Eeg Eog
Eeg Eog
Eeg Eog
intracellular
recording extracellular
recording
In normal subjects the raw EEG can be filtered for four
frequency bands: alpha, beta, theta and delta waves.
BETA
ALPHA
THETA
DELTA
Brain waves characteristics
Brain Appearance Voltage (uV) Frequency Distribution
waves ( Hz)
In all normal,
adult persons,
when they are Occurs most
alpha relaxed, awake in
a quiet, resting 20-100 7-13 intensely in the
occipital and
state, without parietal regions.
visual sensation
(i.e. closed eyes)
During the
activation of the Occurs mostly in
beta CNS (replaces the
5-10 13-27 the frontal
alpha waves after region.
opening the eyes
in bright light).
Brain waves characteristics
-It is normal in
children (2-3
years)
delta - In adults in
50-200 0.5-4 - in all
deep sleep regions
Uses of EEG
diagnosis of epilepsy
Awake
Stage 1
Stage 2
Stage 3
Stage 4
Time (hours)
Sleep stages and types
Recording technique
-Electrodes are placed on the scalp. The scalp must be degreased with
alcohol.
-The connections with the electroencephalograph are made (with
electric wires)
-The recordings are made in a quiet room, in resting state, awake,
with and without visual sensations (closed eyes).
- Recording with activation-stimulation of the central nervous system
are made by: opening the eyes in bright light, intermittent light
stimulation, acoustic stimulation
Practical work
Recording EEG
EOG
Background :
One of the most important functions our eyes can perform is to fix or lock
on a specific region in our field of vision. There are two primary
mechanism used to track objects in our visual field: voluntary tracking
and involuntary tracking. The voluntary fixation allows us to move our
eyes in any directions we wish, and involuntary fixation allows us to track
an object in our visual field once it has been found.