Automatic and controlled processing of melodic contour and interval information measured by electrical brain activity

Listening strategy for auditory rhythms modulates neural correlates of expectancy and cognitive processing

A recently described auditory tempo perception paradigm revealed individual differences in perceived stimulus timing for identical stimulus sequences. The current study takes advantage of this paradigm by recording event-related potentials (ERPs) concurrent with task performance in order to reveal brain responses that reflect individual differences in timing strategy. No strategy-related differences were observed in sensory encoding of tones, as measured by the P1-N1-P2 complex. However, the contingent negative variation (CNV) leading up to the final tone of the sequence varied as a function of strategy, as did a parietal-maximum late positive component (P3b) that occurred following the final tone. These data suggest that temporal expectancy for and cognitive processing of the final tone of rhythmic sequences underlies differences in strategy during rhythm perception.

Sensory processing of linguistic pitch as reflected by the mismatch negativity

OBJECTIVE

To assess the extent to which acoustic and phonetic change-detection processes contribute to the mismatch negativity (MMN) to linguistic pitch contours.

DESIGN

MMN was elicited from Mandarin and English speakers using a passive oddball paradigm. Two oddball conditions were constructed. In one condition (T1/T2i), the Mandarin high-level tone (T1) was compared with a convex high-rising tone (inverted T2, henceforth referred to as T2i) that occurs as a contextual variant of T1 in running speech. In the other (T2/T2i), the concave high-rising tone (T2) was compared with T2i. Phonetically, T1/T2i represents a within-category contrast for native speakers, whereas T2/T2i represents a between-category contrast. The between-category pair (T2/T2i), however, is more similar acoustically than the within-category pair (T1/T2i). In an attention-demanding behavioral paradigm, the same speakers also performed an auditory discrimination task to determine the perceptual distinctiveness of the two tonal pairs.

RESULTS

Results revealed that the Chinese group, relative to the English, showed larger MMN responses and earlier peak latencies for both conditions, indicating experience-dependent enhancement in representing linguistically relevant pitch contours. At attentive stages of processing, however, the Chinese group was less accurate than the English in discriminating the within-category contrast (T1-T2i).

CONCLUSIONS

These findings demonstrate that experience-dependent neural effects at early preattentive stages of processing may be driven primarily by acoustic features of pitch contours that occur in natural speech. At attentive stages of processing, perception is strongly influenced by tonal categories and their relations to one another. The MMN is a useful index for examining long-term plasticity to linguistically relevant acoustic features.

Development of auditory phase-locked activity for music sounds

The auditory cortex undergoes functional and anatomical development that reflects specialization for learned sounds. In humans, auditory maturation is evident in transient auditory-evoked potentials (AEPs) elicited by speech or music. However, neural oscillations at specific frequencies are also known to play an important role in perceptual processing. We hypothesized that, if oscillatory activity in different frequency bands reflects different aspects of sound processing, the development of phase-locking to stimulus attributes at these frequencies may have different trajectories. We examined the development of phase-locking of oscillatory responses to music sounds and to pure tones matched to the fundamental frequency of the music sounds. Phase-locking for theta (4-8 Hz), alpha (8-14 Hz), lower-to-mid beta (14-25 Hz), and upper-beta and gamma (25-70 Hz) bands strengthened with age. Phase-locking in the upper-beta and gamma range matured later than in lower frequencies and was stronger for music sounds than for pure tones, likely reflecting the maturation of neural networks that code spectral complexity. Phase-locking for theta, alpha, and lower-to-mid beta was sensitive to temporal onset (rise time) sound characteristics. The data were also consistent with phase-locked oscillatory effects of acoustic (spectrotemporal) complexity and timbre familiarity. Future studies are called for to evaluate developmental trajectories for oscillatory activity, using stimuli selected to address hypotheses related to familiarity and spectral and temporal encoding suggested by the current findings.

