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We show that sleep deprivation in otherwise normal and healthy adults can be detected through machine-learning analysis of vocal recordings. Importantly, we used fully generic acoustic features, derived from auditory models, together with our own machine learning interpretation method, derived from neuroscience. Sleep deprivation impacted two broad types of acoustic features: one related to speech rhythms, the other related to the timbre of the voice. Such features plausibly reflect two independent physiological processes: one explicit, the cognitive control of speech production, and the other implicit, the inflammation of the vocal apparatus. Crucially, the relative balance of the two processes varied widely across individuals, consistent with the known but unexplained variability in responses to sleep deprivation. Overall, our results suggest that the voice may be used as a “sleep stethoscope” to characterize the individual effects of sleep deprivation. Moreover, the method we applied is fully general and could be adapted to any future investigation of vocal biomarkers using machine-learning techniques.Author summarySleep deprivation has an ever-increasing impact on individuals and societies, from accidents to chronic conditions costing billions to health systems. Yet, to date, there is no quick and objective test for sleep deprivation. We show that sleep deprivation can be detected at the individual level with voice recordings, outlining future cost-effective and non-invasive “sleep stethoscopes”. Importantly, we focused on interpretability, which identified two independent physiological effects of sleep deprivation: a change in prosody, related to cognitive control, and a change in timbre, related to inflammation. This also revealed a striking variability in individual reactions to the same deprivation. The neuroscientific framework we developed, combining auditory models and machine learning, is freely available and could be adapted to any vocal biomarker.

International audience; Key points: In quiet, envelope tracking in the low amplitude modulation range (

International audience; Frequency modulation (FM) is assumed to be detected through amplitude modulation (AM) created by cochlear filtering for modulation rates above 10 Hz and carrier frequencies (f c) above 4 kHz. If this is the case, a model of modulation perception based on the concept of AM filters should predict masking effects between AM and FM. To test this, masking effects of sinusoidal AM on sinusoidal FM detection thresholds were assessed on normal-hearing listeners as a function of FM rate, f c , duration, AM rate, AM depth, and phase difference between FM and AM. The data were compared to predictions of a computational model implementing an AM filter-bank. Consistent with model predictions, AM masked FM with some AM-masking-AM features (broad tuning and effect of AM-masker depth). Similar masking was predicted and observed at f c ¼ 0.5 and 5 kHz for a 2 Hz AM masker, inconsistent with the notion that additional (e.g., temporal fine-structure) cues drive slow-rate FM detection at low f c. However, masking was lower than predicted and, unlike model predictions, did not show beating or phase effects. Broadly, the modulation filter-bank concept successfully explained some AM-masking-FM effects, but could not give a complete account of both AM and FM detection.

International audience; Languages tend to license segmental contrasts where they are maximally perceptible, i.e. where more perceptual cues to the contrast are available. For strident fricatives, the most salient cues to the presence of voicing are low-frequency energy concentrations and fricative duration, as voiced fricatives are systematically shorter than voiceless ones. Cross-linguistically, the voicing contrast is more frequently realized word-initially than word-finally, as for obstruents. We investigate the phonetic underpinnings of this asymmetric behavior at the word edges, focusing on the availability of durational cues to the contrast in the two positions. To assess segmental duration, listeners rely on temporal markers, i.e. jumps in acoustic energy which demarcate segmental boundaries, thereby facilitating duration discrimination. We conducted an acoustic analysis of wordinitial and word-final strident fricatives in American English. We found that temporal markers are sharper at the left edge of word-initial fricatives than at the right edge of word-final fricatives, in terms of absolute value of the intensity slope, in the high-frequency region. These findings allow us to make predictions about the availability of durational cues to the voicing contrast in the two positions.

Learning about new sounds is essential for cochlear-implant and normal-hearing listeners alike, with the additional challenge for implant listeners that spectral resolution is severely degraded. Here, a task measuring the rapid learning of slow or fast stochastic temporal sequences [Kang, Agus, and Pressnitzer (2017). J. Acoust. Soc. Am. 142, 2219-2232] was performed by cochlear-implant (N = 10) and normal-hearing (N = 9) listeners, using electric or acoustic pulse sequences, respectively. Rapid perceptual learning was observed for both groups, with highly similar characteristics. Moreover, for cochlear-implant listeners, an additional condition tested ultra-fast electric pulse sequences that would be impossible to represent temporally when presented acoustically. This condition also demonstrated learning. Overall, the results suggest that cochlear-implant listeners have access to the neural plasticity mechanisms needed for the rapid perceptual learning of complex temporal sequences.

