Effects of rhythmic auditory stimulation on vision: Oscillations in performance can be enhanced, but not induced.

A variety of reports suggest that rhythmic auditory stimulation can entrain visual perception, inducing perceptual oscillations as a function of time relative to the auditory rhythm. These effects have, to date, been reported only for stimulation frequencies at and below 3 Hz. Here we investigate the effects of rhythmic auditory stimulation on the detection of masked visual targets when this stimulation occurs at frequencies to which the visual system has been shown to entrain (8-12 Hz). Across four experiments, we found no consistent evidence of poststimulation modulations in performance induced by 8.5, 10.6, or 12.1 Hz auditory stimulation. This absence of a consistent auditory-to-visual effect was paralleled by an absence of unimodal effects (oscillations in auditory performance) following 12.1 Hz auditory stimulation. In a fifth experiment, we found that although auditory stimulation alone did not induce oscillations in visual performance, auditory stimulation did enhance the effects of concurrent visual stimulation. Notably, this enhancement did not require synchronous presentation of stimuli. These observations are consistent with recent reports that passive auditory stimulation beyond 5 Hz induces neither auditory perceptual oscillations nor visual cortical oscillations and suggest limits to the extent of cross-modal entrainment. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Building the multitasking brain: An integrated perspective on functional brain activation during task-switching and dual-tasking.

Multitasking behavior is associated with well-known performance costs, but the question of why individuals falter when attempting to manage multiple streams of information remains difficult to answer. One reason for this difficulty may be that multitasking costs are often characterized by isolating component processes that are studied largely independently. In this study, we instead integrate two commonly studied substrates of multitasking, task-switching and dual-tasking, within the same procedural context. This method allows not only a direct comparison of performance costs associated with different demand types but also examination of their interaction. We measured functional brain activation in thirty healthy young adults as they completed a block-design version of the task, observing consistent and separable patterns of frontoparietal activation as a function of demand type. Broadly, task-switching was associated with activation of left premotor and inferior parietal regions, and dual-tasking was associated with activation in regions of right prefrontal and inferior parietal cortex. In the interaction condition, we observed a distributed bilateral pattern of activation across the areas associated with each demand in isolation. These results provide both behavioral and neuroimaging evidence that task-switching and dual-tasking demands can be dissociated and contribute to multitasking costs in unique and separable ways.

Evaluation of a clinically practical, ERP-based neurometric battery: Application to age-related changes in brain function.

OBJECTIVE: Event-related potentials (ERPs) show promise as markers of neurocognitive dysfunction, but conventional recording procedures render measurement of many ERP-based neurometrics clinically impractical. The purpose of this work was (a) to develop a brief neurometric battery capable of eliciting a broad profile of ERPs in a single, clinically practical recording session, and (b) to evaluate the sensitivity of this neurometric profile to age-related changes in brain function. METHODS: Nested auditory stimuli were interleaved with visual stimuli to create a 20-min battery designed to elicit at least eight ERP components representing multiple sensory, perceptual, and cognitive processes (Frequency & Gap MMN, P50, P3, vMMN, C1, N2pc, and ERN). Data were recorded from 21 younger and 21 high-functioning older adults. RESULTS: Significant multivariate differences were observed between ERP profiles of younger and older adults. Metrics derived from ERP profiles could be used to classify individuals into age groups with a jackknifed classification accuracy of 78.6%. CONCLUSIONS: Results support the utility of this design for neurometric profiling in clinical settings. SIGNIFICANCE: This study demonstrates a method for measuring a broad profile of ERP-based neurometrics in a single, brief recording session. These markers may be used individually or in combination to characterize/classify patterns of sensory and/or perceptual brain function in clinical populations.