Neural representation of transposed melody in infants at 6 months of age

We examined adults' and 6-month-old infants' event-related potentials in response to occasional changes (deviants) in a 4-note melody presented at different pitch levels from trial to trial. In both groups, responses to standard and deviant stimuli differed significantly; however, adults produced a typical mismatch negativity (MMN), whereas 6-month-old infants exhibited a slow positive wave. We conclude that 6-month-old infants, like adults, encode melodic information in terms of relative pitch distances, but that the underlying cortical activity differs significantly from that of adults.

A neurophysiological study into the foundations of tonal harmony

Our findings provide magnetoencephalographic evidence that the mismatch-negativity response to two-note chords (dyads) is modulated by a combination of abstract cognitive differences and lower-level differences in the auditory signal. Participants were presented with series of simple-ratio sinusoidal dyads (perfect fourths and perfect fifths) in which the difference between the standard and deviant dyad exhibited an interval change, a shift in pitch space, or both. In addition, the standard-deviant pair of dyads either shared one note or both notes were changed. Only the condition that featured both abstract changes (interval change and pitch-space shift) and two novel notes showed a significantly larger magnetoencephalographic mismatch-negativity response than the other conditions in the right hemisphere. Implications for music and language processing are discussed.

Structural decomposition of EEG signatures of melodic processing

In the current study we investigate the EEG response to listening and imagining melodies and explore the possibility of decomposing this response according to musical features, such as rhythm and pitch patterns. A structural model was created based on musical aspects and multiple regression was used to calculate profiles of the contribution of each aspect, in contrast to traditional ERP components. By decomposing the response, we aimed to uncover pronounced ERP contributions for aspects of the encoding of musical structure, assuming a simple additive combination of these. When using a model built up of metric levels and contour direction, 81% of the variance is explained for perceived, and 57% for imagined melodies. The maximum correlation between the parameters found for the same melodic aspect in perception vs. imagery was 0.88, indicating similar processing between tasks. The decomposition method is shown to be a novel analysis method of complex ERP patterns, which allows subcomponents to be investigated within a continuous context.

Neural basis of music imagery and the effect of musical expertise

Although the influence of long-term musical training on the processing of heard music has been the subject of many studies, the neural basis of music imagery and the effect of musical expertise remain insufficiently understood. By means of magnetoencephalography (MEG) we compared musicians and nonmusicians in a musical imagery task with familiar melodies. Subjects listened to the beginnings of the melodies, continued them in their imagination and then heard a tone which was either a correct or an incorrect further continuation of the melody. Only in musicians was the imagery of these melodies strong enough to elicit an early preattentive brain response to unexpected incorrect continuations of the imagined melodies; this response, the imagery mismatch negativity (iMMN), peaked approximately 175 ms after tone onset and was right-lateralized. In contrast to previous studies the iMMN was not based on a heard but on a purely imagined memory trace. Our results suggest that in trained musicians imagery and perception rely on similar neuronal correlates, and that the musicians' intense musical training has modified this network to achieve a superior ability for imagery and preattentive processing of music.

Development of infant mismatch responses to auditory pattern changes between 2 and 4 months old

In order to process speech and music, the auditory cortex must learn to process patterns of sounds. Our previous studies showed that with a stream consisting of a repeating (standard) sound, younger infants show an increase in the amplitude of a positive slow wave in response to occasional changes (deviants) in pitch or duration, whereas older infants show a faster negative response that resembles mismatch negativity (MMN) in adults (Trainor et al., 2001, 2003; He et al., 2007). MMN reflects an automatic change-detection process that does not require attention, conscious awareness or behavioural response for its elicitation (Picton et al., 2000; Näätänen et al., 2007). It is an important tool for understanding auditory perception because MMN reflects a change-detection mechanism, and not simply that repetition of a stimulus results in a refractory state of sensory neural circuits while occasional changes to a new sound activate new non-refractory neural circuits (Näätänen et al., 2005). For example, MMN is elicited by a change in the pattern of a repeating note sequence, even when no new notes are introduced that could activate new sensory circuits (Alain et al., 1994, 1999;Schröger et al., 1996). In the present study, we show that in response to a change in the pattern of two repeating tones, MMN in 4-month-olds remains robust whereas the 2-month-old response does not. This indicates that the MMN response to a change in pattern at 4 months reflects the activation of a change-detection mechanism similarly as in adults.

