A new technique for the analysis of background and evoked EEG activity: time and amplitude distributions of the EEG deflections

Rodionov, Vladimir; Goodman, Craig; Fisher, Larry; Rosenstein, Gershom Zvi; Sohmer, Haim

doi:10.1016/s1388-2457(02)00199-2

Cited by 10 publications

(8 citation statements)

References 12 publications

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“…Although fewer in number, aberrant responses were found in all subjects, both normal controls and schizophrenia patients. Previous studies have regarded these responses as noncontributing, nonresponsive, or inappropriate [6], [14]. However, we showed that they play a crucial role in determining the amplitude of the ensemble average response, which is the one most widely used feature in the EP clinical literature.…”

Section: Discussionmentioning

confidence: 76%

Aberrant auditory evoked responses in schizophrenia: Evidence from single-trial analysis

Iyer

Boutros

Zouridakis

2011

2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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The average N100 (a negative response occurring around 100 ms poststimulus) component of the auditory evoked potential (EP) has been recently used in the study of schizophrenia. Averaging, however, eliminates all temporal variability of the recorded signals and, therefore, hampers the exploration of the temporal dynamics underlying the generation of the N100 component. In this study, we analyzed EPs on a single-trial basis using an iterative independent component analysis procedure that is capable of extracting individual components out of an entire EP waveform. This approach allowed estimation of an N100 in each single trial and measurement of its morphological features such as polarity, which could be either negative (most frequently) or positive (less frequently). In the latter case, the N100 component was termed aberrant. We analyzed responses from 23 normal controls (NC) and 15 schizophrenia (SZ) patients in a paired stimulus paradigm, where a first stimulus S(1) was followed by a second one S(2) 0.5 s later. To compare N100 responses within and across the two subject groups, we defined a negative polarity index NPI as the percentage of single trials that had a negative polarity N100. Our results show significantly higher NPI values in NC compared to SZ, for both the S(1) and S(2) responses. Additionally, the difference in NPI values between the S(1) and S(2) responses was significant in NC but not in SZ. We conclude that both normal and schizophrenia subjects exhibit aberrant N100 responses, but these events are more frequent in the SZ patient group. The higher number of aberrant responses can explain the lower amplitude EPs typically observed in schizophrenia, and may be one of the factors contributing to sensory gating deficits consistently reported in these patients.

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Section: Discussionmentioning

confidence: 76%

Aberrant auditory evoked responses in schizophrenia: Evidence from single-trial analysis

Iyer

Boutros

Zouridakis

2011

2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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“…In this context, post-stimulus activity is considered to be a mixture of stimulus-related and spontaneous EEG activity. It is also possible that not all stimuli produce a response (Ford et al, 1994; Wagner et al, 2000; Rodionov et al, 2002), which would give rise to underestimating the magnitude of the response.…”

Section: Introductionmentioning

confidence: 99%

Evoked potential variability

Boutros

Jansen

2009

Journal of Neuroscience Methods

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An unsupervised correlation-based clustering method was developed to assess the trial-to-trial variability of auditory evoked potentials (AEPs). The method first decomposes single trials into three frequency bands, each containing activity primarily associated with one of the three major AEP components, i.e., P50, N100 and P200. Next, single-trial evoked potentials with similar post-stimulus characteristics are clustered and selectively averaged to determine the presence or absence of an AEP component. The method was evaluated on actual AEP and spontaneous EEG data collected from 25 healthy participants using a paradigm in which pairs of identical tones were presented, with the first stimulus (S1) presented 0.5 s before the second stimulus (S2). Homogeneous, well-separated clusters were obtained and substantial AEP variability was found. Also, there was a trend for S2 to produce fewer ‘complete’ (and significantly smaller) responses than S1. Tests conducted on spontaneous EEG produced similar clusters as obtained from EP data, but significantly fewer stimuli produced responses containing all three EP components than seen in AEP data. These findings suggest that the clustering method presented here performs adequately to assess trial-to-trial EP variability. Also, the results suggest that the sensory gating observed in normal controls may be caused by the fact that the second stimulus generates fewer ‘responsive’ trials than the first stimulus, thus resulting in smaller ensemble averages.

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“…Previous studies have regarded these responses as noncontributing, nonresponsive, or inappropriate [70,71].…”

Section: Discussionmentioning

confidence: 99%

Schizophrenia Assessment Using Single-Trial Analysis of Brain Activity

Zouridakis

Iyer

Díaz

2013

Modern Electroencephalographic Assessment Techniques

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In the quest for neurophysiological biomarkers that uniquely characterize schizophrenia subjects, auditory evoked potentials (EPs) have been extensively used during the past several decades. Typically, EPs are estimated using ensemble averaging to obtain robust components. Averaging, however, eliminates all temporal variability of the recorded signals and, therefore, hampers the study of the brain temporal dynamics underlying the generation of EP components. In this chapter, we present a methodology for analyzing EPs on a single-trial basis using an iterative independent component analysis procedure. The method is capable of identifying and measuring the amplitude, latency, and overall morphology of individual EP components in single trials and, as such, permits the study of phase characteristics among single trials while preserving known features of the average EPs. Recordings from schizophrenia patients and normal controls demonstrate that activity phase synchronization plays a crucial role in EP generation and explains the sensory gating deficits observed in schizophrenia subjects. Furthermore, the findings from this method are very robust across recordings from different labs and experimental protocols and can be used to separate schizophrenia patients from normal controls with 100 % classification accuracy.

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A new technique for the analysis of background and evoked EEG activity: time and amplitude distributions of the EEG deflections

Cited by 10 publications

References 12 publications

Aberrant auditory evoked responses in schizophrenia: Evidence from single-trial analysis

Aberrant auditory evoked responses in schizophrenia: Evidence from single-trial analysis

Evoked potential variability

Schizophrenia Assessment Using Single-Trial Analysis of Brain Activity

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