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1.  Cingulo-Opercular Function during Word Recognition in Noise for Older Adults with Hearing Loss 
Experimental aging research  2016;42(1):67-82.
Background
Adaptive control, reflected by elevated activity in cingulo-opercular brain regions, optimizes performance in challenging tasks by monitoring outcomes and adjusting behavior. For example, cingulo-opercular function benefits trial-level word recognition in noise for normal hearing adults. Because auditory system deficits may limit the communicative benefit from adaptive control, we examined the extent to which cingulo-opercular engagement supports word recognition in noise for older adults with hearing loss (HL).
Methods
Participants were selected to form groups with Less HL (N = 12; PTA = 19.2 ± 4.8 dB HL) and More HL (N = 12; mean pure tone thresholds, PTA = 38.4 ± 4.5 dB HL, 0.25 to 8 kHz, both ears). A word recognition task was performed with words presented in multi-talker babble at +3 or +10 dB signal-to-noise ratios (SNRs) during a sparse acquisition fMRI experiment. The participants were middle-aged and older (ages: 64.1 ± 8.4 years) English speakers with no history of neurological or psychiatric diagnoses.
Results
Elevated cingulo-opercular activity occurred with increased likelihood of correct word recognition on the next trial (t(23) = 3.28, p = 0.003) and this association did not differ between hearing loss groups. During trials with word recognition errors, the More HL group exhibited higher Blood oxygen level-dependent (BOLD) contrast in occipital and parietal regions compared to the Less HL group. Across listeners, more pronounced cingulo-opercular activity during recognition errors was associated with better overall word recognition performance.
Conclusion
The trial-level word recognition benefit from cingulo-opercular activity was equivalent for both hearing loss groups. When speech audibility and performance levels are similar for older adults with mild to moderate hearing loss, cingulo-opercular adaptive control contributes to word recognition in noise.
doi:10.1080/0361073X.2016.1108784
PMCID: PMC4899824  PMID: 26683042
hearing loss; word recognition; adaptive control; attention
2.  Task-related vigilance during speech recognition in noise for older adults with hearing loss 
Experimental aging research  2016;42(1):64-85.
Background/Study Context
Vigilance refers to the ability to sustain and adapt attentional focus in response to changing task demands. For older adults with hearing loss, vigilant listening may be particularly effortful and variable across individuals. This study examined the extent to which neural responses to sudden, unexpected changes in task structure (e.g., from rest to speech recognition epochs) were related to pupillometry measures of listening effort.
Methods
Individual differences in the task-evoked pupil response during word recognition were used to predict functional MRI estimates of neural responses to salient transitions between quiet rest, noisy rest, and word recognition in unintelligible, fluctuating background noise. Participants included 29 older adults (M = 70.2 years old) with hearing loss (pure tone average across all frequencies = 36.1 dB HL, SD = 6.7).
Results
Individuals with a greater average pupil response exhibited a more vigilant pattern of responding on a standardized continuous performance test (response time variability across varying inter-stimulus intervals r(27) = .38, p = .04). Across participants there was widespread neural engagement of attention and sensory-related cortices in response to transitions between blocks of rest and word recognition conditions. Individuals who exhibited larger task-evoked pupil dilation also showed even greater activity in the right primary auditory cortex in response to changes in task structure.
Conclusion
Pupillometric estimates of speech recognition effort predicted variation in activity within cortical regions that were responsive to salient changes in the environment for older adults with hearing loss. The current study suggests that maintaining vigilant attention may come at the cost of increased listening effort.
doi:10.1080/0361073X.2016.1108712
PMCID: PMC4702493  PMID: 26683041
3.  Speech-perception training for older adults with hearing loss impacts word recognition and effort 
Psychophysiology  2014;51(10):1046-1057.
The current pupillometry study examined the impact of speech-perception training on word recognition and cognitive effort in older adults with hearing loss. Trainees identified more words at the follow-up than at the baseline session. Training also resulted in an overall larger and faster peaking pupillary response, even when controlling for performance and reaction time. Perceptual and cognitive capacities affected the peak amplitude of the pupil response across participants but did not diminish the impact of training on the other pupil metrics. Thus, we demonstrated that pupillometry can be used to characterize training-related and individual differences in effort during a challenging listening task. Importantly, the results indicate that speech-perception training not only affects overall word recognition, but also a physiological metric of cognitive effort, which has the potential to be a biomarker of hearing loss intervention outcome.
doi:10.1111/psyp.12242
PMCID: PMC4234634  PMID: 24909603
4.  Cortical Activity Predicts Which Older Adults Recognize Speech in Noise and When 
The Journal of Neuroscience  2015;35(9):3929-3937.