Music perception, pitch, and the auditory system

The perception of music depends on many culture-specific factors, but is also constrained by properties of the auditory system. This has been best characterized for those aspects of music that involve pitch. Pitch sequences are heard in terms of relative as well as absolute pitch. Pitch combinations give rise to emergent properties not present in the component notes. In this review we discuss the basic auditory mechanisms contributing to these and other perceptual effects in music.

Maturation of cortical mismatch responses to occasional pitch change in early infancy: effects of presentation rate and magnitude of change

Previous studies have reported two types of event-related potential (ERP) mismatch responses in infants to infrequent auditory changes: a broad discriminative positivity in younger infants and a negativity resembling adult mismatch negativity (MMN) in older infants. In the present study, we investigated whether the positive discriminative slow wave and the adult-like MMN are functionally distinct by examining how they are affected by presentation rate and magnitude of change. We measured ERPs from adults, 2-month-olds, and 4-month-olds to a repeating piano tone (standard) that occasionally changed in pitch (deviant). The pitch changes between standards and deviants were either small (1/12 octave) or large (1/2 octave) in magnitude, and the stimulus presentation rate was either slow (800 ms SOA) or fast (400 ms SOA). As the presentation rate increased, both adults and 4-month-olds showed an MMN response that decreased in latency, but was unaffected in amplitude. As the magnitude of the pitch change increased, MMN increased in amplitude. On the other hand, only a broad positive mismatch response was seen in 2-month-olds. As the presentation rate increased, 2-month-olds' responses to standard tones decreased in amplitude while their responses to deviant tones were unaffected. The magnitude of the pitch change did not affect 2-month-olds' responses. These results suggest that pitch is processed differently in auditory cortex by 2-month-olds and 4-month-olds, and that a cortical change-detection mechanism for pitch discrimination similar to that of adults emerges between 2 and 4 months of age.

fMRI evidence for a cortical hierarchy of pitch pattern processing

Pitch patterns, such as melodies, consist of two levels of structure: a global level, comprising the pattern of ups and downs, or contour; and a local level, comprising the precise intervals that make up this contour. An influential neuropsychological model suggests that these two levels of processing are hierarchically linked, with processing of the global structure occurring within the right hemisphere in advance of local processing within the left. However, the predictions of this model and its anatomical basis have not been tested in neurologically normal individuals. The present study used fMRI and required participants to listen to consecutive pitch sequences while performing a same/different one-back task. Sequences, when different, either preserved (local) or violated (global) the contour of the sequence preceding them. When the activations for the local and global conditions were contrasted directly, additional activation was seen for local processing in right planum temporale and posterior superior temporal sulcus (pSTS). The presence of additional activation for local over global processing supports the hierarchical view that the global structure of a pitch sequence acts as a “framework” on which the local detail is subsequently hung. However, the lateralisation of activation seen in the present study, with global processing occurring in left pSTS and local processing occurring bilaterally, differed from that predicted by the neuroanatomical model. A re-examination of the individual lesion data on which the neuroanatomical model is based revealed that the lesion data equally well support the laterality scheme suggested by our data. While the present study supports the hierarchical view of local and global processing, there is an evident need for further research, both in patients and neurologically normal individuals, before an understanding of the functional lateralisation of local and global processing can be considered established.

The mismatch negativity (MMN) in basic research of central auditory processing: a review

In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream.

Rhythm perception: Speeding up or slowing down affects different subcomponents of the ERP P3 complex

The aim of this study was to investigate, by measuring the event related potential (ERP) P3 complex, whether the perception of small accelerations differs from that of small decelerations. Participants had to decide whether the last beat of a short sequence was presented 'too early' or 'too late'. Target beats were accelerated or decelerated with 0%, 2%, 5%, or 10%. Individuals differed in their capability to detect small tempo changes. We found that good responders were able to identify all tempo changes whereas poor responders were only able to identify large (10%) tempo changes. In addition, we found that tempo changes affected two subcomponents of the ERP P3 in good performers. Accelerations increased a late-P3 amplitude whereas decelerations increased an early-P3 amplitude. These results imply the principle possibility to measure differential P3 effects within one task. This is important for acquiring more refined knowledge concerning different subcomponents of the ERP P3 complex and the cognitive processes by which they are elicited.