Sensing the movement of fast objects within our visual environments is essential for controlling actions. It requires online estimation of motion direction and speed. We probed human speed representation using ocular tracking of stimuli of different statistics. First, we compared ocular responses to single drifting gratings (DGs) with a given set of spatiotemporal frequencies to broadband motion clouds (MCs) of matched mean frequencies. Motion energy distributions of gratings and clouds are point-like, and ellipses oriented along the constant speed axis, respectively. Sampling frequency space, MCs elicited stronger, less variable, and speed-tuned responses. DGs yielded weaker and more frequency-tuned responses. Second, we measured responses to patterns made of two or three components covering a range of orientations within Fourier space. Early tracking initiation of the patterns was best predicted by a linear combination of components before nonlinear interactions emerged to shape later dynamics. Inputs are supralinearly integrated along an iso-velocity line and sublinearly integrated away from it. A dynamical probabilistic model characterizes these interactions as an excitatory pooling along the iso-velocity line and inhibition along the orthogonal “scale” axis. Such crossed patterns of interaction would appropriately integrate or segment moving objects. This study supports the novel idea that speed estimation is better framed as a dynamic channel interaction organized along speed and scale axes.

It is still unclear whether the gradual improvement in amplitude-modulation (AM) sensitivity typically found in children up to 10 years of age reflects an improvement in “processing efficiency” (the central ability to use information extracted by sensory mechanisms). This hypothesis was tested by evaluating temporal integration for AM, a capacity relying on memory and decision factors. This was achieved by measuring the effect of increasing the number of AM cycles (2 vs 8) on AM-detection thresholds for three groups of children aged from 5 to 11 years and a group of young adults. AM-detection thresholds were measured using a forced-choice procedure and sinusoidal AM (4 or 32 Hz rate) applied to a 1024-Hz pure-tone carrier. All age groups demonstrated temporal integration for AM at both rates; that is, significant improvements in AM sensitivity with a higher number of AM cycles. However, an effect of age is observed as both 5-6 year olds and adults exhibited more temporal integration compared to 7-8 and 10-11 year olds at both rates. This difference is due to: (i) the 5-6 year olds displaying the worst thresholds with 2 AM cycles, but similar thresholds with 8 cycles compared to the 7-8 and 10-11 year olds, and, (ii) adults showing the best thresholds with 8 AM cycles but similar thresholds with 2 cycles compared to the 7-8 and 10-11 year olds. Computational modelling indicated that higher levels of internal noise combined with poorer short-term memory capacities in children accounted for the developmental trends. Improvement in processing efficiency may therefore account for the development of AM detection in childhood.

Classification images have become popular tools in psychophysics, yet difficulties associated with their interpretation have often hindered their application. Alternative methods for characterizing perceptual filters have been proposed, and the discussion has often focussed on the degree to which classification images are optimal statistical estimators of system components (e.g. kernels). This technical note argues that those difficulties become irrelevant once the tool is situated within a data-driven interpretational framework. Within this framework, classification images and their nonlinear derivatives are understood not as transparent estimates of system components, but instead as transparent descriptors of data structure. The many pitfalls associated with the former approach, and the power of the latter, are demonstrated via combination of counter-intuitive computer simulations with empirical examples from published literature. A change in perspective over the manner in which this tool is understood and utilized may lead to a more productive engagement with this methodology.

International audience; Each perceptual decision is commonly attached to a judgment of confidence in the uncertainty of that decision. Confidence is classically defined as the estimate of the posterior probability of the decision to be correct, given the evidence. Here we argue that correctness is neither a valid normative statement of what observers should be doing after their perceptual decision nor a proper descriptive statement of what they actually do. Instead, we propose that perceivers aim at being self-consistent with themselves. We present behavioral evidence obtained in two separate psychophysical experiments that human observers achieve that aim. In one experiment adaptation led to aftereffects, and in the other prior stimulus occurrences were manipulated. We show that confidence judgments perfectly follow changes in perceptual reports and response times, regardless of the nature of the bias. Although observers are able to judge the validity of their percepts, they are oblivious to how biased these percepts are. Focusing on self-consistency rather than correctness leads us to interpret confidence as an estimate of the reliability of one's perceptual decision rather than a distance to an unattainable truth.

International audience; How does orienting attention in space affect the quality of our confidence judgments? Orienting attention to a particular location is known to boost visual performance, but the deployment of attention is far from being instantaneous. Whether observers are able to monitor the time needed for attention to deploy remains largely unknown. To address this question, we adapted a “Wundt clocks” paradigm, asking observers (N=140) to reproduce the phase of a rotating clock at the time of an attentional cue, and to evaluate their confidence in their responses. Attention affected the latency between objective and perceived events: the average reported phase was delayed in accordance with the known latencies of voluntary and involuntary attention. Yet, we found that confidence remains oblivious to these attention-induced perceptual delays, like a ‘metacognitive blind spot’. In addition, we observed weaker metacognition specifically during the deployment of voluntary attention, suggesting a tight relationship between the attentional and metacognitive systems. While previous work has considered how visual confidence adjusts to fully attended versus unattended locations, our study demonstrates that the very process of orienting attention in space can alter metacognition.

