Biology subjects

Prinsloo, K. D.

Publications and source records attributed to Prinsloo, K. D..

2 recordsLinked to original sources

bioRxiv2022

Enhanced anticipatory biasing of visuospatial attention in deaf native-signing adults indexed by alpha-band (8-14 Hz) oscillatory neural activity

Deaf people show increased visuospatial attention abilities, especially towards peripheral inputs, but the neural mechanisms of these heightened abilities are not yet understood. In hearing individuals, topographically-specific alpha-band oscillatory activity (8-14 Hz) over parieto-occipital regions has been associated with active suppression of irrelevant locations. Here, we asked whether increases in this spatially-specific anticipatory oscillatory mechanism might underpin enhanced visuospatial attention abilities in deaf individuals, on the premise that deaf people might be more adept at transiently engaging and disengaging attentional processes involved in processing peripheral inputs. An alternative hypothesis was that deaf individuals might not produce lateralized alpha-band activity, because of the need to continuously monitor the periphery due to the absence of an auxiliary auditory spatial alerting system. High-density electroencephalography was recorded from 20 deaf native signers and 20 hearing non-signers performing a cued covert visuospatial attention task. Deaf participants responded significantly more rapidly and accurately and showed highly typical alpha-band lateralization during the cue-target interval of the task. Topographic analysis showed a greater extent of alpha-band anticipatory activity over right parietal scalp, suggesting sequestration of extra-visual attentional circuits (i.e., unused auditory regions), and post-hoc analysis pointed to substantially earlier onset of this activity during the cue-target interval. The presence of cue-evoked anticipatory alpha lateralization in deaf participants suggests that they are rapidly engaging and disengaging attentional processes involved in orienting attention to the periphery. The earlier and more extensive engagement of these anticipatory oscillatory processes may contribute to the improved visuospatial performance observed in these individuals. Significance StatementPrior to this study, it was not known whether deaf people demonstrate lateralization of alpha-band oscillatory electroencephalographic (EEG) activity over the posterior region of the brain, which plays a role in the suppression of uncued regions of space during cued visuospatial attention tasks. We found that this lateralized pattern was observable in deaf participants and was not significantly different from that seen in hearing participants, except that alpha activity onsets earlier in deaf participants. However, when cue directions were collapsed, the scalp topographies of deaf participants showed a greater distribution of alpha activity, suggesting that they recruited a brain region typically reserved for audiospatial attentional control during the visuospatial attention task. Additionally, deaf participants responded significantly more quickly and accurately compared to hearing participants, demonstrating increased visuospatial attention abilities.

neuroscience↗

bioRxiv2020

General auditory and speech-specific contributions to cortical envelope tracking revealed using auditory chimeras

1.In recent years research on natural speech processing has benefited from recognizing that low frequency cortical activity tracks the amplitude envelope of natural speech. However, it remains unclear to what extent this tracking reflects speech-specific processing beyond the analysis of the stimulus acoustics. In the present study, we aimed to disentangle contributions to cortical envelope tracking that reflect general acoustic processing from those that are functionally related to processing speech. To do so, we recorded EEG from subjects as they listened to "auditory chimeras" - stimuli comprised of the temporal fine structure (TFS) of one speech stimulus modulated by the amplitude envelope (ENV) of another speech stimulus. By varying the number of frequency bands used in making the chimeras, we obtained some control over which speech stimulus was recognized by the listener. No matter which stimulus was recognized, envelope tracking was always strongest for the ENV stimulus, indicating a dominant contribution from acoustic processing. However, there was also a positive relationship between intelligibility and the tracking of the perceived speech, indicating a contribution from speech specific processing. These findings were supported by a follow-up analysis that assessed envelope tracking as a function of the (estimated) output of the cochlea rather than the original stimuli used in creating the chimeras. Finally, we sought to isolate the speech-specific contribution to envelope tracking using forward encoding models and found that indices of phonetic feature processing tracked reliably with intelligibility. Together these results show that cortical speech tracking is dominated by acoustic processing, but also reflects speech-specific processing. This work was supported by a Career Development Award from Science Foundation Ireland (CDA/15/3316) and a grant from the National Institute on Deafness and Other Communication Disorders (DC016297). The authors thank Dr. Aaron Nidiffer, Dr. Aisling OSullivan, Thomas Stoll and Lauren Szymula for assistance with data collection, and Dr. Nathaniel Zuk, Dr. Aaron Nidiffer, Dr. Aisling OSullivan for helpful comments on this manuscript. 2. Significance StatementActivity in auditory cortex is known to dynamically track the energy fluctuations, or amplitude envelope, of speech. Measures of this tracking are now widely used in research on hearing and language and have had a substantial influence on theories of how auditory cortex parses and processes speech. But, how much of this speech tracking is actually driven by speech-specific processing rather than general acoustic processing is unclear, limiting its interpretability and its usefulness. Here, by merging two speech stimuli together to form so-called auditory chimeras, we show that EEG tracking of the speech envelope is dominated by acoustic processing, but also reflects linguistic analysis. This has important implications for theories of cortical speech tracking and for using measures of that tracking in applied research.

neuroscience↗