A mismatch negativity study of local-global auditory processing

We used mismatch negativity (MMN) to examine structural encoding of local and global auditory patterns in perceptual memory. Unlike previous MMN studies of local-global auditory perceptual organization that used interval-contour stimuli, here we presented hierarchical stimuli in which local pattern organization formed global patterns. Importantly, our stimuli allowed independent manipulation of the two structural levels. In separate blocks, participants were exposed to frequent local standard patterns and rare local deviant patterns, or to frequent global standard patterns and rare global deviant patterns. Within each deviant pattern, the variation from the standard pattern could occur at onset (early), towards the end of the pattern (late) or over both time windows (both). To isolate pattern indexing at one level, the other level continuously changed (e.g., in a global standard block, local elements varied trial-by-trial). MMN was found only for global deviant patterns, and only when deviation occurred late in the pattern. In a separate behavioral experiment, global deviants were detected more often than local ones, although initial similarity followed by a late deviation from the standard pattern was not required for explicit deviant detection (as with the MMN). This report demonstrates neural structural encoding for global information, when independently manipulated from local information. Furthermore, it extends previous MMN findings that have revealed indexing of complex abstract auditory information to the realm of hierarchical perceptual organization.

Practice strategies of musicians modulate neural processing and the learning of sound-patterns

Previous studies suggest that pre-attentive auditory processing of musicians differs depending on the strategies used in music practicing and performance. This study aimed at systematically revealing whether there are differences in auditory processing between musicians preferring and not-preferring aural strategies such as improvising, playing by ear, and rehearsing by listening to records. Participants were assigned to aural and non-aural groups according to how much they employ aural strategies, as determined by a questionnaire. The change-related mismatch negativity (MMN) component of event-related brain potentials (ERPs) was used to probe pre-attentive neural discrimination of simple sound features and melody-like patterns. Further, the musicians' behavioral accuracy in sound perception was tested with a discrimination task and the AMMA musicality test. The data indicate that practice strategies do not affect musicians' pre-attentive neural discrimination of changes in simple sound features but do modulate the speed of neural discrimination of interval and contour changes within melody-like patterns. Moreover, while the aural and non-aural groups did not differ in their initial neural accuracy for discriminating melody-like patterns, they differed after a focused training session. A correlation between behavioral and neural measures was also obtained. Taken together, these results suggest that auditory processing of musicians who prefer aural practice strategies differs in melodic contour and interval processing and perceptual learning, rather than in simple sound processing, in comparison to musicians preferring other practice strategies.

Musical scale properties are automatically processed in the human auditory cortex

While listening to music, we immediately detect 'wrong' tones that do not match our expectations based on the prior context. This study aimed to determine whether such expectations can occur preattentively, as indexed by event-related potentials (ERPs), and whether these are modulated by attentional processes. To this end, we recorded ERPs in nonmusicians while they were presented with unfamiliar melodies, containing either a pitch deviating from the equal-tempered chromatic scale (out-of-tune) or a pitch deviating from the diatonic scale (out-of-key). ERPs were recorded in a passive experiment in which subjects were distracted from the sounds and in an active experiment in which they were judging how incongruous each melody was. In both the experiments, pitch incongruities elicited an early frontal negativity that was not modulated by attentional focus. This early negativity, closely corresponding to the mismatch negativity (MMN) of the ERPs, was mainly originated in the auditory cortex and occurred in response to both pitch violations but with larger amplitude for the more salient out-of-tune pitch than the less salient out-of-key pitch. Attentional processes leading to the conscious access of musical scale information were indexed by the late parietal positivity (resembling the P600 of the ERPs) elicited in response to both incongruous pitches in the active experiment only. Our results indicate that the relational properties of the musical scale are quickly and automatically extracted by the auditory cortex even before the intervention of focused attention.