Speech recognition in noise can be challenging for older adults and elicits elevated activity throughout a cingulo-opercular network that is hypothesized to monitor and modify behaviors to optimize performance. A word recognition in noise experiment was used to test the hypothesis that cingulo-opercular engagement provides performance benefit for older adults. Healthy older adults (N = 31; 50–81 years of age; mean pure tone thresholds <32 dB HL from 0.25 to 8 kHz, best ear; species: human) performed word recognition in multitalker babble at 2 signal-to-noise ratios (SNR = +3 or +10 dB) during a sparse sampling fMRI experiment. Elevated cingulo-opercular activity was associated with an increased likelihood of correct recognition on the following trial independently of SNR and performance on the preceding trial. The cingulo-opercular effect increased for participants with the best overall performance. These effects were lower for older adults compared with a younger, normal-hearing adult sample (N = 18). Visual cortex activity also predicted trial-level recognition for the older adults, which resulted from discrete decreases in activity before errors and occurred for the oldest adults with the poorest recognition. Participants demonstrating larger visual cortex effects also had reduced fractional anisotropy in an anterior portion of the left inferior frontal-occipital fasciculus, which projects between frontal and occipital regions where activity predicted word recognition. Together, the results indicate that older adults experience performance benefit from elevated cingulo-opercular activity, but not to the same extent as younger adults, and that declines in attentional control can limit word recognition.
doi:10.1523/JNEUROSCI.2908-14.2015
PMCID: PMC4348188  PMID: 25740521
aging; attention; audition; control; perception; speech
5.  The Cingulo-Opercular Network Provides Word-Recognition Benefit 
The Journal of Neuroscience  2013;33(48):18979-18986.
Recognizing speech in difficult listening conditions requires considerable focus of attention that is often demonstrated by elevated activity in putative attention systems, including the cingulo-opercular network. We tested the prediction that elevated cingulo-opercular activity provides word-recognition benefit on a subsequent trial. Eighteen healthy, normal-hearing adults (10 females; aged 20–38 years) performed word recognition (120 trials) in multi-talker babble at +3 and +10 dB signal-to-noise ratios during a sparse sampling functional magnetic resonance imaging (fMRI) experiment. Blood oxygen level-dependent (BOLD) contrast was elevated in the anterior cingulate cortex, anterior insula, and frontal operculum in response to poorer speech intelligibility and response errors. These brain regions exhibited significantly greater correlated activity during word recognition compared with rest, supporting the premise that word-recognition demands increased the coherence of cingulo-opercular network activity. Consistent with an adaptive control network explanation, general linear mixed model analyses demonstrated that increased magnitude and extent of cingulo-opercular network activity was significantly associated with correct word recognition on subsequent trials. These results indicate that elevated cingulo-opercular network activity is not simply a reflection of poor performance or error but also supports word recognition in difficult listening conditions.
doi:10.1523/JNEUROSCI.1417-13.2013
PMCID: PMC3841458  PMID: 24285902
6.  Pupil size varies with word listening and response selection difficulty in older adults with hearing loss 
Psychophysiology  2012;50(1):23-34.
Listening to speech in noise can be exhausting, especially for older adults with impaired hearing. Pupil dilation is thought to track the difficulty associated with listening to speech at various intelligibility levels for young and middle-aged adults. This study examined changes in the pupil response with acoustic and lexical manipulations of difficulty in older adults with hearing loss. Participants identified words at two signal-to-noise ratios (SNRs) among options that could include a similar-sounding lexical competitor. Growth Curve Analyses revealed that the pupil response was affected by an SNR-by-lexical competition interaction, such that it was larger and more delayed and sustained in the harder SNR condition, particularly in the presence of lexical competition. Pupillometry detected these effects for correct trials and across reaction times, suggesting it provides additional evidence of task difficulty than behavioral measures alone.
doi:10.1111/j.1469-8986.2012.01477.x
PMCID: PMC3527636  PMID: 23157603
7.  Word Intelligibility and Age Predict Visual Cortex Activity during Word Listening 
Cerebral Cortex (New York, NY)  2012;22(6):1360-1371.
The distractibility that older adults experience when listening to speech in challenging conditions has been attributed in part to reduced inhibition of irrelevant information within and across sensory systems. Whereas neuroimaging studies have shown that younger adults readily suppress visual cortex activation when listening to auditory stimuli, it is unclear the extent to which declining inhibition in older adults results in reduced suppression or compensatory engagement of other sensory cortices. The current functional magnetic resonance imaging study examined the effects of age and stimulus intelligibility in a word listening task. Across all participants, auditory cortex was engaged when listening to words. However, increasing age and declining word intelligibility had independent and spatially similar effects: both were associated with increasing engagement of visual cortex. Visual cortex activation was not explained by age-related differences in vascular reactivity but rather auditory and visual cortices were functionally connected across word listening conditions. The nature of this correlation changed with age: younger adults deactivated visual cortex when activating auditory cortex, middle-aged adults showed no relation, and older adults synchronously activated both cortices. These results suggest that age and stimulus integrity are additive modulators of crossmodal suppression and activation.
doi:10.1093/cercor/bhr211
PMCID: PMC3357178  PMID: 21862447
aging; crossmodal; fMRI; speech perception; vascular reactivity
8.  Inferior frontal sensitivity to common speech sounds is amplified by increasing word intelligibility 
Neuropsychologia  2011;49(13):3563-3572.
