Neural Network Reorganization Analysis During an Auditory Oddball Task in Schizophrenia Using Wavelet Entropy

Abstract

Abstract:The aim of the present study was to characterize the neural network reorganization during a cognitive task in schizophrenia (SCH) by means of wavelet entropy (WE). Previous studies suggest that the cognitive impairment in patients with SCH could be related to the disrupted integrative functions of neural circuits. Nevertheless, further characterization of this effect is needed, especially in the time-frequency domain. This characterization is sensitive to fast neuronal dynamics and their synchronization that may be an important component of distributed neuronal interactions; especially in light of the disconnection hypothesis for SCH and its electrophysiological correlates. In this work, the irregularity dynamics elicited by an auditory oddball paradigm were analyzed through synchronized-averaging (SA) and single-trial (ST) analyses. They provide complementary information on the spatial patterns involved in the neural network reorganization. Our results from 20 healthy controls and 20 SCH patients showed a WE decrease from baseline to response both in controls and SCH subjects. These changes were significantly more OPEN ACCESSEntropy 2015, 17 5242 pronounced for healthy controls after ST analysis, mainly in central and frontopolar areas. On the other hand, SA analysis showed more widespread spatial differences than ST results. These findings suggest that the activation response is weakly phase-locked to stimulus onset in SCH and related to the default mode and salience networks. Furthermore, the less pronounced changes in WE from baseline to response for SCH patients suggest an impaired ability to reorganize neural dynamics during an oddball task.

Novel measure of the weigh distribution balance on the brain network: Graph complexity applied to schizophrenia

“…Furthermore, low frequencies, like theta band, are related to long-range interactions [20]. Consequently, the deficit on the activation response of long-range interactions might contribute to the pathological process [3]. Hence, SCH can be linked with an abnormal network reorganization of the neural substrates responsible of the P3a generation.…”

“…Continuous Wavelet Transform (CWT) provides an alternative to classical Fourier analyses. In the present study, the complex Morlet wavelet was chosen as "mother wavelet", since it provides a biologically plausible fit to the ERP signals [3]. Thus, the Wavelet Scalogram (WS) was computed from the CWT of each trial [13].…”

Exploring non-stationarity patterns in schizophrenia: neural reorganization abnormalities in the alpha band

“…Participants underwent a threestimulus auditory oddball task. Tones (duration 50 ms, rise and fall time 5 ms, intensity 90 dB and inter-stimulus interval randomly ranged between 1.16-1.40 s [6]) were presented to participants in random 600 tone series. These consisted of target (500 Hz), distractor (1000 Hz), and standard (2000 Hz) tones, with probabilities of 0.20, 0.20, and 0.60 respectively.…”

“…Several methods have been used to analyze transient dynamics in neural activity during an auditory oddball task or during resting-state. Such measures, of a time-dependent nature, include wavelet entropy [6,13], multiscale entropy [14], median frequency [12,15] and relative power (RP) [15], among others. Many of these studies have found widespread lower neural reorganization (i.e., transient dynamical reorganization of brain activity during an attentional process) for SCH subjects compared to controls during the active task response [6,12,15].…”

“…Electroencephalography (EEG) recordings have been used to analyze neural processing in SCH through the analysis of event-related potentials (ERPs) [4][5][6][7]. EEG captures the summation of neural oscillations in the brain and their synchronization [8].…”