International audience; Identifying causes solely from observations can be particularly challenging when i) the factors under investigation are difficult to manipulate independently from one-another and ii) observations are high-dimensional. To address this issue, we introduce "Back-to-Back" regression (B2B), a linear method designed to efficiently estimate, from a set of correlated factors, those that most plausibly account for multidimensional observations. First, we prove the consistency of B2B, its links to other linear approaches, and show how it can provide a robust, unbiased and interpretable scalar estimate for each factor. Second, we use a variety of simulated data to show that B2B can outperform forward modeling ("encoding"), backward modeling ("decoding") as well as crossdecomposition modeling (i.e.. canonical correlation analysis and partial least squares) on causal identification when the factors and the observations are not orthogonal. Finally, we apply B2B to a hundred magneto-encephalography recordings and to a hundred functional Magnetic Resonance Imaging recordings acquired while subjects performed a one hour reading task. B2B successfully disentangles the respective contribution of collinear factors such as word length, word frequency in the early visual and late associative cortical responses respectively. B2B compared favorably to other standard techniques on this disentanglement. We discuss how the speed and the generality of B2B sets promising foundations to help identify the causal contributions of covarying factors from high-dimensional observations.

Spectrotemporal modulations (STM) are essential features of speech signals that make them intelligible. While their encoding has been widely investigated in neurophysiology, we still lack a full understanding of how STMs are processed at the behavioral level and how cochlear hearing loss impacts this processing. Here, we introduce a novel methodological framework based on psychophysical reverse correlation deployed in the modulation space to characterize the mechanisms underlying STM detection in noise. We derive perceptual filters for young normal-hearing and older hearing-impaired individuals performing a detection task of an elementary target STM (a given product of temporal and spectral modulations) embedded in other masking STMs. Analyzed with computational tools, our data show that both groups rely on a comparable linear (band-pass)-nonlinear processing cascade, which can be well accounted for by a temporal modulation filter bank model combined with cross-correlation against the target representation. Our results also suggest that the modulation mistuning observed for the hearing-impaired group results primarily from broader cochlear filters. Yet, we find idiosyncratic behaviors that cannot be captured by cochlear tuning alone, highlighting the need to consider variability originating from additional mechanisms. Overall, this integrated experimental-computational approach offers a principled way to assess suprathreshold processing distortions in each individual and could thus be used to further investigate interindividual differences in speech intelligibility.

International audience; The large heterogeneity observed among individuals with similar audiograms for understanding speech in noisy environments still remains poorly understood. Supra-threshold sensory mechanisms, i.e. that operate above detection threshold, likely play a prominent role in these interindividual differences, but a precise view of where and how distortions arise along the auditory processing hierarchy is lacking. Spectrotemporal modulations (STM) - noise signals whose envelope is jointly modulated in time and frequency - offer a unified mathematical framework to probe these supra-threshold processes as they are recruited with speech signals. Yet, at present, it remains unknown how STMs are processed by the human auditory system, and how this processing varies between individuals. In order to provide a clear computational understanding of STM processing for both normal-hearing (NH) and hearing-impaired (HI) individuals, we developed a novel methodological framework that combines psychophysical reverse-correlation experiments deployed in the modulation domain with simulations from current supra-threshold auditory models. In this talk, we will present recent results collected in various tasks where both normal-hearing and hearing-impaired listeners detect or discriminate specific target STMs embedded in other masking STMs. We will show which aspects of their results can be accounted for by frequency selectivity and temporal-envelope based mechanisms, and which cannot, highlighting the need to consider additional mechanisms. Finally, we will discuss how, by focusing on the origins of the variability that remains unaccounted for by these models, this joint experimental-modeling approach could actually be used to pinpoint the peripheral and central components underlying supra-threshold hearing distortions in each individual.

International audience; The precision to locate individual features in depth can often be improved by integrating information over space. However, this integration can sometimes be extremely detrimental, as for example in the case of the Westheimer-McKee phenomenon where features are grouped to form an object. We replicate here the known loss of precision in this phenomenon and document an additional loss of accuracy. These detrimental effects are still present when the object is elicited by other principles of organization, including a cross-modal auditory cue. Similar effects of object formation are found on lateral motion sensitivity. We then present a simple probabilistic model based on the integration of estimated depth within an object and propagation of object mean depth and uncertainty back to the elementary features of the object. This propagation of object uncertainty is a hitherto underestimated side-effect of object formation.

