EEG (electroencephalogram)

-


An electroencephalogram (EEG) is a painless procedure that uses small, flat metal discs (electrodes) attached to scalp to detect electrical activity in brain. Brain cells communicate via electrical impulses and are active all the time, even when we asleep. This activity shows up as wavy lines on an EEG recording.

An EEG is one of the main diagnostic tests for epilepsy. An EEG may also play a role in diagnosing other brain disorders.

Wave patterns

Delta waves.


  • Delta is the frequency range up to 4 Hz. It tends to be the highest in amplitude and the slowest waves. It is seen normally in adults in slow wave sleep. It is also seen normally in babies.


Theta waves.


  • Theta is the frequency range from 4 Hz to 7 Hz. Theta is seen normally in young children. Excess theta for age represents abnormal activity. On the contrary this range has been associated with reports of relaxed, meditative, and creative states.


Alpha waves.



  • Alpha is the frequency range from 7 Hz to 14 Hz. Hans Berger named the first rhythmic EEG activity he saw as the "alpha wave". It emerges with closing of the eyes and with relaxation, and attenuates with eye opening or mental exertion.


Beta waves.



Beta is the frequency range from 15 Hz to about 30 Hz. It is seen usually on both sides in symmetrical distribution and is most evident frontally. Beta activity is closely linked to motor behavior and is generally attenuated during active movements. Low amplitude beta with multiple and varying frequencies is often associated with active, busy or anxious thinking and active concentration. alert or anxious or who have their eyes open.


Gamma waves.



Gamma is the frequency range approximately 30–100 Hz. Gamma rhythms are thought to represent binding of different populations of neurons together into a network for the purpose of carrying out a certain cognitive or motor function.


Comments

Post a Comment

Popular posts from this blog

Challenging obstacles for immigrants

-
Image
Many people immigrate every year, towards developed country (USA, Canada, Australia, UK etc.)   to get a better life. As a highly developed country, they can be the best choice for the immigrants from all around the world and can offer a high standard life to them. However, immigrants face various difficulties during the first years of their entrance in to the developed country . Language barrier, finding a job and the cultural differences are the most common challenges.  Language barrier is the first challenge for the immigrants. It will be very hard for them to communicate with others. Even though most of immigrants spend lots of time and money to learn English before moving to developed country, it will not be very easy for them to use their language skills in every day’s life. Since developed country, has a divers population, it will be hard for the immigrants to understand the different accents of native speakers. Also it takes a long time to learn all th...
Read more

What is Linux Shell?

-
Image
  What is Linux Shell? In Linux and Unix, a shell refers to a program that is used to interpret the typed commands the user sends to the operating system.  The closest analogy in windows is  MS-DOS, Shell name is COMMAND.COM which is also used for same purpose, but it's not as powerful as our Linux Shells are! Computer understand the language of 0's and 1's called binary language. In early days of computing, instruction are provided using binary language, which is difficult for all of us, to read and write. So in OS there is special program called Shell. Shell accepts your instruction or commands in English (mostly) and if its a valid command, it is pass to kernel.   Shell is a user program or it's environment provided for user interaction. Shell is an command language interpreter that executes commands read from the standard input device (keyboard) or from a file. Shell is not part of system kernel, but uses the system kernel to execute pr...
Read more

Permission and Ownership using awk

-
Image
Awk programming The easiest way to learn the awk command usage is to see them in action. In order to find the working directory we are in . Type pwd ( "print working directory" ) Then type ls ( listing)for listing to see what's in the current directory $ ls Permissions and Ownership List directories and files ls -al # shows something like this for each file/dir: drwxrwxrwx # d: directory # rwx: read write execute # first triplet: user permissions (u) # second triplet: group permissions (g) # third triplet: world permissions (o)     It shows like this when we type   $ls -al   drwxr-xr-x 2 prakash prakash 4096 Oct 27 03:56 Videos drwxr-xr-x 2 prakash prakash 4096 Nov 18 10:19 .vim -rw------- 1 prakash prakash 11158 Dec 16 18:54 .viminfo -rw------- 1 prakash prakash 124 Dec 16 18:11 .Xauthority -rw------- 1 prakash prakash 82 Dec 16 18:11 .xsession-errors Assign write and execute permission...
Read more