Measuring the capacity for auditory system plasticity: An examination of performance gains during initial exposure to auditory-targeted cognitive training in schizophrenia

Abstract

Auditory-Targeted Cognitive Training (ATCT), which aims to improve auditory information processing efficiency, has shown great promise for remediating cognitive deficits in schizophrenia (SZ). However, there is substantial heterogeneity in the degree of cognitive gains made during ATCT, and some patients show negligible benefit after completing therapeutic doses of training. Identifying individual differences that can be measured early in the course of ATCT and that predict subsequent cognitive benefits from the intervention is therefore important. The present study calculated a variety of performance metrics during the initial hour of exposure to ATCT Sound Sweeps, a frequency discrimination time-order judgment task, and investigated the relationships of these metrics to demographic, clinical, and cognitive characteristics of SZ patients. Thirty-seven SZ outpatients completed measures of auditory attention, working memory, verbal memory, and executive functioning, followed by 1h of Sound Sweeps training. Performance metrics, calculated after the first training level, the first training stage (Levels 1-4), and the entire hour of training included baseline and best auditory processing speed (APS) scores, as well as percent improvement in APS after training. The number of training levels completed by each participant was also calculated. Baseline and best APS correlated with performance in all cognitive domains, whereas APS improvements only correlated with verbal memory. Number of training levels completed was marginally associated with auditory attention only.

Conclusions: Sound Sweeps performance correlates with a range of neurocognitive abilities. APS improvement may provide a particularly sensitive index of "plasticity potential" within the neural network underlying verbal learning and memory.

Keywords: Auditory processing; Cognition; Cognitive remediation; Psychosis; Schizophrenia; Training.

Conflict of interest statement

Dr. Vinogradov is a paid consultant to Brain Plasticity Inc., a company with a commercial interest in cognitive training software. Dr. Swerdlow is a consultant for Genco Sciences, Inc. Dr. Light has served as a consultant for Astellas, Forum, and NeuroVerse for matters unrelated to this study. Drs. Tarasenko, Perez, Braff and Mr. Pianka report no biomedical financial interests or potential conflicts of interest.

Published by Elsevier B.V.

Figures

Figure 1

ATCT performance metrics examined in the present study. Scores represent the duration of sounds in ms that participants were able to discriminate direction of frequency modulation. Panel A represents the “initial” improvement metric, in which baseline (green circle) and best (blue circle) scores from the first level of the first training stage were compared. Panel B illustrates the “composite” improvement metrics, for which baseline and best scores were average across levels that differed by stimulus frequency and ISI and then compared. Two composite metrics were calculated – one from the first stage of training only, and one from all levels completed by participants. Panel C represents the “levels completed” metric, which consisted of the number of levels participants were able to complete during one hour of ATCT.

Figure 2

Data from each investigational ATCT performance metric. A) Performance improvement trajectories for each participant during Level 1, Stage 1, and Hour 1. Black dots represent baseline auditory processing speed (APS) and lines represent APS improvement trajectories. Lower score indicates better performance. B) Histogram of the number of training levels completed by participants during the one-hour training session.

Figure 3

“Medium” and “Large” Correlations Among ATCT Performance Metrics and Cognitive Domains