International audience; Humans and animals maintain accurate sound discrimination in the presence of loud sources of background noise. It is commonly assumed that this ability relies on the robustness of auditory cortex responses. However, only a few attempts have been made to characterize neural discrimination of communication sounds masked by noise at each stage of the auditory system and to quantify the noise effects on the neuronal discrimination in terms of alterations in amplitude modulations. Here, we measured neural discrimination between communication sounds masked by a vocalization-shaped stationary noise from multiunit responses recorded in the cochlear nucleus, inferior colliculus, auditory thalamus, and primary and secondary auditory cortex at several signal-to-noise ratios (SNRs) in anesthetized male or female guinea pigs. Masking noise decreased sound discrimination of neuronal populations in each auditory structure, but collicular and thalamic populations showed better performance than cortical populations at each SNR. In contrast, in each auditory structure, discrimination by neuronal populations was slightly decreased when tone-vocoded vocalizations were tested. These results shed new light on the specific contributions of subcortical structures to robust sound encoding, and suggest that the distortion of slow amplitude modulation cues conveyed by communication sounds is one of the factors constraining the neuronal discrimination in subcortical and cortical levels.SIGNIFICANCE STATEMENT Dissecting how auditory neurons discriminate communication sounds in noise is a major goal in auditory neuroscience. Robust sound coding in noise is often viewed as a specific property of cortical networks, although this remains to be demonstrated. Here, we tested the discrimination performance of neuronal populations at five levels of the auditory system in response to conspecific vocalizations masked by noise. In each acoustic condition, subcortical neurons better discriminated target vocalizations than cortical ones and in each structure, the reduction in discrimination performance was related to the reduction in slow amplitude modulation cues.

An outstanding challenge for consciousness research is to characterize the neural signature of conscious access independently of any decisional processes. Here we present a model-based approach that uses inter-trial variability to identify the brain dynamics associated with stimulus processing. We demonstrate that, even in the absence of any task or behavior, the electroencephalographic response to auditory stimuli shows bifurcation dynamics around 250–300 milliseconds post-stimulus. Namely, the same stimulus gives rise to late sustained activity on some trials, and not on others. This late neural activity is predictive of task-related reports, and also of reports of conscious contents that are randomly sampled during task-free listening. Source localization further suggests that task-free conscious access recruits the same neural networks as those associated with explicit report, except for frontal executive components. Studying brain dynamics through variability could thus play a key role for identifying the core signatures of conscious access, independent of report., Current knowledge on the neural basis of consciousness mostly relies on situations where people report their perception. Here, the authors provide evidence for the idea that bifurcation in brain dynamics reflects conscious perception independent of report.

SummaryHumans engagement in music rests on underlying elements such as the listeners’ cultural background and general interest in music, all shaping the way music is processed in the brain and perceived. Crucially, these factors modulate how listeners anticipate musical events, a process inducing instantaneous neural responses as the music confronts these expectations. Measuring such neural correlates would represent a direct window into high-level brain processing of music. Here we recorded electroencephalographic and electrocorticographic brain responses as participants listened to Bach melodies. We assessed the relative contributions of the acoustic versus melodic components of the music to the neural signal. Acoustic features included envelope and its derivative. Melodic features included information on melodic progressions (pitch) and their tempo (onsets), which were extracted from a Markov model predicting the next note based on a corpus of Western music and the preceding proximal musical context. We related the music to brain activity with a linear temporal response function, and demonstrated that cortical responses to music encode melodic expectations. Specifically, individual-subject neural signals were better predicted by a combination of acoustic and melodic expectation features than by either alone. This effect was most pronounced at response latencies up to 350ms, and in both planum temporale and Heschl’s gyrus. Finally, expectations of pitch and onset-time of musical notes exerted independent cortical effects, and such influences were modulated by the listeners’ musical expertise. Overall, this study demonstrates how the interplay of experimental and theoretical approaches can yield novel insights into the cortical encoding of melodic expectations.

International audience; Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder causing a progressive motor weakness of all voluntary muscles, whose progression challenges communication modalities such as handwriting or speech. The current study investigated whether ALS subjects can use Eye-On-Line (EOL), a novel eye-operated communication device allowing, after training, to voluntarily control smooth-pursuit eye-movements (SPEM) so as to eye-write in cursive. To that aim, ALS participants (n = 12) with preserved eye-movements but impaired handwriting were trained during six on-site visits. The primary outcome of the study was the recognition of eye-written digits (0-9) from ALS and healthy control subjects by naïve "readers." Changes in oculomotor performance and the safety of EOL were also evaluated. At the end of the program, 69.4% of the eye-written digits from 11 ALS subjects were recognized by naïve readers, similar to the 67.3% found for eye-written digits from controls participants, with however, large inter-individual differences in both groups of "writers." Training with EOL was associated with a transient fatigue leading one ALS subject to drop out the study at the fifth visit. Otherwise, itching eyes was the most common adverse event (3 subjects). This study shows that, despite the impact of ALS on the motor system, most ALS participants could improve their mastering of eye-movements, so as to produce recognizable eye-written digits, although the eye-traces sometimes needed smoothing to ease digit legibility from both ALS subjects and control participants. The capability to endogenously and voluntarily generate eye-traces using EOL brings a novel way to communicate for disabled individuals, allowing creative personal and emotional expression.

