Neural overlap in processing music and speech

Neural overlap in processing music and speech, as measured by the co-activation of brain regions in neuroimaging studies, may suggest that parts of the neural circuitries established for language may have been recycled during evolution for musicality, or vice versa that musicality served as a springboard for language emergence. Such a perspective has important implications for several topics of general interest besides evolutionary origins. For instance, neural overlap is an important premise for the possibility of music training to influence language acquisition and literacy. However, neural overlap in processing music and speech does not entail sharing neural circuitries. Neural separability between music and speech may occur in overlapping brain regions. In this paper, we review the evidence and outline the issues faced in interpreting such neural data, and argue that converging evidence from several methodologies is needed before neural overlap is taken as evidence of sharing.     

Respiratory impedance to ambient pressure changes at low frequencies

Respiratory impedance may be studied by measuring airway flow (Vaw) when pressure is varied at the mouth (input impedance) or around the chest (transfer impedance). A third possibility, which had not been investigated so far, is to apply pressure variations simultaneously at the two places, that is to vary ambient pressure (Pam). This provides respiratory impedance to ambient pressure changes (Zapc = Vaw/Pam). In that situation airway impedance (Zaw) and tissue impedance (Zt) are mechanically in parallel, and both are in series with alveolar gas impedance (Zg): Zapc = Zaw + Zg + Zaw.Zg/Zt. We assessed the frequency dependence of Zapc from 0.05 to 2 Hz in nine normal subjects submitted to sinusoidal Pam changes of 2-4 kPa peak to peak. The real part of Zapc (Rapc) was of 6.2 kPa.1(-1).s at 0.05 Hz and decreased to 1.9 kPa.1(-1).s at 2 Hz. Similarly the effective compliance (Capc), computed from the imaginary part of Zapc, decreased from 0.045 1.kPa-1 at 0.05 Hz to 0.027 1.kPa-1 at 2 Hz. Breathing against an added resistance of 0.46 kPa.1(-1).s exaggerated the negative frequency dependence of both Rapc and Capc. When values of airway resistance and inertance derived from transfer impedance data were introduced, Zapc was used to compute effective tissue resistance (Rt) and compliance (Ct). Rt was found to decrease from 0.32 to 0.15 kPa.1(-1).s and Ct from 1.11 to 0.64 1.kPa-1 between 0.25 and 2 Hz. Ct was slightly lower with the added resistance. These results are in good agreement with the data obtained by other approaches.     

Forced oscillatory impedance of the respiratory system at low frequencies

Respiratory mechanical impedances were determined during voluntary apnea in five healthy subjects, by means of 0.25- to 5-Hz pseudo/random oscillations applied at the mouth. The total respiratory impedance was partitioned into pulmonary (ZL) and chest wall components with the esophageal balloon technique; corrections were made for the upper airway shunt impedance and the compressibility of alveolar gas. Neglect of these shunt effects did not qualitatively alter the frequency dependence of impedances but led to underestimations in impedance, especially in the chest wall resistance (Rw), which decreased by 20-30% at higher frequencies. The total resistance (Rrs) was markedly frequency dependent, falling from 0.47 +/- 0.06 (SD) at 0.25 Hz to 0.17 +/- 0.01 at 1 Hz and 0.15 +/- 0.01 kPa X l-1 X s at 5 Hz. The changes in Rrs were caused by the frequency dependence of Rw almost exclusively between 0.25 and 2 Hz and in most part between 2 and 5 Hz. The effective total respiratory (Crs,e) and pulmonary compliance were computed with corrections for pulmonary inertance derived from three- and five-parameter model fittings of ZL. Crs,e decreased from the static value (1.03 +/- 0.18 l X kPa-1) to a level of approximately 0.35 l X kPa-1 at 2-3 Hz; this change was primarily caused by the frequency-dependent behavior of chest wall compliance.     

Viscoelastic properties of gerbil tympanic membrane at very low frequencies

The tympanic membrane transfers sound waves in the ear canal to mechanical vibrations in the middle ear and cochlea. Good estimates of the mechanical properties of the tympanic membrane are important to obtain realistic models. Up till now, only limited resources about tympanic membrane viscoelastic properties are available in the literature. This study aimed to quantify the viscoelastic properties of gerbil tympanic membrane. Step indentations were applied with a custom indenter on four fresh, intact tympanic membranes and the resulting force relaxation was measured. The reduced relaxation functions were then fitted with two viscoelastic model representations: a 5-parameter Maxwell model and a model with a continuous relaxation spectrum. The average relaxation function is described by an initial rapid decrease of 6.5% with characteristic time 0.77 s, followed by a long term decrease with characteristic time 46 s that gradually tends stable till a total relaxation of 15%. The relaxation curves in the time domain were transformed to complex moduli in the frequency domain. It was found that these transformations yield information on strain-rate dependence only from quasi-static to the very lowest acoustic frequencies. Finally, relaxation and hysteresis were simulated in a finite element model with viscoelastic material properties.     

Measurement of pleural pressure at low and high frequencies in normal rabbits

In eight tracheotomized adult rabbits placed in the supine position, we employed a catheter-tip piezoresistive pressure transducer to measure esophageal pressure (Pes) and assessed the validity of taking the changes in Pes to be the changes in pleural pressure (Ppl). We applied an occlusion test in which the tracheal cannula was occluded during either spontaneous inspiratory efforts or body surface oscillations ranging from 3 to 50 Hz. The relationship between Pes and airway opening pressure (Pao) was recorded. In all instances, the changes in Pes and Pao were virtually identical in both amplitude and phase. We conclude that, as evaluated by the occlusion test, a catheter-tip pressure transducer placed in the esophagus of rabbits can give adequate estimation of local pleural changes up to at least 50 Hz.     