The biology and evolution of music: A comparative perspective

Studies of the biology of music (as of language) are highly interdisciplinary and demand the integration of diverse strands of evidence. In this paper, I present a comparative perspective on the biology and evolution of music, stressing the value of comparisons both with human language, and with those animal communication systems traditionally termed "song". A comparison of the "design features" of music with those of language reveals substantial overlap, along with some important differences. Most of these differences appear to stem from semantic, rather than structural, factors, suggesting a shared formal core of music and language. I next review various animal communication systems that appear related to human music, either by analogy (bird and whale "song") or potential homology (great ape bimanual drumming). A crucial comparative distinction is between learned, complex signals (like language, music and birdsong) and unlearned signals (like laughter, ape calls, or bird calls). While human vocalizations clearly build upon an acoustic and emotional foundation shared with other primates and mammals, vocal learning has evolved independently in our species since our divergence with chimpanzees. The convergent evolution of vocal learning in other species offers a powerful window into psychological and neural constraints influencing the evolution of complex signaling systems (including both song and speech), while ape drumming presents a fascinating potential homology with human instrumental music. I next discuss the archeological data relevant to music evolution, concluding on the basis of prehistoric bone flutes that instrumental music is at least 40,000 years old, and perhaps much older. I end with a brief review of adaptive functions proposed for music, concluding that no one selective force (e.g., sexual selection) is adequate to explaining all aspects of human music. I suggest that questions about the past function of music are unlikely to be answered definitively and are thus a poor choice as a research focus for biomusicology. In contrast, a comparative approach to music promises rich dividends for our future understanding of the biology and evolution of music.

Are we "experienced listeners"? A review of the musical capacities that do not depend on formal musical training

The present paper reviews a set of studies designed to investigate different aspects of the capacity for processing Western music. This includes perceiving the relationships between a theme and its variations, perceiving musical tensions and relaxations, generating musical expectancies, integrating local structures in large-scale structures, learning new compositional systems and responding to music in an emotional (affective) way. The main focus of these studies was to evaluate the influence of intensive musical training on these capacities. The overall set of data highlights that some musical capacities are acquired through exposure to music without the help of explicit training. These capacities reach such a degree of sophistication that they enable untrained listeners to respond to music as "musically experienced listeners" do.

Memory for melody: infants use a relative pitch code

Pitch perception is fundamental to melody in music and prosody in speech. Unlike many animals, the vast majority of human adults store melodic information primarily in terms of relative not absolute pitch, and readily recognize a melody whether rendered in a high or a low pitch range. We show that at 6 months infants are also primarily relative pitch processors. Infants familiarized with a melody for 7 days preferred, on the eighth day, to listen to a novel melody in comparison to the familiarized one, regardless of whether the melodies at test were presented at the same pitch as during familiarization or transposed up or down by a perfect fifth (7/12th of an octave) or a tritone (1/2 octave). On the other hand, infants showed no preference for a transposed over original-pitch version of the familiarized melody, indicating that either they did not remember the absolute pitch, or it was not as salient to them as the relative pitch.

Auditory attention to frequency and time: an analogy to visual local-global stimuli

Two priming experiments demonstrated exogenous attentional persistence to the fundamental auditory dimensions of frequency (Experiment 1) and time (Experiment 2). In a divided-attention task, participants responded to an independent dimension, the identification of three-tone sequence patterns, for both prime and probe stimuli. The stimuli were specifically designed to parallel the local-global hierarchical letter stimuli of [Navon D. (1977). Forest before trees: The precedence of global features in visual perception. Cognitive Psychology, 9, 353-383] and the task was designed to parallel subsequent work in visual attention using Navon stimuli [Robertson, L. C. (1996). Attentional persistence for features of hierarchical patterns. Journal of Experimental Psychology: General, 125, 227-249; Ward, L. M. (1982). Determinants of attention to local and global features of visual forms. Journal of Experimental Psychology: Human Perception and Performance, 8, 562-581]. The results are discussed in terms of previous work in auditory attention and previous approaches to auditory local-global processing.