Between 1 to 5 out of 100 people worldwide has never experienced normotypic vision due to a condition called amblyopia, and about 1 out of 4000 suffer from inherited retinal dystrophies that progressively lead them to blindness. While a wide range of technologies and therapies are being developed to restore vision, a fundamental question still remains unanswered: would the adult visual brain retain a sufficient plastic potential to learn how to see after a prolonged period of abnormal visual experience? In this review we summarize studies showing that the visual brain of sighted adults retains a type of developmental plasticity, called homeostatic plasticity, and this property has been recently exploited successfully for adult amblyopia recover. Next, we discuss how the brain circuits reorganizes when visual stimulation is partially restored by means of a bionic eye in late blinds with Retinitis Pigmentosa. The primary visual cortex in these patients slowly became activated by the artificial visual stimulation, indicating that sight restoration therapies can rely on a considerable degree of spared plasticity in adulthood., 28 pages, 2 figures

The ability to recognize many sounds in everyday soundscapes is a useful and impressive feature of auditory perception in which timbre likely plays a key role. This chapter discusses what is known of timbre in the context of sound source recognition. It first surveys the methodologies that have been used to characterize a listener’s ability to recognize sounds and then examines the types of acoustic cues that could underlie the behavioral findings. In some studies, listeners were directly asked to recognize familiar sounds or versions of them that were truncated, filtered, or distorted by other resynthesis methods that preserved some cues but not others. In other studies, listeners were exposed to novel sounds, and the build-up of cues over time or the learning of new cues was tracked. The evidence currently available raises an interesting debate that can be articulated around two qualitatively different hypotheses: Are sounds recognized through distinctive features unique to each sound category (but of which there would need to be many to cover all recognized categories) or rather, are sounds recognized through a relatively small number of perceptual dimensions in which different sounds have their own recognizable position?

International audience; Sentence comprehension requires inferring, from a sequence of words, the structure of syntactic relationships that bind these words into a semantic representation. Our limited ability to build some specific syntactic structures, such as nested center-embedded clauses (e.g., “The dog that the cat that the mouse bit chased ran away”), suggests a striking capacity limitation of sentence processing, and thus offers a window to understand how the human brain processes sentences. Here, we review the main hypotheses proposed in psycholinguistics to explain such capacity limitation. We then introduce an alternative approach, derived from our recent work on artificial neural networks optimized for language modeling, and predict that capacity limitation derives from the emergence of sparse and feature-specific syntactic units. Unlike psycholinguistic theories, our neural network-based framework provides precise capacity-limit predictions without making any a priori assumptions about the form of the grammar or parser. Finally, we discuss how our framework may clarify the mechanistic underpinning of language processing and its limitations in the human brain.

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International audience; Filters are commonly used to reduce noise and improve data quality. Filter theory is part of a scientist's training, yet the impact of filters on interpreting data is not always fully appreciated. This paper reviews the issue, explains what is a filter, what problems are to be expected when using them, how to choose the right filter, or how to avoid filtering by using alternative tools. Time-frequency analysis shares some of the same problems that filters have, particularly in the case of wavelet transforms. We recommend reporting filter characteristics with sufficient details, including a plot of the impulse or step response as an inset.

The effect of the number of modulation cycles (N) on frequency-modulation (FM) detection thresholds (FMDTs) was measured with and without interfering amplitude modulation (AM) for hearing-impaired (HI) listeners, using a 500-Hz sinusoidal carrier and FM rates of 2 and 20 Hz. The data were compared with FMDTs for normal-hearing (NH) listeners and AM detection thresholds (AMDTs) for NH and HI listeners [Wallaert, Moore, and Lorenzi (2016). J. Acoust. Soc. 139, 3088–3096; Wallaert, Moore, Ewert, and Lorenzi (2017). J. Acoust. Soc. 141, 971–980]. FMDTs were higher for HI than for NH listeners, but the effect of increasing N was similar across groups. In contrast, AMDTs were lower and the effect of increasing N was greater for HI listeners than for NH listeners. A model of temporal-envelope processing based on a modulation filter-bank and a template-matching decision strategy accounted better for the FMDTs at 20 Hz than at 2 Hz for young NH listeners and predicted greater temporal integration of FM than observed for all groups. These results suggest that different mechanisms underlie AM and FM detection at low rates and that hearing loss impairs FM-detection mechanisms, but preserves the memory and decision processes responsible for temporal integration of FM.The effect of the number of modulation cycles (N) on frequency-modulation (FM) detection thresholds (FMDTs) was measured with and without interfering amplitude modulation (AM) for hearing-impaired (HI) listeners, using a 500-Hz sinusoidal carrier and FM rates of 2 and 20 Hz. The data were compared with FMDTs for normal-hearing (NH) listeners and AM detection thresholds (AMDTs) for NH and HI listeners [Wallaert, Moore, and Lorenzi (2016). J. Acoust. Soc. 139, 3088–3096; Wallaert, Moore, Ewert, and Lorenzi (2017). J. Acoust. Soc. 141, 971–980]. FMDTs were higher for HI than for NH listeners, but the effect of increasing N was similar across groups. In contrast, AMDTs were lower and the effect of increasing N was greater for HI listeners than for NH listeners. A model of temporal-envelope processing based on a modulation filter-bank and a template-matching decision strategy accounted better for the FMDTs at 20 Hz than at 2 Hz for young NH listeners and predicted greater temporal integration of FM than observ...