The left inferior frontal gyrus (LIFG) exhibits increased responsiveness when people listen to words composed of speech sounds that frequently co-occur in the English language (Vaden, Piquado, Hickok, 2011), termed high phonotactic frequency (Vitevitch & Luce, 1998). The current experiment aimed to further characterize the relation of phonotactic frequency to LIFG activity by manipulating word intelligibility in participants of varying age. Thirty six native English speakers, 19–79 years old (mean = 50.5, sd = 21.0) indicated with a button press whether they recognized 120 binaurally presented consonant-vowel-consonant words during a sparse sampling fMRI experiment (TR = 8 sec). Word intelligibility was manipulated by low-pass filtering (cutoff frequencies of 400 Hz, 1000 Hz, 1600 Hz, and 3150 Hz). Group analyses revealed a significant positive correlation between phonotactic frequency and LIFG activity, which was unaffected by age and hearing thresholds. A region of interest analysis revealed that the relation between phonotactic frequency and LIFG activity was significantly strengthened for the most intelligible words (low-pass cutoff at 3150 Hz). These results suggest that the responsiveness of the left inferior frontal cortex to phonotactic frequency reflects the downstream impact of word recognition rather than support of word recognition, at least when there are no speech production demands.
doi:10.1016/j.neuropsychologia.2011.09.008
PMCID: PMC3207245  PMID: 21925521
9.  Age-related differences in gap detection: Effects of task difficulty and cognitive ability 
Hearing research  2009;264(1-2):21-29.
Differences in gap detection for younger and older adults have been shown to vary with the complexity of the task or stimuli, but the factors that contribute to these differences remain unknown. To address this question, we examined the extent to which age-related differences in processing speed and workload predicted age-related differences in gap detection. Gap detection thresholds were measured for 10 younger and 11 older adults in two conditions that varied in task complexity but used identical stimuli: (1) gap location fixed at the beginning, middle, or end of a noise burst and (2) gap location varied randomly from trial to trial from the beginning, middle, or end of the noise. We hypothesized that gap location uncertainty would place increased demands on cognitive and attentional resources and result in significantly higher gap detection thresholds for older but not younger adults. Overall, gap detection thresholds were lower for the middle location as compared to beginning and end locations and were lower for the fixed than the random condition. In general, larger age-related differences in gap detection were observed for more challenging conditions. That is, gap detection thresholds for older adults were significantly larger for the random condition than for the fixed condition when the gap was at the beginning and end locations but not the middle. In contrast, gap detection thresholds for younger adults were not significantly different for the random and fixed condition at any location. Subjective ratings of workload indicated that older adults found the gap-detection task more mentally demanding than younger adults. Consistent with these findings, results of the Purdue Pegboard and Connections tests revealed age-related slowing of processing speed. Moreover, age group differences in workload and processing speed predicted gap detection in younger and older adults when gap location varied from trial to trial; these associations were not observed when gap location remained constant across trials. Taken together, these results suggest that age-related differences in complex measures of auditory temporal processing may be explained, in part, by age-related deficits in processing speed and attention.
doi:10.1016/j.heares.2009.09.017
PMCID: PMC2868108  PMID: 19800958
aging; auditory temporal processing; gap detection; processing speed; workload; cognitive
10.  Speech recognition in younger and older adults: a dependency on low-level auditory cortex 
A common complaint of older adults is difficulty understanding speech, especially in challenging listening environments. In addition to well known declines in the peripheral auditory system that reduce audibility, age-related changes in central auditory and attention-related systems are hypothesized to have additive negative effects on speech recognition. We examined the extent to which functional and structural differences in speech- and attention-related cortex predicted differences in word recognition between 18 younger adults (19–39 years) and 18 older adults (61–79 years). Subjects performed a word recognition task in an MRI scanner where the intelligibility of words was parametrically varied. Older adults exhibited significantly poorer word recognition in a challenging listening condition compared to younger adults. An anteromedial Heschl’s gyrus/superior temporal gyrus (HG/STG) region, engaged by the word recognition task, exhibited age group differences in gray matter volume and predicted word recognition in younger and older adults. Age group differences in anterior cingulate (ACC) activation were also observed. The association between HG gray matter volume, word recognition, and ACC activation was present after controlling for hearing loss. In younger and older adults, causal path modeling analyses demonstrated that individual variation in left HG/STG morphology affected word recognition performance, which was reflected by error monitoring activity in the dorsal ACC. These results have clinical implications for rehabilitation and suggest that some of the perceptual difficulties experienced by older adults are due to structural changes in HG/STG. More broadly, the results suggest the possibility that aging may exaggerate developmental limitations on the ability to recognize speech.
doi:10.1523/JNEUROSCI.0412-09.2009
PMCID: PMC2717741  PMID: 19439585
aging; auditory cortex; gray matter; word recognition; auditory; speech

Results 1-10 (10)