Marissa Westerfield

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This review discusses the theory and practical application of independent component analysis (ICA) to multi-channel EEG data. We use examples from an audiovisual attention-shifting task performed by young and old subjects to illustrate the power of ICA to resolve subtle differences between evoked responses in the two age groups. Preliminary analysis of(More)
Scalp-recorded electroencephalographic (EEG) signals produced by partial synchronization of cortical field activity mix locally synchronous electrical activities of many cortical areas. Analysis of event-related EEG signals typically assumes that poststimulus potentials emerge out of a flat baseline. Signals associated with a particular type of cognitive(More)
This study investigated the functional neuroanatomical correlates of spatial attention impairments in autism spectrum disorders (ASD) using an event-related functional magnetic resonance imaging (FMRI) design. Eight ASD participants and 8 normal comparison (NC) participants were tested with a task that required stimulus discrimination following a spatial(More)
After visual target stimuli presented infrequently at a covertly attended location, quicker speeded button presses immediately followed a larger positive (P3f) ramp in averaged electroencephalographic (EEG) recordings from the forehead. We show this peak in the mean response time locked to the button press to be principally composed of triphasic, primarily(More)
We examine the problem of accurate detection and classification of artifacts in continuous EEG recordings. Manual identification of artifacts, by means of an expert or panel of experts, can be tedious, time-consuming and infeasible for large datasets. We use autoregressive (AR) models for feature extraction and characterization of EEG signals containing(More)
Single-trials in event-related potential (ERP) experiments consists of electroencephalographic (EEG) recordings of brain activity time-locked to experimental events. These are usually averaged across a set of similar or identical events to increase their signal/noise ratio relative to non-phase locked EEG activity and non-brain artifacts, regardless of the(More)
Event-related potentials (ERPs), are portions of electroencephalographic (EEG) recordings that are both timeand phase-locked to experimental events. ERPs are usually averaged to increase their signal/noise ratio relative to non-phase locked EEG activity, regardless of the fact that response activity in single epochs may vary widely in time course and scalp(More)
We recorded visual event-related brain potentials from 32 adult male participants (16 high-functioning participants diagnosed with autism spectrum disorder (ASD) and 16 control participants, ranging in age from 18 to 53 years) during a three-stimulus oddball paradigm. Target and non-target stimulus probability was varied across three probability conditions,(More)
The EEG reflects the activation of large populations of neurons that act in synchrony and propagate to the scalp surface. This activity reflects both the brain's background electrical activity and when the brain is being challenged by a task. Despite strong theoretical and methodological arguments for the use of EEG in understanding the neural correlates of(More)