International audience; An auditory illusion caught the world’s attention recently. For the same noisy speech utterance, different people reported hearing either ‘Laurel’ or ‘Yanny’. The dichotomy highlights how perceptions are inferences from inherently ambiguous sensory information, even though ambiguity is often unnoticed.

Frequency modulation (FM) is a common acoustic feature of natural sounds and is known to play a role in robust sound source recognition. Auditory neurons show precise stimulus-synchronized discharge patterns that may be used for the representation of low-rate FM. However, it remains unclear whether this representation is based on synchronization to slow temporal envelope (ENV) cues resulting from cochlear filtering or phase locking to faster temporal fine structure (TFS) cues. To investigate the plausibility of those encoding schemes, single units of the ventral cochlear nucleus of guinea pigs of either sex were recorded in response to sine FM tones centered at the unit's best frequency (BF). The results show that, in contrast to high-BF units, for modulation depths within the receptive field, low-BF units (in vivodata also reveal a high level of diversity in responses across unit types. TFS cues are mainly conveyed by low-frequency and primary-like units and ENV cues by chopper and onset units. The diversity of responses exhibited by cochlear nucleus neurons provides a neural basis for a dual-coding scheme of FM in the brainstem based on both ENV and TFS cues.SIGNIFICANCE STATEMENTNatural sounds, including speech, convey informative temporal modulations in frequency. Understanding how the auditory system represents those frequency modulations (FM) has important implications as robust sound source recognition depends crucially on the reception of low-rate FM cues. Here, we recorded 115 single-unit responses from the ventral cochlear nucleus in response to FM and provide the first physiological evidence of a dual-coding mechanism of FM via synchronization to temporal envelope cues and phase locking to temporal fine structure cues. We also demonstrate a diversity of neural responses with different coding specializations. These results support the dual-coding scheme proposed by psychophysicists to account for FM sensitivity in humans and provide new insights on how this might be implemented in the early stages of the auditory pathway.

International audience; The global loudness of a varying intensity sound is greater when the intensity increases than when it decreases. This global loudness asymmetry was found to be larger for pure tones than for broadband noises. In this study, our aim was to determine whether this difference between pure tones and noises is due to the difference in bandwidth between sounds or to the difference in the strength of the sensation of pitch. The loudness asymmetry was measured for broadband and for narrow-band signals that do or do not elicit a sensation of pitch. The asymmetry was greater for sounds that elicit a sensation of pitch whatever their bandwidth. The loudness model for time varying sounds [1] predicted well the asymmetry for the broadband noise that does not elicit a sensation of pitch and for a multi-tonal sound. For the other sounds the asymmetry was greater than predicted. It is known that loudness and pitch interact. The difference in asymmetry between sounds that elicit pitch and sounds that do not elicit pitch might be due to this interaction.

N.F. was an EPFL fellow co-funded by Marie Skłodowska-Curie. C.L. was funded by the project ECSPLAIN (European Research Council under the Seventh Framework Programme, FPT/2007-2013, grant agreement no. 338866). A.A. was a Blavatnik fellow and a Royal society Kohn international fellow. We thank the Association for the Scientific Study of Consciousness for travel funding, and we are grateful to Liad Mudrik, Lavi Secundo, Andrés Canales-Johnson, and Ophelia Deroy for valuable discussions and helpful comments on the article.; International audience; Over the last 30 years, our understanding of the neurocognitive bases of consciousness has improved, mostly through studies employing vision. While studying consciousness in the visual modality presents clear advantages, we believe that a comprehensive scientific account of subjective experience must not neglect other exteroceptive and interoceptive signals as well as the role of multisensory interactions for perceptual and self-consciousness. Here, we briefly review four distinct lines of work which converge in documenting how multisensory signals are processed across several levels and contents of consciousness. Namely, how multisensory interactions occur when consciousness is prevented because of perceptual manipulations (i.e. subliminal stimuli) or because of low vigilance states (i.e. sleep, anesthesia), how interactions between exteroceptive and interoceptive signals give rise to bodily self-consciousness, and how multisensory signals are combined to form metacognitive judgments. By describing the interactions between multisensory signals at the perceptual, cognitive, and metacognitive levels, we illustrate how stepping out the visual comfort zone may help in deriving refined accounts of consciousness, and may allow cancelling out idiosyncrasies of each sense to delineate supramodal mechanisms involved during consciousness.

