Stages Of Auditory Processing Research Articles

Absolute Pitch: Evidence for Early Cognitive Facilitation during Passive Listening as Revealed by Reduced P3a Amplitudes

Absolute pitch (AP) is the rare ability to identify or produce different pitches without using reference tones. At least two sequential processing stages are assumed to contribute to this phenomenon. The first recruits a pitch memory mechanism at an early stage of auditory processing, whereas the second is driven by a later cognitive mechanism (pitch labeling). Several investigations have used active tasks, but it is unclear how these two mechanisms contribute to AP during passive listening. The present work investigated the temporal dynamics of tone processing in AP and non-AP (NAP) participants by using EEG. We applied a passive oddball paradigm with between- and within-tone category manipulations and analyzed the MMN reflecting the early stage of auditory processing and the P3a response reflecting the later cognitive mechanism during the second processing stage. Results did not reveal between-group differences in MMN waveforms. By contrast, the P3a response was specifically associated with AP and sensitive to the processing of different pitch types. Specifically, AP participants exhibited smaller P3a amplitudes, especially in between-tone category conditions, and P3a responses correlated significantly with the age of commencement of musical training, suggesting an influence of early musical exposure on AP. Our results reinforce the current opinion that the representation of pitches at the processing level of the auditory-related cortex is comparable among AP and NAP participants, whereas the later processing stage is critical for AP. Results are interpreted as reflecting cognitive facilitation in AP participants, possibly driven by the availability of multiple codes for tones.

Different forms of effective connectivity in primate frontotemporal pathways.

It is generally held that non-primary sensory regions of the brain have a strong impact on frontal cortex. However, the effective connectivity of pathways to frontal cortex is poorly understood. Here we microstimulate sites in the superior temporal and ventral frontal cortex of monkeys and use functional magnetic resonance imaging to evaluate the functional activity resulting from the stimulation of interconnected regions. Surprisingly, we find that, although certain earlier stages of auditory cortical processing can strongly activate frontal cortex, downstream auditory regions, such as voice-sensitive cortex, appear to functionally engage primarily an ipsilateral temporal lobe network. Stimulating other sites within this activated temporal lobe network shows strong activation of frontal cortex. The results indicate that the relative stage of sensory processing does not predict the level of functional access to the frontal lobes. Rather, certain brain regions engage local networks, only parts of which have a strong functional impact on frontal cortex.

Brainstem encoding of speech and musical stimuli in congenital amusia: evidence from Cantonese speakers.

Congenital amusia is a neurodevelopmental disorder of musical processing that also impacts subtle aspects of speech processing. It remains debated at what stage(s) of auditory processing deficits in amusia arise. In this study, we investigated whether amusia originates from impaired subcortical encoding of speech (in quiet and noise) and musical sounds in the brainstem. Fourteen Cantonese-speaking amusics and 14 matched controls passively listened to six Cantonese lexical tones in quiet, two Cantonese tones in noise (signal-to-noise ratios at 0 and 20 dB), and two cello tones in quiet while their frequency-following responses (FFRs) to these tones were recorded. All participants also completed a behavioral lexical tone identification task. The results indicated normal brainstem encoding of pitch in speech (in quiet and noise) and musical stimuli in amusics relative to controls, as measured by FFR pitch strength, pitch error, and stimulus-to-response correlation. There was also no group difference in neural conduction time or FFR amplitudes. Both groups demonstrated better FFRs to speech (in quiet and noise) than to musical stimuli. However, a significant group difference was observed for tone identification, with amusics showing significantly lower accuracy than controls. Analysis of the tone confusion matrices suggested that amusics were more likely than controls to confuse between tones that shared similar acoustic features. Interestingly, this deficit in lexical tone identification was not coupled with brainstem abnormality for either speech or musical stimuli. Together, our results suggest that the amusic brainstem is not functioning abnormally, although higher-order linguistic pitch processing is impaired in amusia. This finding has significant implications for theories of central auditory processing, requiring further investigations into how different stages of auditory processing interact in the human brain.

