Ocular artifacts in recording EEGs and event-related potentials II: Source dipoles and source components

Lins, Otávio Gomes; Picton, Terence W.; Berg, Patrick; Scherg, Michael

doi:10.1007/bf01234128

Cited by 212 publications

(134 citation statements)

References 18 publications

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“…Two participants were removed from the analysis due to noisy electrodes. The average HEOG signals for the remaining participants showed a difference of 0.35 uv between percepts (1) and (2), confirming that participants did not systematically move their eyes toward either the perceived front or back of the object (at most a small fraction of a degree; Hillyard and Galambos, 1970;Lins et al, 1993). The EEG data were epoched within a response-locked time window spanning 2 s before and 2 s after the report of a perceptual change, and baseline corrected to the 200 ms prestimulus period.…”

Section: Methodsmentioning

confidence: 76%

“…For the remaining participants, no trials were rejected. The average HEOG (horizontal EOG) signals for the remaining participants showed a difference of 1.08 V between percepts (1) and (2), confirming that participants did not systematically move their eyes toward either the perceived front or back of the object (at most a small fraction of a degree; Hillyard and Galambos, 1970;Lins et al, 1993).…”

Section: Methodsmentioning

confidence: 77%

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The Head of the Table: Marking the “Front” of An Object Is Tightly Linked with Selection

Xu¹,

Franconeri²

2012

J. Neurosci.

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Objects in the world do not have a surface that can be objectively labeled the "front." We impose this designation on one surface of an object according to several cues, including which surface is associated with the most task-relevant information or the direction of motion of an object. However, when these cues are competing, weak, or absent, we can also flexibly assign one surface as the front. One possibility is that this assignment is guided by the location of the "spotlight" of selection, where the selected region becomes the front. Here we used an electrophysiological correlate to show a direct temporal link between object structure assignments and the spatial locus of selection. We found that when human participants viewed a shape whose front and back surfaces were ambiguous, seeing a given surface as front was associated with selectively attending to that location. In Experiment 1, this pattern occurred during directed rapid (every 1 s) switches in structural percepts. In Experiment 2, this pattern occurred during spontaneous reversals, from 900 ms before to 600 ms after the reported percept. These results suggest that the distribution of selective attention might guide the organization of object structure.

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Section: Methodsmentioning

confidence: 76%

Section: Methodsmentioning

confidence: 77%

The Head of the Table: Marking the “Front” of An Object Is Tightly Linked with Selection

Xu¹,

Franconeri²

2012

J. Neurosci.

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“…First, it can distort the regression equation used to calculate the EOG propagation factors. This distortion can be decreased by subtracting any stimulus-synchronized contribution~e.g., Gratton et al, 1983!, by low-pass filtering the recording or by averaging the recordings using the onset of the eye-movement for synchronization~Lins, Picton, Berg, & Scherg, 1993b!. Second, multiplying the EOG recording by the propagation factors and then subtracting this scaled waveform from the scalp EEG recording will remove a portion of the frontal EEG signal as well as the EOG.…”

Section: (Iv) Artifact Compensation Procedures Must Be Documented Clementioning

confidence: 99%

Guidelines for using human event-related potentials to study cognition: Recording standards and publication criteria

et al. 2000

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Event-related potentials~ERPs! recorded from the human scalp can provide important information about how the human brain normally processes information and about how this processing may go awry in neurological or psychiatric disorders. Scientists using or studying ERPs must strive to overcome the many technical problems that can occur in the recording and analysis of these potentials. The methods and the results of these ERP studies must be published in a way that allows other scientists to understand exactly what was done so that they can, if necessary, replicate the experiments. The data must then be analyzed and presented in a way that allows different studies to be compared readily. This paper presents guidelines for recording ERPs and criteria for publishing the results.Descriptors: Event-related potentials, Methods, Artifacts, Measurement, Statistics Event-related potentials~ERPs! are voltage fluctuations that are associated in time with some physical or mental occurrence. These potentials can be recorded from the human scalp and extracted from the ongoing electroencephalogram~EEG! by means of filtering and signal averaging. Although ERPs can be evaluated in both frequency and time domains, these particular guidelines are concerned with ERPs recorded in the time domain, that is, as waveforms that plot the change in voltage as a function of time. These waveforms contain components that span a continuum between the exogenous potentials~obligatory responses determined by the physical characteristics of the eliciting event in the external world! and the endogenous potentials~manifestations of information processing in the brain that may or may not be invoked by the eliciting event!.1 Because the temporal resolution of these measurements is on the order of milliseconds, ERPs can accurately measure when processing activities take place in the human brain. The spatial resolution of ERP measurements is limited both by theory and by our present technology, but multichannel recordings can allow us to estimate the intracerebral locations of these cerebral processes. The temporal and spatial information provided by ERPs may be used in many different research programs, with goals that range from understanding how the brain implements the mind to making specific diagnoses in medicine or psychology. Data cannot have scientific value unless they are published for evaluation and replication by other scientists. These ERP guidelines are therefore phrased primarily in terms of publication criteria. The scientific endeavor consists of three main steps, and these map well onto the sections of the published paper. The first step is the most important but the least well understood-the discovery of Address reprint requests to: Terence W. Picton, Rotman Research Institute,

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“…However, PCA cannot completely separate eye artifacts from brain signals, especially when they have comparable amplitudes (Lagerlund et al, 1997;Jung et al, 1998bJung et al, , 2000. By combining PCA, multiple source models for EOG and EEG, and an artifact-aligned averaging method (Lins et al, 1993), Berg and Scherg (1994) demonstrated a more effective PCA-based approach to correct eye artifacts. However, the accuracy of their method depends on the availability of separate and accurate inverse source solutions for EEG and EOG.…”

Section: Introductionmentioning

confidence: 99%

Removal of eye activity artifacts from visual event-related potentials in normal and clinical subjects

Jung¹,

Makeig²,

Westerfield³

et al. 2000

Clinical Neurophysiology

1,208

744

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Objectives: Electrical potentials produced by blinks and eye movements present serious problems for electroencephalographic (EEG) and event-related potential (ERP) data interpretation and analysis, particularly for analysis of data from some clinical populations. Often, all epochs contaminated by large eye artifacts are rejected as unusable, though this may prove unacceptable when blinks and eye movements occur frequently.Methods: Frontal channels are often used as reference signals to regress out eye artifacts, but inevitably portions of relevant EEG signals also appearing in EOG channels are thereby eliminated or mixed into other scalp channels. A generally applicable adaptive method for removing artifacts from EEG records based on blind source separation by independent component analysis (ICA) (Neural Computation 7 (1995) 1129; Neural Computation 10(8) (1998) 2103; Neural Computation 11(2) (1999) 606) overcomes these limitations.Results: Results on EEG data collected from 28 normal controls and 22 clinical subjects performing a visual selective attention task show that ICA can be used to effectively detect, separate and remove ocular artifacts from even strongly contaminated EEG recordings. The results compare favorably to those obtained using rejection or regression methods.Conclusions: The ICA method can preserve ERP contributions from all of the recorded trials and all the recorded data channels, even when none of the single trials are artifact-free. q

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Ocular artifacts in recording EEGs and event-related potentials II: Source dipoles and source components

Cited by 212 publications

References 18 publications

The Head of the Table: Marking the “Front” of An Object Is Tightly Linked with Selection

The Head of the Table: Marking the “Front” of An Object Is Tightly Linked with Selection

Guidelines for using human event-related potentials to study cognition: Recording standards and publication criteria

Removal of eye activity artifacts from visual event-related potentials in normal and clinical subjects

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