Adverse Listening Conditions and Memory Load Drive a Common Alpha Oscillatory Network

Abstract

How does acoustic degradation affect the neural mechanisms of working memory? Enhanced alpha oscillations (8 -13 Hz) during retention of items in working memory are often interpreted to reflect increased demands on storage and inhibition. We hypothesized that auditory signal degradation poses an additional challenge to human listeners partly because it draws on the same neural mechanisms. In an adapted Sternberg paradigm, auditory memory load and acoustic degradation were parametrically varied and the magnetoencephalographic response was analyzed in the time-frequency domain. Notably, during the stimulus-free delay interval, alpha power monotonically increased at central-parietal sensors as functions of memory load (higher alpha power with more memory load) and of acoustic degradation (also higher alpha power with more severe acoustic degradation). This alpha effect was superadditive when highest load was combined with most severe degradation. Moreover, alpha oscillatory dynamics during stimulus-free delay were predictive of response times to the probe item. Source localization of alpha power during stimulus-free delay indicated that alpha generators in right parietal, cingulate, supramarginal, and superior temporal cortex were sensitive to combined memory load and acoustic degradation. In summary, both challenges of memory load and acoustic degradation increase activity in a common alpha-frequency network. The results set the stage for future studies on how chronic or acute degradations of sensory input affect mechanisms of executive control.

Hearing Impairment and Cognitive Energy: The Framework for Understanding Effortful Listening (FUEL)

“…Recent research has shown that acoustic degradation (vocoding) of the signal increases alpha oscillations during listening, suggesting that enhanced alpha power is not only modulated by changing domain-general requirements such as the number of stored items, but that challenges arising from mild-to-severe sensory degradation also affect this system. Both manipulations cause an enhancement of oscillatory power in the same time-frequency range (Obleser et al 2012). Notably, a recent study on alpha power modulation using a working memory paradigm in older hearing-impaired listeners showed that the degree of hearing loss predicted alpha power enhancement (Petersen et al 2015).…”

Context-dependent impact of presuppositions on early magnetic brain responses during speech perception

“…Error bars indicate the SE for intrasubject comparisons. (Spitzer, Fleck, & Blankenburg, 2014;Obleser, Wöstmann, Hellbernd, Wilsch, & Maess, 2012b), difficulty of lexical integration (Strauss, Kotz, Scharinger, & Obleser, 2014), and processing effort in case of degraded speech (Obleser et al, 2012b;Obleser & Weisz, 2012). Since some studies found alpha activity to correlate with task difficulty while others reported the opposite constellation, alpha power and task demands seem to be related in a rather complex manner.…”

The Moderating Effect of Success Importance on the Relationship Between Listening Demand and Listening Effort

“…XXXX; Kuchinsky et al 2013;Piquado et al 2010;Zekveld & Kramer 2014;Zekveld et al 2010), heart rate, skin conductance, skin temperature, EMG activity (e.g., Mackersie & Cones 2011), heart rate variability (e.g., Mackersie & Calderon-Moultrie, this issue, pp. XXXX), fMRI activity (Wild et al 2012), ERPs (Obleser & Kotz 2011), and EEG alpha power (Obleser et al 2012) (see McGarrigle et al 2014, for a summary of listening effort studies using physiological measures published between 2008 and 2013). A common element of these psychophysiological studies on listening effort is that they examined the effects of variables related to listening difficulty on the physiological measures of interest.…”