Evoked potential variability

Hu, Lingli; Boutros, Nash N.; Jansen, Ben H.

doi:10.1016/j.jneumeth.2008.11.021

Cited by 14 publications

(14 citation statements)

References 41 publications

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“…These findings are also consistent with other N100 studies that looked at activity phase synchronization to show population differences [6], [10], [11].…”

Section: Discussionsupporting

confidence: 92%

“…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: 78%

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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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“…These findings are also consistent with other N100 studies that looked at activity phase synchronization to show population differences [6], [10], [11].…”

Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 78%

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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show abstract

“…In general, schizophrenia subjects have a significantly higher number of aberrant responses compared to normal controls, and this can explain both the lower S1 amplitude and the decreased S2 attenuation seen in the patients. These findings are also consistent with other N100 studies that looked at activity phase synchronization to show population differences [15,70,72].…”

Section: Discussionsupporting

confidence: 91%

“…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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“…Nonlinear interactions between stimulus and ongoing activity can result in nonstationary background activity, and the evoked response itself can vary from trial to trial. Thus the residual is a combination of both components due to processes commonly ascribed to induced components, e.g., reorganization of ongoing activity and indirect triggering of oscillatory responses, as well as contributions due to trial-by-trial variability in amplitude and timing of the evoked response (David et al 2006;Hu et al 2009;Truccolo et al 2002). Top-down processes that are reliably elicited by sensory stimuli will also appear in the evoked response (Picton 1992).…”

mentioning

confidence: 99%