Uncovering Gamma in Visual Tasks

Gamma is an important frequency band of the electroencephalogram (EEG), but its study has been impaired by problems with artefacts. This paper focuses on the artefacts caused by contraction of the extra-ocular muscles at the start of a saccade, which produces spurious gamma oscillations in the EEG....

Full description

Saved in:
Bibliographic Details
Published inBrain topography Vol. 23; no. 1; pp. 58 - 71
Main Author Nottage, Judith F
Format Journal Article
LanguageEnglish
Published Boston Boston : Springer US 01.03.2010
Springer US
Springer Nature B.V
Subjects
Algorithms
Biomedical and Life Sciences
Biomedicine
Electroencephalography - methods
Evoked Potentials
Humans
Neurology
Neurosciences
Oculomotor Muscles - physiology
Original Paper
Pilot Projects
Psychiatry
Regression Analysis
Saccades - physiology
Signal Processing, Computer-Assisted
Time Factors
Saccade
Gamma
Spike potential
Power-line
Electroencephalography
Artefact
Online AccessGet full text

Cover

More Information
Summary:Gamma is an important frequency band of the electroencephalogram (EEG), but its study has been impaired by problems with artefacts. This paper focuses on the artefacts caused by contraction of the extra-ocular muscles at the start of a saccade, which produces spurious gamma oscillations in the EEG. An algorithm was written and tested which detects and reduces the effect of this artefact. It involves novel adaptations of standard regression techniques which have traditionally been used to reduce blink artefacts, so as to render them applicable to the gamma band ocular artefact. Before the algorithm can be applied any power-line noise must be removed by noise cancellation and not notch filtering. The sharp, broadband gamma peak at around 200 ms was substantially reduced by the algorithm in all three subjects tested. However, there may be lower amplitude, task related, modulations in gamma which are uncovered when the artefact is reduced. The amplitude of the artefact had its largest positive value at the most anterior electrodes and its largest negative value at midline central and parietal electrodes, and these two sets of locations also showed the greatest reductions in gamma band magnitude after application of the algorithm. This study demonstrates the feasibility of reducing the saccade linked gamma band artefact.
Bibliography:http://dx.doi.org/10.1007/s10548-009-0129-y
ObjectType-Article-1
SourceType-Scholarly Journals-1
content type line 14
ObjectType-Feature-2
content type line 23
ObjectType-Article-2
ObjectType-Undefined-1
ObjectType-Feature-3
ISSN:0896-0267
1573-6792
1573-6792
DOI:10.1007/s10548-009-0129-y