Automatic Encoding of Polyphonic Melodies in Musicians and Nonmusicians

In music, multiple musical objects often overlap in time. Western polyphonic music contains multiple simultaneous melodic lines (referred to as “voices”) of equal importance. Previous electrophysiological studies have shown that pitch changes in a single melody are automatically encoded in memory traces, as indexed by mismatch negativity (MMN) and its magnetic counterpart (MMNm), and that this encoding process is enhanced by musical experience. In the present study, we examined whether two simultaneous melodies in polyphonic music are represented as separate entities in the auditory memory trace. Musicians and untrained controls were tested in both magnetoencephalogram and behavioral sessions. Polyphonic stimuli were created by combining two melodies (A and B), each consisting of the same five notes but in a different order. Melody A was in the high voice and Melody B in the low voice in one condition, and this was reversed in the other condition. On 50% of trials, a deviant final (5th) note was played either in the high or in the low voice, and it either went outside the key of the melody or remained within the key. These four deviations occurred with equal probability of 12.5% each. Clear MMNm was obtained for most changes in both groups, despite the 50% deviance level, with a larger amplitude in musicians than in controls. The response pattern was consistent across groups, with larger MMNm for deviants in the high voice than in the low voice, and larger MMNm for in-key than out-of-key changes, despite better behavioral performance for out-of-key changes. The results suggest that melodic information in each voice in polyphonic music is encoded in the sensory memory trace, that the higher voice is more salient than the lower, and that tonality may be processed primarily at cognitive stages subsequent to MMN generation.

Changing the tune: the structure of the input affects infants' use of absolute and relative pitch

Sequences of notes contain several different types of pitch cues, including both absolute and relative pitch information. What factors determine which of these cues are used when learning about tone sequences? Previous research suggests that infants tend to preferentially process absolute pitch patterns in continuous tone sequences, while other types of input elicit relative pitch use by infants. In order to ask whether the structure of the input influences infants' choice of pitch cues, we presented learners with continuous tone streams in which absolute pitch cues were rendered uninformative by transposing the tone sequences. Under these circumstances, both infants and adults successfully tracked relative pitches in a statistical learning task. Implications for the role played by the structure of the input in the learning process are considered.

Auditory organization of sound sequences by a temporal or numerical regularity—a mismatch negativity study comparing musicians and non-musicians

The human auditory system can encode regularities in the acoustic environment without the requirement of attention. We investigated whether the auditory system of musicians is more sensitive than that of non-musicians in encoding complex regularities. We presented tone sequences containing either a temporal or a numerical regularity. The sequence with the temporal regularity could be divided into segments of a constant duration while the segments contained a varying number of tones. The sequence with the numerical regularity, on the other hand, could be divided into segments containing a constant number of tones while the segments varied in duration. Auditory encoding of the regularity was determined by measuring whether an occasional segment lengthening, either in time or by number elicited the mismatch negativity (MMN). In both musicians and non-musicians, an MMN was elicited when the temporal regularity was violated. In contrast, only in musicians an MMN was elicited to violations of the numerical regularity. The results show that temporal processing is of general importance in audition since at an involuntary auditory processing stage a complex temporal regularity can be encoded irrespective of musical expertise. Furthermore, the auditory system of professional musicians can encode a numerical regularity without attention being required reflecting the functional importance of beat tracking in the perceptual organization of music.

Brain organization for music processing

Research on how the brain processes music is emerging as a rich and stimulating area of investigation of perception, memory, emotion, and performance. Results emanating from both lesion studies and neuroimaging techniques are reviewed and integrated for each of these musical functions. We focus our attention on the common core of musical abilities shared by musicians and nonmusicians alike. Hence, the effect of musical training on brain plasticity is examined in a separate section, after a review of the available data regarding music playing and reading skills that are typically cultivated by musicians. Finally, we address a currently debated issue regarding the putative existence of music-specific neural networks. Unfortunately, due to scarcity of research on the macrostructure of music organization and on cultural differences, the musical material under focus is at the level of the musical phrase, as typically used in Western popular music.

