Lobe:
● is paced the lower back of the head
● responsible for perceptual and visual information
Temporal lobe
● located which integrates sensory information from different body part
● to understand the things, capturing the data

6. EEG Device
● Comprises of electrodes, conductive gel, amplifiers, and ADC
● Electrodes are placed at brain scalp with conducting gel (Ag-Cl)
● Multi channel device with a wearable cap

7. PHYSICAL PLACEMENT OF ELECTRODES
Physical Placement of electrodes
includes,
❏ Number of channels to be collected
❏ Location of electrodes on scalp
❏ Reference Electrode
Each electrode is evenly distributed on the
scalp.
Most Commonly used electrode
configuration is 10/20 configuration.
Total no.channels- 20 to 21

8. CHANNEL LABELS
The nomenclature of electrodes in generally based on their physical
placement on one’s scalp.
❏ Fp - Prefrontal
❏ F - Frontal
❏ T - Temporal
❏ C - Central
❏ P - Parietal
❏ O - Occipital
❏ A - Mastoid Process (bone near the outer ear)
Even-numbered electrodes are located in the right hemisphere
of the brain while odd-numbered in the left hemisphere.
Positioning of electrodes is referred to as montages as
Referential and bipolar electrodes

9. TYPES OF EEG WAVES
❏ Gamma wave: 3Hz to
100Hz
❏ Beta wave: 13Hz to 30Hz
❏ Alpha wave: 8Hz to 13Hz
❏ Theta wave: 4Hz to 7Hz
❏ Delta wave : <3.5Hz
Theta and Delta waves are
often regarded as slow waves.

10. EEG Wave Types
Delta Wave
• Highest in amplitude and slowest wave
• Sleep and dreaming
Theta Wave
• Records subconscious activities
• observed during deep relaxation and meditation

11. EEG Wave Types
Alpha Wave
• Occurs both sides of the brain with closed eyes
• Awake but relaxed with closed eyes
• Mental disorder detection
Beta Wave
• Related to behaviour and actions
• Busy and active state of mind (talking, running)
Gamma Wave
• perception and consciousness
• Hyper alternateness

12. Brain wave frequency and characteristics

14. MAJOR DEPRESSIVE DISORDER
❏ Depression is a mood disorder that causes a persistent feeling of sadness and
loss of interest. It also goes by the name of Major Depressive Disorder.
❏ It is characterized by lack of motivation, difficult to experience pleasure,
impacting on daily lives activities and in extreme cases, leads to suicide.
❏ According to WHO, almost 5% of adults and 5.7% of adults over 60 years
suffer from depression. Women are more prone to depression than men.
❏ Approximately 280 million people in the world have depression.
❏ Despite of advanced medication and treatment, 75% of people from low and
middle class household receive no treatment.

17. THANK YOU