Repetition suppression and repetition enhancement underlie auditory memory-trace formation in the human brain: an MEG study

The formation of echoic memory traces has traditionally been inferred from the enhanced responses to its deviations. The mismatch negativity (MMN), an auditory event-related potential (ERP) elicited between 100 and 250ms after sound deviation is an indirect index of regularity encoding that reflects a memory-based comparison process. Recently, repetition positivity (RP) has been described as a candidate ERP correlate of direct memory trace formation. RP consists of repetition suppression and enhancement effects occurring in different auditory components between 50 and 250ms after sound onset. However, the neuronal generators engaged in the encoding of repeated stimulus features have received little interest. This study intends to investigate the neuronal sources underlying the formation and strengthening of new memory traces by employing a roving-standard paradigm, where trains of different frequencies and different lengths are presented randomly. Source generators of repetition enhanced (RE) and suppressed (RS) activity were modeled using magnetoencephalography (MEG) in healthy subjects. Our results show that, in line with RP findings, N1m (~95–150ms) activity is suppressed with stimulus repetition. In addition, we observed the emergence of a sustained field (~230–270ms) that showed RE. Source analysis revealed neuronal generators of RS and RE located in both auditory and non-auditory areas, like the medial parietal cortex and frontal areas. The different timing and location of neural generators involved in RS and RE points to the existence of functionally separated mechanisms devoted to acoustic memory-trace formation in different auditory processing stages of the human brain.

Layer Specific Sharpening of Frequency Tuning by Selective Attention in Primary Auditory Cortex

Recent electrophysiological and neuroimaging studies provide converging evidence that attending to sounds increases the response selectivity of neuronal ensembles even at the first cortical stage of auditory stimulus processing in primary auditory cortex (A1). This is achieved by enhancement of responses in the regions that process attended frequency content, and by suppression of responses in the surrounding regions. The goals of our study were to define the extent to which A1 neuronal ensembles are involved in this process, determine its effect on the frequency tuning of A1 neuronal ensembles, and examine the involvement of the different cortical layers. To accomplish these, we analyzed laminar profiles of synaptic activity and action potentials recorded in A1 of macaques performing a rhythmic intermodal selective attention task. We found that the frequency tuning of neuronal ensembles was sharpened due to both increased gain at the preferentially processed or best frequency and increased response suppression at all other frequencies when auditory stimuli were attended. Our results suggest that these effects are due to a frequency-specific counterphase entrainment of ongoing delta oscillations, which predictively orchestrates opposite sign excitability changes across all of A1. This results in a net suppressive effect due to the large proportion of neuronal ensembles that do not specifically process the attended frequency content. Furthermore, analysis of laminar activation profiles revealed that although attention-related suppressive effects predominate the responses of supragranular neuronal ensembles, response enhancement is dominant in the granular and infragranular layers, providing evidence for layer-specific cortical operations in attentive stimulus processing.

Auditory selective attention in adolescents with major depression: An event-related potential study

BackgroundMajor depression (MD) is associated with deficits in selective attention. Previous studies in adults with MD using event-related potentials (ERPs) reported abnormalities in the neurophysiological correlates of auditory selective attention. However, it is yet unclear whether these findings can be generalized to MD in adolescence. Thus, the aim of the present ERP study was to explore the neural mechanisms of auditory selective attention in adolescents with MD. Methods24 male and female unmedicated adolescents with MD and 21 control subjects were included in the study. ERPs were collected during an auditory oddball paradigm. ResultsDepressive adolescents tended to show a longer N100 latency to target and non-target tones. Moreover, MD subjects showed a prolonged latency of the P200 component to targets. Across groups, longer P200 latency was associated with a decreased tendency of disinhibited behavior as assessed by a behavioral questionnaire. LimitationsTo be able to draw more precise conclusions about differences between the neural bases of selective attention in adolescents vs. adults with MD, future studies should include both age groups and apply the same experimental setting across all subjects. ConclusionsThe study provides strong support for abnormalities in the neurophysiolgical bases of selective attention in adolecents with MD at early stages of auditory information processing. Absent group differences in later ERP components reflecting voluntary attentional processes stand in contrast to results reported in adults with MD and may suggest that adolescents with MD possess mechanisms to compensate for abnormalities in the early stages of selective attention.

Modulation of Auditory Motion Processing by Visual Motion

Neurophysiological findings suggested that auditory and visual motion information is integrated at an early stage of auditory cortical processing, already starting in primary auditory cortex. Here, the effect of visual motion on processing of auditory motion was investigated by employing electrotomography in combination with free-field sound motion. A delayed-motion paradigm was used in which the onset of motion was delayed relative to the onset of an initially stationary stimulus. The results indicated that activity related to the motion-onset response, a neurophysiological correlate of auditory motion processing, interacts with the processing of visual motion at quite early stages of auditory analysis in the dimensions of both the time and the location of cortical processing. A modulation of auditory motion processing by concurrent visual motion was found already around 170 ms after motion onset (cN1 component) in the regions of primary auditory cortex and posterior superior temporal gyrus: Incongruent visual motion enhanced the auditory motion onset response in auditory regions ipsilateral to the sound motion stimulus, thus reducing the pattern of contralaterality observed with unimodal auditory stimuli. No modulation was found in parietal cortex nor around 250 ms after motion onset (cP2 component) in any auditory region of interest. These findings may reflect the integration of auditory and visual motion information in low-level areas of the auditory cortical system at relatively early points in time.

