Busy and confused? High risk of missed alerts in the cockpit: an electrophysiological study

Of evolutionary importance, the ability to react to unexpected auditory stimuli remains critical today, especially in settings such as aircraft cockpits or air traffic control towers, characterized by high mental and auditory loads. Evidences show that both factors can negatively impact auditory attention and prevent appropriate reactions in hazardous situations. In the present study, sixty participants performed a simulated aviation task, varying in terms of mental load (no, low, high mental load), that was embedded with a concurrent tone detection paradigm, in which auditory load was manipulated by the number of different tones (1, 2 or 3). We measured both detection performance (miss, false alarm) and brain activity (event-related potentials) related to the target tone. Our results showed that both mental and auditory loads affected tone detection performance. Importantly, their combined effects had a massive impact on the percentage of missed target tones. While, in the no mental load condition, miss rate was very low with 1 (0.53%) and 2 tones (1.11%), it increased drastically with 3 tones (24.44%), and this effect was accentuated as mental load increased, yielding to the higher miss rate in the 3-tone paradigm under high mental load conditions (68.64%). Increased mental load, auditory load, and miss rate, were all associated with disrupted brain response to the target tone as showed by reductions of the P3b amplitude. In sum, our results highlight the importance of balancing mental and auditory loads to maintain or improve efficient reactions to alarms in complex environment.

Target detection in healthy 4-week old piglets from a passive two-tone auditory oddball paradigm

Background Passive auditory oddball tests are effort independent assessments that evaluate auditory processing and are suitable for paediatric patient groups. Our goal was to develop a two-tone auditory oddball test protocol and use this clinical assessment in an immature large animal model. Event-related potentials captured middle latency P1, N1, and P2 responses in 4-week old (N = 16, female) piglets using a custom piglet 32- electrode array on 3 non-consecutive days. The effect of target tone frequency (250 Hz and 4000 Hz) on middle latency responses were tested in a subset of animals. Results Results show that infrequent target tone pulses elicit greater N1 amplitudes than frequent standard tone pulses. There was no effect of day. Electrodes covering the front of the head tend to elicit greater waveform responses. P2 amplitudes increased for higher frequency target tones (4000 Hz) than the regular 1000 Hz target tones (p < 0.05). Conclusions Two-tone auditory oddball tests produced consistent responses day-to-day. This clinical assessment was successful in the immature large animal model.

Auditory Target Detection Enhances Visual Processing and Hippocampal Functional Connectivity

Though dividing one’s attention between two input streams typically impairs performance, detecting a behaviorally relevant stimulus can sometimes enhance the encoding of task-irrelevant information presented at the same time. Previous research has shown that temporal selection of this kind boosts visual cortical activity and incidental memory. An important and yet unanswered question is whether such effects are reflected in processing quality and functional connectivity in visual regions and the hippocampus. In this fMRI study, participants were asked to memorize a stream of images and press a button when they heard an auditory tone of a prespecified pitch. Images could be presented with a target tone, with a distractor tone, or without a tone. Auditory target detection increased activity throughout the ventral visual cortex but lowered it in the hippocampus. These effects were accompanied by a widespread enhancement in functional connectivity between the ventral visual cortex and the hippocampus. Image category classification accuracy was higher on target tone trials than on distractor and no tone trials in the fusiform gyrus and the parahippocampal gyrus. This effect was stronger in clusters whose activity was more correlated with the hippocampus on target tone than on distractor tone trials. In agreement with accounts suggesting that subcortical noradrenergic influences play a role in temporal selection, auditory target detection also caused an increase in locus coeruleus activity and phasic pupil responses. These findings outline a network of cortical and subcortical regions that are involved in the selection and processing of information presented at behaviorally relevant moments.Significance StatementAttention influences the degree to which we remember everyday experiences. This study examines the neural mechanisms involved in committing important events to memory. It links the selection of important information in time (temporal selection) to enhanced functional connectivity between brain regions involved in perception and encoding. It also suggests the involvement of a small brainstem structure, the locus coeruleus (LC), whose degeneration is increasingly associated with cognitive decline in aging. The process of encoding behaviorally relevant events into episodic memory thus involves large-scale, coordinated activation spanning cortical and subcortical regions.

Stop Laryngeal Distinctions Driven by Contrastive Effects of Neighboring Tones

This study examined contrastive effects of neighboring tones that give rise to a systematic asymmetry in stop perception. Korean-speaking learners of Mandarin Chinese and naïve listeners labeled voiceless unaspirated stops preceded or followed by low or high extrinsic tonal context (e.g., maLO.pa vs. maHI.pa) either as lenis (associated with a low F0 at the vowel onset) or as fortis stops (with a high F0). Further, the target tone itself varied between level and rising (e.g., maLO.paLEV vs. maLO.paRIS). Both groups of listeners showed significant contrastive effects of extrinsic context. Specifically, more lenis responses were elicited in a high tone context than in a low one, and vice versa. This indicates that the onset F0 of a stop is perceived lower in a high tone context, which, in turn, provides positive evidence for lenis stops. This effect was more clearly pronounced for the level than for the contour tone target and also for the preceding than for the following context irrespective of linguistic experience. Despite qualitative similarities, learners showed larger effects for all F0 variables, indicating that the degree of context effects may be enhanced by one’s phonetic knowledge, namely sensitivity to F0 cues along with the processing of consecutive tones acquired through learning a tone language.

