Basic of EEG and their applications

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