Musical structure modulates semantic priming in vocal music

It has been shown that harmonic structure may influence the processing of phonemes whatever the extent of participants' musical expertise [Bigand, E., Tillmann, B., Poulin, B., D'Adamo, D. A., & Madurell, F. (2001). The effect of harmonic context on phoneme monitoring in vocal music. Cognition, 81, B11-B20]. The present study goes a step further by investigating how musical harmony may potentially interfere with the processing of words in vocal music. Eight-chord sung sentences were presented, their last word being either semantically related (La girafe a un tres grand cou, The giraffe has a very long neck) or unrelated to the previous linguistic context (La girafe a un tres grand pied, The giraffe has a very long foot). The target word was sung on a chord that acted either as a referential tonic chord or as a congruent but less referential subdominant chord. Participants performed a lexical decision task on the target word. A significant interaction was observed between semantic and harmonic relatedness suggesting that music modulates semantic priming in vocal music. Following Jones' dynamic attention theory, we argue that music can modulate semantic priming in vocal music, by modifying the allocation of attentional resource necessary for linguistic computation.

Musical Training Enhances Automatic Encoding of Melodic Contour and Interval Structure

In music, melodic information is thought to be encoded in two forms, a contour code (up/down pattern of pitch changes) and an interval code (pitch distances between successive notes). A recent study recording the mismatch negativity (MMN) evoked by pitch contour and interval deviations in simple melodies demonstrated that people with no formal music education process both contour and interval information in the auditory cortex automatically. However, it is still unclear whether musical experience enhances both strategies of melodic encoding. We designed stimuli to examine contour and interval information separately. In the contour condition there were eight different standard melodies (presented on 80% of trials), each consisting of five notes all ascending in pitch, and the corresponding deviant melodies (20%) were altered to descending on their final note. The interval condition used one five-note standard melody transposed to eight keys from trial to trial, and on deviant trials the last note was raised by one whole tone without changing the pitch contour. There was also a control condition, in which a standard tone (990.7 Hz) and a deviant tone (1111.0 Hz) were presented. The magnetic counterpart of the MMN (MMNm) from musicians and nonmusicians was obtained as the difference between the dipole moment in response to the standard and deviant trials recorded by magnetoencephalography. Significantly larger MMNm was present in musicians in both contour and interval conditions than in nonmusicians, whereas MMNm in the control condition was similar for both groups. The interval MMNm was larger than the contour MMNm in musicians. No hemispheric difference was found in either group. The results suggest that musical training enhances the ability to automatically register abstract changes in the relative pitch structure of melodies.

Changes in auditory cortex and the development of mismatch negativity between 2 and 6 months of age

Evoked responses to stimulus deviance were compared in infants between 2 and 6 months of age. A deviant stimulus containing a short silent gap occasionally replaced a repeating standard stimulus matched in duration, intensity and approximate spectral content. At two months, the standard stimuli evoked only a positive slow wave, and its amplitude was increased in response to the deviant stimuli. By 6 months, the deviant stimuli evoked an increased negativity at approximately 200 ms, similar to the mismatch negativity (MMN) response in adults. The results are considered with respect to layer-specific cortical maturation during this period.

Rhythmic context influences the auditory evoked potentials of musicians and nonmusicians

In this study, we investigated how rhythms are processed in the brain by measuring both behaviourally obtained ratings and auditory evoked potentials (AEPs) from the EEG. We presented probe beats on seven positions within a test bar. Two bars of either a duple- or triple meter rhythm preceded probe beats. We hypothesised that sequential processing would lead to meter effects at the 1/3 and 1/2bar positions, whereas hierarchical processing would lead to context effects on the 1/3, 1/2 and 2/3bar positions. We found that metric contexts affected behavioural ratings. This effect was more pronounced for rhythmic experts. In addition, both the AEP P3a and P3b component could be identified. Though metric context affected the P3a amplitudes, group effects were less clear. We found that the AEP P3a component is sensitive to violation of temporal expectancies. In addition, behavioural data and P3a correlation coefficients (CCs) suggest that temporal patterns are processed sequentially in nonmusicians but are processed in a hierarchical way in rhythmic experts.