Perception of prosody in normal and whispered French.

The current study explored perception of prosody in normal and whispered speech using a two-interval, two-alternative forced-choice psychophysical task where listeners discriminated between French noun phrases pronounced as declaratives or interrogatives. Stimuli were either presented between 50 and 8000 Hz or filtered into one of three broad frequency regions, corresponding to harmonic-resolvability regions for normal speech (resolved, partially resolved, unresolved harmonics). Normal speech was presented against a speech-shaped noise masker, whereas whispered speech was presented in quiet. The results showed that discrimination performance was differentially affected by filtering for normal and whispered speech, suggesting that cues to prosody differ between speech modes. For whispered speech, evidence was mainly derived from the high-frequency region, whereas for normal speech, evidence was mainly derived from the low-frequency (resolved harmonics) region. Modeling of the early stages of auditory processing confirmed that for whispered speech, perception of prosody was not based on temporal auditory cues and suggests that listeners may rely on place of excitation (spectral) cues that are, in contrast with suggestions made by earlier work, distributed across the spectrum.

Early Attentional Modulation of the Neural Network Evoked with the Auditory Paired-click Paradigm: An MEG Study

Although numerous research studies have explored the functional attributes of the human duration perception, the spatio- temporal information on cortical networks underlying this process is still an open question. Moreover, the issue of possible differences in the nature of timing mechanisms responsible for perception of sub- and supra-second intervals requires the implementation of the functional brain imaging techniques with both high spatial and temporal resolution. Attention is very frequently used as a modulating factor for the perceived duration of a sensory stimulus. The non-attended stimuli appear to last shorter than the attended ones, increasing the perceived duration of a concurrent stimulus (Gorea, 2011). This study challenges the accepted model of early sensory responses, activated during the first 100ms after stimulus presentation, as preattentive, automatic processes which modulate the neural sensitivity to incoming stimuli (gating phenomena). We utilized Elekta Neuromag 306-channel whole-head system for magnetoencephalography (MEG) measurements and multi-dipole Calibrated Start Spatio Temporal (CSST) localization technique (Ranken et al., 2002) to investigate whether voluntary attention directed at the second tone of a pair in the standard paired-click paradigm could affect cortical networks underlying the gating out phenomenon. MEG recordings were obtained in a magnetically shielded room at the Biomagnetic Center in Jena, Germany. Two consecutive (ISI=500ms) identical short tonnes (S1 and S2; duration=20ms; f=1200Hz; ITI=8±1s) were used to evoke standard gating cortical responses in 19 healthy participants (21-38 years). In the second condition, the task was to direct attention toward the second tone and to respond to a rarely presented non-identical second tone of the pair (R=1300Hz, p(S1R)=0.3). MEG recordings showed transient early and middle latency responses with peak amplitudes over the temporo-parietal sensors followed by a peak of a sustained activity. Less prominent transient activity was recorded over the frontal sensors, accompanied with a more steady- state component from 100 until 400ms post-stimulus for both conditions. Preliminary results of the CSST spatio-temporal analyses revealed 4-6 brain regions activated during 20-500ms time interval including bilateral superior temporal gyrus (STG), bilateral and medial prefrontal (PF), bilateral parietal (PA) regions, and central motor cortex area. A cortical source underlying the steady-state component was identified in the left prefrontal region for S1 tone, and in central posterior regions (PA) for the repeated tone S2. During the standard paradigm the M50 gating suppression was observed only for bilateral STG sources while bilateral PF and PA sources did not show any reduction in the response during the first 100ms post-stimulus. Targeting the attention towards the second tone enhanced the M50 amplitude of the bilateral STG responses in respect to the repeated stimulus S2 and caused a change in the activated network evident by the emergence of a new generator in the medial PF area (orbitofrontal) instead of dorsolateral PF generators evoked in non-attended condition. These results demonstrate that voluntary attention can exert a topological and functional modulatory influence on the neural network even during early stages of auditory processing.