Sleep and memory are deeply related, but the nature of the neuroplastic processes induced by sleep remains unclear. Here, we report that memory traces can be both formed or suppressed during sleep, depending on sleep phase. We played samples of acoustic noise to sleeping human listeners. Repeated exposure to a novel noise during Rapid Eye Movements (REM) or light non-REM (NREM) sleep leads to improvements in behavioral performance upon awakening. Strikingly, the same exposure during deep NREM sleep leads to impaired performance upon awakening. Electroencephalographic markers of learning extracted during sleep confirm a dissociation between sleep facilitating memory formation (light NREM and REM sleep) and sleep suppressing learning (deep NREM sleep). We can trace these neural changes back to transient sleep events, such as spindles for memory facilitation and slow waves for suppression. Thus, highly selective memory processes are active during human sleep, with intertwined episodes of facilitative and suppressive plasticity., Though memory and sleep are related, it is still unclear whether new memories can be formed during sleep. Here, authors show that people could learn new sounds during REM or light non-REM sleep, but that learning was suppressed when sounds were played during deep NREM sleep.

Supplemental Digital Content is available in the text, It remains unclear whether children and adolescents in the child welfare system (CWS) exhibit a higher prevalence of mental disorders compared with the general population. The objective of this study was to perform a systematic review and meta-analysis to assess the prevalence of mental disorders in the CWS. All of the epidemiological surveys assessing the prevalence of mental disorders in children and adolescents in the CWS were included. The pooled prevalence was estimated with random effect models. Potential sources of heterogeneity were explored using meta-regression analyses. Eight studies provided prevalence estimates that were obtained from 3104 children and adolescents. Nearly 1 child or adolescent of every 2 (49%; 95% confidence interval (CI) 43–54) was identified as meeting criteria for a current mental disorder. The most common mental disorder was disruptive disorder (27%; 95% CI 20–34), including conduct disorder (20%; 95% CI 13–27) and oppositional defiant disorder (12%; 95% CI 10–14). The prevalence of attention-deficit/hyperactivity disorder was estimated to be 11% (95% CI 6–15). The prevalence estimates of anxiety and depressive disorders were 18% (95% CI 12–24) and 11% (95% CI 7–15). Posttraumatic stress disorder had the lowest prevalence (4%; 95% CI 2–6). High prevalences of mental disorders in the CWS were reported, which highlights the need for the provision of qualified service. The substantial heterogeneity of our findings is indicative of the need for accurate epidemiological data to effectively guide public policy.

International audience; BACKGROUND: The use of analgesics can lead to cases of drug abuse and dependence. It can also cause pseudo-addiction in patients suffering from pain. What is the actual situation in patients suffering from severe sickle-cell disease, exposed to acute pain during vaso-occlusive crises? Evaluation of the use of analgesics, on the basis of Diagnostic and Statistical Manual of Mental Disorders criteria for substance abuse and dependence, makes it possible to differentiate the symptoms occurring only in a context of pain, in the aim of managing the pain, and thus describing pseudo-addiction, from symptoms also occurring when there is no pain, and more in favour of true addiction. Currently there is no data available in France on this problem, and no studies have been carried out in children or adolescents with sickle-cell disease. The purpose of the study is to evaluate the prevalence of problematic use of equimolar mixture of oxygen and nitrous oxide and other analgesic drugs in a population of subjects with severe sickle-cell disease in France. METHODS/DESIGN: PHEDRE (Pharmacodépendance Et DREpanocytose-drug dependence and sickle-cell disease) is an observational, descriptive and transversal study. Patients under the age of 26 with sickle-cell disease are included in the study by the doctors looking after them in sickle-cell disease centres. The patients are then contacted by a trained researcher for a telephone interview, including an evaluation of the Diagnostic and Statistical Manual of Mental Disorders criteria for abuse and dependence to equimolar mixture of oxygen and nitrous oxide and for each of the analgesic drugs taken by the patient. The data are also completed using the subject's medical record. DISCUSSION: This study will make it possible to provide an initial quantitative and qualitative evaluation of problematic use of equimolar mixture of oxygen and nitrous oxide and analgesic drugs in the sickle-cell disease population. The results will be used firstly to provide additional data essential for monitoring the risk of overdose, abuse, dependence and misuse of these products, and to begin awareness-raising and to provide information for health care professionals, in order to significantly improve the management of sickle-cell disease-related pain. TRIAL REGISTRATION: Clinical Trials.gov ID: NCT02580565 registered 16 October 2015 Unique Protocol ID: RC14\₀344.

