Alpha and theta oscillations on a visual strategic processing task in age-related hearing loss

Abstract

Introduction: Emerging evidence suggests changes in several cognitive control processes in individuals with age-related hearing loss (ARHL). However, value-directed strategic processing, which involves selectively processing salient information based on high value, has been relatively unexplored in ARHL. Our previous work has shown behavioral changes in strategic processing in individuals with ARHL. The current study examined event-related alpha and theta oscillations linked to a visual, value-directed strategic processing task in 19 individuals with mild untreated ARHL and 17 normal hearing controls of comparable age and education.

Methods: Five unique word lists were presented where words were assigned high- or low-value based on the letter case, and electroencephalography (EEG) data was recorded during task performance.

Results: The main effect of the group was observed in early time periods. Specifically, greater theta synchronization was seen in the ARHL group relative to the control group. Interaction between group and value was observed at later time points, with greater theta synchronization for high- versus low-value information in those with ARHL.

Discussion: Our findings provide evidence for oscillatory changes tied to a visual task of value-directed strategic processing in individuals with mild untreated ARHL. This points towards modality-independent neurophysiological changes in cognitive control in individuals with mild degrees of ARHL and adds to the rapidly growing literature on the cognitive consequences of ARHL.

Keywords: age-related hearing loss; alpha; cognitive control; event-related electroencephalography; neural oscillations; older adults; strategic processing; theta.

Figure 1

Audiograms for ARHL and NH groups. Average of air conduction hearing thresholds for both ears across frequencies in ARHL and NH groups. Error bars represent standard errors. ARHL, age-related hearing loss; NH, normal hearing.

Figure 2

Strategic processing task schematic. Lowercase or uppercase words served as high- or low-value words depending on task version. When the word “REMEMBER” was presented, participants verbally recalled words from that list. Responses were recorded on paper and scored for each of the five lists.

Figure 3

Electrode clusters used for Event-Related Spectral Perturbations (ERSP) power estimation. Solid boxes represent electrode clusters for theta analyses and dotted boxes represent clusters for alpha analyses.

Figure 4

Boxplots depicting behavioral data. The figure on the left depicts boxplots for number of words recalled and figure on the right depicts boxplots for total points earned. Horizontal lines represent median power, with boxes representing the interquartile range and whiskers extending to minimum and maximum values. ARHL, age-related hearing loss, NH, normal hearing. ^*p ≤ 0.05.

Figure 5

ERSP comparisons for theta band at prefrontal electrode cluster for interaction effects between group and value. Spectrograms illustrate differences between groups (ARHL/NH) and value (high-low-value) for theta band (4 to 8 Hz) at the prefrontal electrode cluster. The 0 ms time point (solid vertical line) represents stimulus onset. Dashed black rectangles indicate the time windows in which significant interaction effects between group and value were observed (also see Table 5). ARHL, age- related hearing loss; NH, normal hearing.

Figure 6

ERSP comparisons for alpha band at centroparietal electrode cluster for interaction effects between group and value. Spectrograms illustrate differences between groups (ARHL/NH) and value (high−/low-value) for alpha band (8–12 Hz) at the centroparietal electrode cluster. The 0 ms time point (solid vertical line) represents stimulus onset. Dashed black rectangles indicate the time windows in which significant interaction effects between group and value were observed (also see Table 5). ARHL, age-related hearing loss; NH, normal hearing.

Figure 7

Schematic of main findings. Top part of the figure represents theta findings; bottom part shows alpha findings. Orange dotted box shows findings of main effect of group; red solid boxes show findings of main effect of value; blue dashed boxes show findings of interaction effect between group and value.