Suess, N. | bioRxiv Science

bioRxiv2019

Phantom auditory perception (tinnitus) is characterised by stronger anticipatory auditory predictions

How phantom perceptions arise and the factors that make individuals prone to such experiences are not well understood. An attractive phenomenon to study these questions is tinnitus, a very common auditory phantom perception which is not explained by hyperactivity in the auditory pathway alone. Our framework posits that a predisposition to developing (chronic) tinnitus is dependent on individual traits relating to the formation and utilization of sensory predictions. Predictions of auditory stimulus frequency (remote from tinnitus frequency) were studied using a paradigm parametrically modulating regularity (i.e. predictability) of tone sequences and applying decoding techniques on magnetoencephalographic (MEG) data. For processes likely linked to short-term memory, individuals with tinnitus showed an enhanced anticipatory prediction pattern associated with increasing sequence regularity. In contrast, individuals without tinnitus engaged the same processes following the onset of the to-be-decoded sound. We posit that this tendency to optimally anticipate static and changing auditory inputs may determine which individuals faced with persistent auditory pathway hyperactivity factor it into auditory predictions, and thus perceive it as tinnitus. While our study constitutes a first step relating vulnerability to tinnitus with predictive processing, longitudinal studies are needed to confirm the predisposition model of tinnitus development.

neuroscience↗

bioRxiv2019

Supramodal selective attention differentially adjusts frequency and phase of entrained oscillations in primary sensory areas and the dorsal attention network

Continuously prioritizing behaviourally relevant information from the environment for improved stimulus processing is a crucial function of attention. Low-frequency phase alignment of neural activity in primary sensory areas, with respect to attended/ignored features has been suggested to support top-down prioritization. Phase adjustment in frontoparietal regions has not been widely studied, despite general implication of these in top-down selection of information. In the current MEG study, we investigated how ongoing oscillatory activity of both sensory and non-sensory brain regions are differentially impacted by attentional focus. Participants performed an established intermodal selective attention task, where low-frequency auditory (1.6 Hz) and visual (1.8 Hz) stimuli were presented simultaneously. We instructed participants to either attend to the auditory or to the visual stimuli and to detect targets while ignoring the other stimulus stream. As expected, the strongest phase adjustment was observed in primary sensory regions for auditory and for visual stimulation, independent of attentional focus. We found greater differences in phase locking between attended and ignored stimulation for the visual modality. Interestingly, auditory temporal regions show small but significant attention-dependent entrainment even for visual stimulation. Extending findings from invasive recordings in non-human primates, we demonstrate an effect of attentional focus on the phase of the entrained oscillations in auditory and visual cortex which may be driven by phase locked increases of induced power. In contrast to the effects in sensory areas, attentional focus adjusted the peak frequencies in nonsensory areas. Spatially these areas show a striking overlap with core regions of the dorsal attention network and the frontoparietal network. This suggests that these areas prioritize the attended modality by optimally exploiting the temporal structure of stimulation. Overall, our study complements and extends previous work by showing a differential effect of attentional focus on entrained oscillations in primary sensory areas and frontoparietal areas.

neuroscience↗