Comparative Analysis between Robert Burns’ “Auld Lang Syne” and Alfred Tennyson’s “Break, Break, Break”

Robert Burns’ “Auld Lang Syne” and Alfred Tennyson’s “Break, Break, Break” are two well-known poems on friendship. A detailed comparison between the two poems from the perspective of target, tone and writing techniques is made for the purpose of better understanding and appreciating them.

Implicit temporal predictability biases slow oscillatory phase in auditory cortex and enhances pitch discrimination sensitivity

Can human listeners use strictly implicit temporal contingencies in auditory input to form temporal predictions, and if so, how are these predictions represented endogenously? To assess this question, we implicitly manipulated foreperiods in an auditory pitch discrimination task. Unbeknownst to participants, the pitch of the standard tone could either be deterministically predictive of the onset of the target tone, or convey no predictive information. Both conditions were presented interleaved in one stream, and separated by variable inter-stimulus intervals such that there was no dominant stimulus rhythm throughout. Even though participants were unaware of the implicit temporal contingencies, pitch discrimination sensitivity (i.e. the slope of the psychometric function) increased when the onset of the target tone was predictable in time (N = 49). Concurrently recorded EEG data (N = 24) revealed that standard tones which initiated temporal predictions evoked a more negative N1 component than non-predictive standards, and were followed by an increase in delta power during the foreperiod. Furthermore, the phase angle of delta oscillations (1–3Hz) evoked by the standard tone predicted pitch discrimination sensitivity at the target tone (1.75 s later on average), which suggests that temporal predictions can be initiated by an optimized delta phase reset. In sum, we show that auditory perception benefits from implicit temporal contingencies, and provide evidence for a role of slow neural oscillations in the endogenous representation of temporal predictions, in absence of exogenously driven entrainment to rhythmic input.Significance StatementTemporal contingencies are ubiquitous in sensory environments, especially in the auditory domain, and have been shown to facilitate perception and action. Yet, how these contingencies in exogenous inputs are transformed into an endogenous representation of temporal predictions is not known. Here, we implicitly induced temporal predictability in the absence of a rhythmic input structure, that is without exogenously driven entrainment of neural oscillations. Our results show that even implicit and non-rhythmic temporal predictions are extracted and used by human observers, underlining the role of timing in sensory processing. Furthermore, our EEG results point towards an instrumental role of delta oscillations in initiating temporal predictions by an optimized phase reset in response to a temporally predictive cue.

A new paradigm for temporal masking assessment: pilot study

PURPOSE: To determine the feasibility and applicability of a clinical backward masking test, focusing on the analysis of inter-stimuli interval, and not on the intensity thresholds as it has been traditionally done, thus proposing a new paradigm for temporal masking assessment.METHOD: The test consisted of the presentation of a target tone of 1.000 Hz followed by a broadband masking noise (950-1.050 Hz), with inter-stimuli interval of 0, 10, 20, 50 and 100 ms. The stimuli were presented monaurally to both ears, with intensity ratio between masker and target tone varying between -10, -20, -30 and -40 dB. Twenty undergraduate students, without hearing or auditory processing complaints, participated in this study.RESULTS: Regardless of the signal-to-noise ratio, we observed decrease of average performance according to the decrease of the interval between stimuli. We also observed the indication that little or no masking occurs at the 100 ms interval, suggesting this interval is unsuitable for temporal masking assessment. The average interval threshold was below 27 ms for all investigated intensities, and increased 9 ms with every increase of 10 dB at signal-to-noise ratio. The signal-to-noise ratios of -20 and -30 were the best ratios for the test application.CONCLUSION: The paradigm proposed in this pilot study proved to be feasible, easy to apply, and trustworthy, being compatible with other researches which are the foundation for the study of temporal masking. This theme deserves further studies, continuing the analysis initiated here.

Selection of events in time enhances activity throughout early visual cortex

Temporal selection poses unique challenges to the perceptual system. Selection is needed to protect goal-relevant stimuli from interference from new sensory input. In addition, contextual information that occurs at the same time as goal-relevant stimuli may be critical for learning. Using fMRI, we characterized how visual cortical regions respond to the temporal selection of auditory and visual stimuli. Critically, we focused on brain regions that are not involved in processing the target itself. Participants pressed a button when they heard a prespecified target tone and did not respond to other tones. Although more attention was directed to auditory input when the target tone was selected, activity in primary visual cortex increased more after target tones than after distractor tones. In contrast to spatial attention, this effect was larger in V1 than in V2 and V3. It was present in regions not typically involved in representing the target stimulus. Additional experiments demonstrated that these effects were not due to multimodal processing, rare targets, or motor responses to the targets. Thus temporal selection of behaviorally relevant stimuli enhances, rather than reduces, activity in perceptual regions involved in processing other information.