Grouping of Sequential Sounds—An Event-Related Potential Study Comparing Musicians and Nonmusicians

It is believed that auditory processes governing grouping and segmentation of sounds are automatic and represent universal aspects of music perception (e.g., they are independent of the listener's musical skill). The present study challenges this view by showing that musicians and nonmusicians differ in their ability to preattentively group consecutive sounds. We measured event-related potentials (ERPs) from professional musicians and nonmusicians who were presented with isochronous tone sequences that they ignored. Four consecutive tones in a sequence could be grouped according to either pitch similarity or good continuation of pitch. Occasionally, the tone-group length was violated by a deviant tone. The mismatch negativity (MMN) was elicited to the deviants in both subject groups when the sounds could be grouped based on pitch similarity. In contrast, MMN was only elicited in musicians when the sounds could be grouped according to good continuation of pitch. These results suggest that some forms of auditory grouping depend on musical skill and that not all aspects of auditory grouping are universal.

Translation from neurobiological data to music parameters

Composers have explored different ways to use biological information for the realization of music. Throughout the decades, biological findings have been repeatedly indicated as a source of inspiration or a reservoir of extramusical material for musical composition. More radical and fertile are attempts to produce music systematically using biological data in processes called data sonification or biofeedback techniques. Presented here is a novel strategy of translation where populations of neurobiological data are converted into relational structures from which sound objects are generated by flexible and homogeneous control of the sound parameters. All brain data originate from experiments performed with standard anatomical and physiological techniques, and results of studies based on these experimental materials have already been published. During the translation processes, the information for every sound parameter (such as pitch, duration, envelope, and dynamics) is never derived from fixed transcriptions of data properties. Rather, the space and/or the time interrelations of data populations are used to obtain indexes for sound construction. In this way, equivalent sets of information are exploited to model, or sculpt, the different parameters of sound objects. Three examples from the last decade's personal productions are given. The first refers to the microformal aspects of sound aggregation and is based on data from a microstimulation experiment in the motor cortex. The second describes the earliest translation process developed for live performance with conventional instruments and is based on experiments using a conventional tract tracing technique to compare selected spinal-projecting cell populations in two differently organized brains. The third outlines a recent music production for three pianos based on data from experiments using the multiple fluorescent tract-tracing technique to simultaneously label different populations of thalamocortical neurons. The approach here described can potentially contribute to a unitary view of the different sound parameters and of the micro- and macroformal aspects of the compositional process.

Effects of Musical Training on the Auditory Cortex in Children

Several studies of the effects of musical experience on sound representations in the auditory cortex are reviewed. Auditory evoked potentials are compared in response to pure tones, violin tones, and piano tones in adult musicians versus nonmusicians as well as in 4- to 5-year-old children who have either had or not had extensive musical experience. In addition, the effects of auditory frequency discrimination training in adult nonmusicians on auditory evoked potentials are examined. It was found that the P2-evoked response is larger in both adult and child musicians than in nonmusicians and that auditory training enhances this component in nonmusician adults. The results suggest that the P2 is particularly neuroplastic and that the effects of musical experience can be seen early in development. They also suggest that although the effects of musical training on cortical representations may be greater if training begins in childhood, the adult brain is also open to change. These results are discussed with respect to potential benefits of early musical training as well as potential benefits of musical experience in aging.

Musical minds

Music might be described as just a special form of noise, but evidence is accumulating to show that listening to it can lead to pronounced physiological and emotional responses. In a recent article, Trainor et al. have shown that specific aspects of musical structure are processed automatically in the human brain, raising the question of whether our response to music has specifically evolved or merely occurs as a side-effect of neural architecture.