Essay On Ocular Artifacts

How ocular artifacts are formed?

Ocular artifacts are formed by any type of movement of eye; this can be explained by the type of the movement of the eyeand even by the blink of an eye.Here, the Front polar (Fp) and Front (F) are the electrodes which placed near or above the ocular region such that, these electrodes are mainly affected with the ocular artifacts. Considering the eye as the dipole which can state as that front part cornea is more positively charged than the retina. This makes the electrode to become more positively charge than the brain potential when the cornea reached near in the eye movement.

Vertical, Horizontal eye movement

When the eye ball moves vertically i.e., up and down, and side to side then the potential from

Here in this case that eye lid act as the sliding electrode and also as a bridge that to connect the scalp to the positively charged cornea. As the eye lid slides over the eye ball that cornea bearing positive charge then eye lid picks up the potential from the positively charged cornea thus, the charge of the cornea potential imposed to the nearby electrode and it become more positive, it makes downward deflection in the EEG graph.

II-Methods for the removal of ocular artifacts

There are many methods proposed that to remove the ocular artifacts from the recordings of the EEG. Here is the study of some methods to eliminate these artifacts

1) Eye Fixation Method.

As the artifacts are formed using the eye ball movements and the eye blinks, it is proposed (Hillyard and Gallambos 1970) that the patient or the subject is asked to stop the movements caused by the eye and can asked to close eyes intentionally. It somehow reduces the artifact but I cannot possible with some subjects like children, mentally illness people who can’t understand. It somehow affects the Contingent Negative Variation (CNV)