Effects of remifentanil on processing of auditory stimuli: A combined MEG/EEG study

Remifentanil (Ultiva(®)) is a potent ultra-short acting mu-opioid receptor agonist used for perioperative pain treatment and anaesthesia. So far, it is not known how sensitive the cognitive processing of auditory perception elicited by the mismatch negativity (MMN) paradigm is to opioids. The present exploratory study investigated how the opioid remifentanil modulates different stages of auditory processing as reflected in the MMN(m) and P3a(m). We recorded electroencephalography (EEG) and magnetoencephalography (MEG) during auditory stimulation under remifentanil or placebo infusion in 20 healthy participants. For the MMN, a gender effect was found for tones deviating in frequency (± 10%) from the standard tone. Remifentanil increased the amplitude of the frequency MMN at F3 in females but not in males. No effect of treatment was found for the MMN(m) or the novel P3a(m). These results suggest that while the bottom-up stimulus change detection system for auditory stimuli appears to be relatively insensitive to opioids, the automatic attention switch caused by the change detection seems to be modulated by the opioid system in females. The multiple deviant paradigm including novel sounds is a promising tool for investigating pharmacological manipulation of different stages of auditory processing. Furthermore, combining the two techniques will yield more specific information about the drug effects on MMN(m).

Central dysmyelination reduces the temporal fidelity of synaptic transmission and the reliability of postsynaptic firing during high-frequency stimulation

Auditory brain stem circuits rely on fast, precise, and reliable neurotransmission to process auditory information. To determine the fundamental role of myelination in auditory brain stem function, we examined the evoked auditory brain stem response (ABR) from the Long Evans shaker (LES) rat, which lacks myelin due to a genetic deletion of myelin basic protein. In control rats, the ABR evoked by a click consisted of five well-defined waves (denoted waves I-V). In LES rats, waves I, IV, and V were present, but waves II and III were undetectable, indicating disrupted function in the earliest stages of central nervous system auditory processing. In addition, the developmental shortening of the interval between waves I and IV that normally occurs in control rats was arrested and resulted in a significant increase in the central conduction time in LES rats. In brain stem slices, action potential transmission between the calyx of Held terminals and the medial nucleus of the trapezoid body (MNTB) neurons was delayed and less reliable in LES rats, although the resting potential, threshold, input resistance, and length of the axon initial segment of the postsynaptic MNTB neurons were normal. The amplitude of glutamatergic excitatory postsynaptic currents (EPSCs) and the degree of synaptic depression during high-frequency stimulation were not different between LES rats and controls, but LES rats exhibited a marked slow component to the EPSC decay and a much higher rate of presynaptic failures. Together, these results indicate that loss of myelin disrupts brain stem auditory processing, increasing central conduction time and reducing the reliability of neurotransmission.

Discrimination of personally significant from nonsignificant sounds: A training study

Discriminating personally significant from nonsignificant sounds is of high behavioral relevance and appears to be performed effortlessly outside of the focus of attention. Although there is no doubt that we automatically monitor our auditory environment for unexpected, and hence potentially significant, events, the characteristics of detection mechanisms based on individual memory schemata have been far less explored. The experiments in the present study were designed to measure event-related potentials (ERPs) sensitive to the discrimination of personally significant and nonsignificant nonlinguistic sounds. Participants were presented with random sequences of acoustically variable sounds, one of which was associated with personal significance for each of the participants. In Experiment 1, each participant's own mobile SMS ringtone served as his or her significant sound. In Experiment 2, a nonsignificant sound was instead trained to become personally significant to each participant over a period of one month. ERPs revealed differential processing of personally significant and nonsignificant sounds from about 200 ms after stimulus onset, even when the sounds were task-irrelevant. We propose the existence of a mechanism for the detection of significant sounds that does not rely on the detection of acoustic deviation. From a comparison of the results from our active- and passive-listening conditions, this discriminative process based on individual memory schemata seems to be obligatory, whereas the impact of individual memory schemata on further stages of auditory processing may require top-down guidance.

Regional linguistic variations in Canadian French: Do they affect performance on speech perception in noise?