International audience; (2015) The perception of speech modulation cues in lexical tones is guided by early language-specific experience. Front. Psychol. 6:1290. A number of studies showed that infants reorganize their perception of speech sounds according to their native language categories during their first year of life. Still, information is lacking about the contribution of basic auditory mechanisms to this process. This study aimed to evaluate when native language experience starts to noticeably affect the perceptual processing of basic acoustic cues [i.e., frequency-modulation (FM) and amplitude-modulation information] known to be crucial for speech perception in adults. The discrimination of a lexical-tone contrast (rising versus low) was assessed in 6-and 10-month-old infants learning either French or Mandarin using a visual habituation paradigm. The lexical tones were presented in two conditions designed to either keep intact or to severely degrade the FM and fine spectral cues needed to accurately perceive voice-pitch trajectory. A third condition was designed to assess the discrimination of the same voice-pitch trajectories using click trains containing only the FM cues related to the fundamental-frequency (F0) in French-and Mandarin-learning 10-month-old infants. Results showed that the younger infants of both language groups and the Mandarin-learning 10-month-olds discriminated the intact lexical-tone contrast while French-learning 10-month-olds failed. However, only the French 10-month-olds discriminated degraded lexical tones when FM, and thus voice-pitch cues were reduced. Moreover, Mandarin-learning 10-month-olds were found to discriminate the pitch trajectories as presented in click trains better than French infants. Altogether, these results reveal that the perceptual reorganization occurring during the first year of life for lexical tones is coupled with changes in the auditory ability to use speech modulation cues.

International audience; The timbre of a sound plays an important role in our ability to discriminate between behaviorally relevant auditory categories, such as different vowels in speech. Here, we investigated, in the primary auditory cortex (A1) of anesthetized guinea pigs, the neural representation of vowels with impoverished timbre cues. Five different vowels were presented with durations ranging from 2 to 128 ms. A psychophysical experiment involving human listeners showed that identification performance was near ceiling for the longer durations and degraded close to chance level for the shortest durations. This was likely due to spectral splatter, which reduced the contrast between the spectral profiles of the vowels at short durations. Effects of vowel duration on cortical responses were well predicted by the linear frequency responses of A1 neurons. Using mutual information, we found that auditory cortical neurons in the guinea pig could be used to reliably identify several vowels for all durations. Information carried by each cortical site was low on average, but the population code was accurate even for durations where human behavioral performance was poor. These results suggest that a place population code is available at the level of A1 to encode spectral profile cues for even very short sounds.

International audience; The growing availability of large, multidimensional data sets has created demand for high-performance, interactive visualization tools. VisPy leverages the GPU to provide fast, interactive, and beautiful visualizations in a high-level API. Here we introduce the main features, architecture, and techniques used in VisPy.

Purpose This study assessed the role of spectro-temporal modulation cues in the discrimination of 2 phonetic contrasts (voicing and place) for young infants. Method A visual-habituation procedure was used to assess the ability of French-learning 6-month-old infants with normal hearing to discriminate voiced versus unvoiced (/aba/-/apa/) and labial versus dental (/aba/-/ada/) stop consonants. The stimuli were processed by tone-excited vocoders to degrade frequency-modulation cues while preserving: (a) amplitude-modulation (AM) cues within 32 analysis frequency bands, (b) slow AM cues only ( Results Infants exhibited discrimination responses for both phonetic contrasts in each processing condition. However, when fast AM cues were degraded, infants required a longer exposure to vocoded stimuli to reach the habituation criterion. Conclusions Altogether, these results indicate that the processing of modulation cues conveying phonetic information on voicing and place is “functional” at 6 months. The data also suggest that the perceptual weight of fast AM speech cues may change during development.

Accuracy in estimating an object’s global motion over time is not only affected by the noise in visual motion information but also by the spatial limitation of the local motion analyzers (aperture problem). Perceptual and oculomotor data demonstrate that during the initial stages of the motion information processing, 1D motion cues related to the object’s edges have a dominating influence over the estimate of the object’s global motion. However, during the later stages, 2D motion cues related to terminators (edge-endings) progressively take over, leading to a final correct estimate of the object’s global motion. Here, we propose a recursive extension to the Bayesian framework for motion processing ( Weiss, Simoncelli, & Adelson, 2002 ) cascaded with a model oculomotor plant to describe the dynamic integration of 1D and 2D motion information in the context of smooth pursuit eye movements. In the recurrent Bayesian framework, the prior defined in the velocity space is combined with the two independent measurement likelihood functions, representing edge-related and terminator-related information, respectively to obtain the posterior. The prior is updated with the posterior at the end of each iteration step. The maximum-a posteriori (MAP) of the posterior distribution at every time step is fed into the oculomotor plant to produce eye velocity responses that are compared to the human smooth pursuit data. The recurrent model was tuned with the variance of pursuit responses to either “pure” 1D or “pure” 2D motion. The oculomotor plant was tuned with an independent set of oculomotor data, including the effects of line length (i.e. stimulus energy) and directional anisotropies in the smooth pursuit responses. The model not only provides an accurate qualitative account of dynamic motion integration but also a quantitative account that is close to the smooth pursuit response across several conditions (three contrasts and three speeds) for two human subjects.