Many audiologists working with a Canadian French population use word recognition tests to measure speech perception abilities in noise. The TMB test (Test de Mots dans le Bruit) includes four lists of 35 words presented in babble noise. The test is intended to measure the pre-cognitive perceptual stage of auditory processing and does not require understanding of the phonetic differences between speech sounds at a cognitive level. Previous studies examining performance on auditory tests similar to the TMB showed differences between populations speaking the same language but with different accentuations, such as the English spoken in the United States versus the United Kingdom. Variations in performance were attributed to accentuation differences between the speaker and the listener. To the authors' knowledge, no study appears to have investigated the effect of regional linguistic variations of Canadian French on word recognition in noise. Normative data for the TMB are being collected in three regions of Canada: Moncton, Montreal and Ottawa. Participants are all native speakers of Canadian French, but there are important linguistic variations across the three regions. Knowledge of the effect of regional linguistic variations on the TMB performance will help refine interpretation of test results in the audiology clinics.

Bugs and bats: Neural analysis of behaviorally relevant sounds in crickets

Hearing in crickets is specialized to serve particular behavioral functions, namely intraspecific communication and predator avoidance. Male crickets produce species-specific acoustic signals (songs) that attract distant females, promote copulation, and contribute to agonistic interactions with rivals. Crickets also hear the echolocation calls of aerially hunting bats, which evoke avoidance responses. These clear behavioral functions of hearing, combined with the relative simplicity of the cricket's nervous system, make it possible to address questions about how behaviorally relevant sensory signals are analyzed at the level of single, uniquely identifiable nerve cells. Cricket songs and bat calls differ both in rhythm and in spectrum, and neurons throughout the auditory processing chain are specialized for processing these two sorts of signal. I will focus on specializations that are evident at early stages of auditory processing, i.e., primary sensory neurons and the first-order interneurons with which they interact.

Linguistic multi-feature paradigm as an eligible measure of central auditory processing and novelty detection in 2-year-old children

This study evaluated whether the linguistic multi-feature paradigm with five types of speech-sound changes and novel sounds is an eligible neurophysiologic measure of central auditory processing in toddlers. Participants were 18 typically developing 2-year-old children. Syllable stimuli elicited significant obligatory responses and syllable changes significant MMN (mismatch negativity) which suggests that toddlers can discriminate auditory features from alternating speech-sound stream. The MMNs were lateralized similarly as found earlier in adults. Furthermore, novel sounds elicited a significant novelty P3 response. Thus, the linguistic multi-feature paradigm with novel sounds is feasible for the concurrent investigation of the different stages of central auditory processing in 2-year-old children, ranging from pre-attentive encoding and discrimination of stimuli to attentional mechanisms in speech-like research compositions. As a conclusion, this time-efficient paradigm can be applied to investigating central auditory development and impairments in toddlers in whom developmental changes of speech-related cortical functions and language are rapid.

Inter‐subject synchronization of brain responses during natural music listening

Music is a cultural universal and a rich part of the human experience. However, little is known about common brain systems that support the processing and integration of extended, naturalistic 'real-world' music stimuli. We examined this question by presenting extended excerpts of symphonic music, and two pseudomusical stimuli in which the temporal and spectral structure of the Natural Music condition were disrupted, to non-musician participants undergoing functional brain imaging and analysing synchronized spatiotemporal activity patterns between listeners. We found that music synchronizes brain responses across listeners in bilateral auditory midbrain and thalamus, primary auditory and auditory association cortex, right-lateralized structures in frontal and parietal cortex, and motor planning regions of the brain. These effects were greater for natural music compared to the pseudo-musical control conditions. Remarkably, inter-subject synchronization in the inferior colliculus and medial geniculate nucleus was also greater for the natural music condition, indicating that synchronization at these early stages of auditory processing is not simply driven by spectro-temporal features of the stimulus. Increased synchronization during music listening was also evident in a right-hemisphere fronto-parietal attention network and bilateral cortical regions involved in motor planning. While these brain structures have previously been implicated in various aspects of musical processing, our results are the first to show that these regions track structural elements of a musical stimulus over extended time periods lasting minutes. Our results show that a hierarchical distributed network is synchronized between individuals during the processing of extended musical sequences, and provide new insight into the temporal integration of complex and biologically salient auditory sequences.

Early auditory sensory processing of voices is facilitated by visual mechanisms

How do we recognize people that are familiar to us? There is overwhelming evidence that our brains process voice and face in a combined fashion to optimally recognize both who is speaking and what is said. Surprisingly, this combined processing of voice and face seems to occur even if one stream of information is missing. For example, if subjects only hear someone who is familiar to them talking, without seeing their face, visual face-processing areas are active. One reason for this crossmodal activation might be that it is instrumental for early sensory processing of voices-a hypothesis that is contrary to current models of unisensory perception. Here, we test this hypothesis by harnessing a temporally highly resolved method, i.e., magnetoencephalography (MEG), to identify the temporal response profile of the fusiform face area in response to auditory-only voice recognition. Participants briefly learned a set of voices audio-visually, i.e., together with a talking face. After learning, we measured subjects' MEG signals in response to the auditory-only, now familiar, voices. The results revealed three key mechanisms that characterize the sensory processing of familiar speakers' voices: (i) activation in the face-sensitive fusiform gyrus at very early auditory processing stages, i.e., only 100ms after auditory onset, (ii) a temporal facilitation of auditory processing (M200), and (iii) a correlation of this temporal facilitation with recognition performance. These findings suggest that a neural representation of face information is evoked before the identity of the voice is even recognized and that the brain uses this visual representation to facilitate early sensory processing of auditory-only voices.

Compensatory changes in cortical resource allocation in adults with hearing loss

Hearing loss has been linked to many types of cognitive decline in adults, including an association between hearing loss severity and dementia. However, it remains unclear whether cortical re-organization associated with hearing loss occurs in early stages of hearing decline and in early stages of auditory processing. In this study, we examined compensatory plasticity in adults with mild-moderate hearing loss using obligatory, passively-elicited, cortical auditory evoked potentials (CAEP). High-density EEG elicited by speech stimuli was recorded in adults with hearing loss and age-matched normal hearing controls. Latency, amplitude and source localization of the P1, N1, P2 components of the CAEP were analyzed. Adults with mild-moderate hearing loss showed increases in latency and amplitude of the P2 CAEP relative to control subjects. Current density reconstructions revealed decreased activation in temporal cortex and increased activation in frontal cortical areas for hearing-impaired listeners relative to normal hearing listeners. Participants' behavioral performance on a clinical test of speech perception in noise was significantly correlated with the increases in P2 latency. Our results indicate that changes in cortical resource allocation are apparent in early stages of adult hearing loss, and that these passively-elicited cortical changes are related to behavioral speech perception outcome.

Relationship between auditory processing and affective prosody in schizophrenia

Patients with schizophrenia have well-established deficits in their ability to identify emotion from facial expression and tone of voice. In the visual modality, there is strong evidence that basic processing deficits contribute to impaired facial affect recognition in schizophrenia. However, few studies have examined the auditory modality for mechanisms underlying affective prosody identification. In this study, we explored links between different stages of auditory processing, using event-related potentials (ERPs), and affective prosody detection in schizophrenia. Thirty-six schizophrenia patients and 18 healthy control subjects received tasks of affective prosody, facial emotion identification, and tone matching, as well as two auditory oddball paradigms, one passive for mismatch negativity (MMN) and one active for P300. Patients had significantly reduced MMN and P300 amplitudes, impaired auditory and visual emotion recognition, and poorer tone matching performance, relative to healthy controls. Correlations between ERP and behavioral measures within the patient group revealed significant associations between affective prosody recognition and both MMN and P300 amplitudes. These relationships were modality specific, as MMN and P300 did not correlate with facial emotion recognition. The two ERP waves accounted for 49% of the variance in affective prosody in a regression analysis. Our results support previous suggestions of a relationship between basic auditory processing abnormalities and affective prosody dysfunction in schizophrenia, and indicate that both relatively automatic pre-attentive processes (MMN) and later attention-dependent processes (P300) are involved with accurate auditory emotion identification. These findings provide support for bottom-up (e.g., perceptually based) cognitive remediation approaches.

Electrophysiological evidence of temporal preparation driven by rhythms in audition

Reaction speed to respond to an auditory target stimulus is enhanced when it is presented at a moment matching the temporal structure of a preceding regular rhythm (Sanabria et al., 2011). However, the electrophysiological correlates of this behavioural enhancement remain unknown. In the present study, participants’ performed a simple auditory reaction time task in which a regular rhythm with either a fast (400ms interval between the tones making the rhythm) or a slow (900ms interval between the tones making the rhythm) was presented prior to the target. The target tone could be presented, with the same probability, 400ms or 900ms after the offset of the rhythmic sequence. The behavioural results showed that the fastest responses were obtained when the target appeared in synchrony with the preceding rhythm (e.g., the target was presented 900ms after the slow rhythm). This behavioural benefit was accompanied by amplitude modulations of the N1 potential and the P2 potential, both related to the processing of the auditory target. Crucially, these electrophysiological modulations were obtained in both the fast and the slow rhythm conditions. The current research demonstrates that rhythms with different paces can drive temporal preparation exogenously, affecting early and late stages of auditory neural processing.