ITS1 metabarcoding highlights low specificity of lichen mycobiomes at a local scale

As self‐supporting and long‐living symbiotic structures, lichens provide a habitat for many other organisms beside the traditionally considered lichen symbionts—the myco‐ and the photobionts. The lichen‐inhabiting fungi either develop diagnostic phenotypes or occur asymptomatically. Because the degree of specificity towards the lichen host is poorly known, we studied the diversity of these fungi among neighbouring lichens on rocks in an alpine habitat. Using a sequencing metabarcoding approach, we show that lichen mycobiomes clearly reflect the overlap of multiple ecological sets of taxa, which differ in their trophic association with lichen thalli. The lack of specificity to the lichen mycobiome is further supported by the lack of community structure observed using clustering and ordination methods. The communities encountered across samples largely result from the subsampling of a shared species pool, in which we identify three major ecological components: (i) a generalist environmental pool, (ii) a lichenicolous/endolichenic pool and (iii) a pool of transient species. These taxa majorly belong to the fungal classes Dothideomycetes, Eurotiomycetes and Tremellomycetes with close relatives in adjacent ecological niches. We found no significant evidence that the phenotypically recognized lichenicolous fungi influence the occurrence of the other asymptomatic fungi in the host thalli. We claim that lichens work as suboptimal habitats or as a complex spore and mycelium bank, which modulate and allow the regeneration of local fungal communities. By performing an approach that minimizes ambiguities in the taxonomic assignments of fungi, we present how lichen mycobiomes are also suitable targets for improving bioinformatic analyses of fungal metabarcoding.     

Characteristics of transverse electric and magnetic field transmission cells at extremely low frequencies

Transverse electric and magnetic field (TEM) cells are often designed to subject samples to electromagnetic radiation of intrinsic impedance (E/H) that is the same as in free space, 377 omega. Earlier work has shown this value to be correct for the RF region above about 2 kHz. In this study, measurements of magnetic fields in the extremely low frequency regions and at DC indicate the E/H ratio to be around 300 omega for frequencies less than 2 kHz in cells of a particular design. This lower value indicates that care should be taken in estimating AC magnetic field intensities from electric field measurements in TEM cells at frequencies below 2 kHz.     

Satellite tracking of manta rays highlights challenges to their conservation

We describe the real-time movements of the last of the marine mega-vertebrate taxa to be satellite tracked - the giant manta ray (or devil fish, Manta birostris), the world's largest ray at over 6 m disc width. Almost nothing is known about manta ray movements and their environmental preferences, making them one of the least understood of the marine mega-vertebrates. Red listed by the International Union for the Conservation of Nature as 'Vulnerable' to extinction, manta rays are known to be subject to direct and incidental capture and some populations are declining. Satellite-tracked manta rays associated with seasonal upwelling events and thermal fronts off the Yucatan peninsula, Mexico, and made short-range shuttling movements, foraging along and between them. The majority of locations were received from waters shallower than 50 m deep, representing thermally dynamic and productive waters. Manta rays remained in the Mexican Exclusive Economic Zone for the duration of tracking but only 12% of tracking locations were received from within Marine Protected Areas (MPAs). Our results on the spatio-temporal distribution of these enigmatic rays highlight opportunities and challenges to management efforts.     

Co-variation of tonality in the music and speech of different cultures

Whereas the use of discrete pitch intervals is characteristic of most musical traditions, the size of the intervals and the way in which they are used is culturally specific. Here we examine the hypothesis that these differences arise because of a link between the tonal characteristics of a culture's music and its speech. We tested this idea by comparing pitch intervals in the traditional music of three tone language cultures (Chinese, Thai and Vietnamese) and three non-tone language cultures (American, French and German) with pitch intervals between voiced speech segments. Changes in pitch direction occur more frequently and pitch intervals are larger in the music of tone compared to non-tone language cultures. More frequent changes in pitch direction and larger pitch intervals are also apparent in the speech of tone compared to non-tone language cultures. These observations suggest that the different tonal preferences apparent in music across cultures are closely related to the differences in the tonal characteristics of voiced speech.     

Transfer function of sound transmission in subglottal human respiratory system at low frequencies

The amplitude of sound transmission from the mouth to a site overlying the extrathoracic trachea and two sites on the posterior chest wall was measured in eight healthy adult male subjects at resting lung volume over the 100- to 600-Hz frequency range. The ratios of the estimated magnitude spectra of transmission of each of the chest wall sites to the tracheal site were determined, with the resulting spectra representing effective transfer functions of transmission in the subglottal system. For the group, the transfer functions exhibited a single peak, which occurred at 143 +/- 13 Hz (mean +/- SD) with a quality factor (Q) of 2.0 +/- 0.2 for the upper chest wall site and at 129 +/- 6 Hz with a Q of 2.2 +/- 0.4 for the lower site. The trend of decreasing spectral energy with increasing frequency was indicated by roll-offs of -10 +/- 4 and -17 +/- 5 dB/octave from 300 to 600 Hz at the two sites, respectively. The fundamental radial mode of a model thoracic cavity, which is a large rigid cylinder filled with lossless lung tissue, provides a good estimate of the observed low-frequency resonance. This agreement suggests that thoracic cavity resonances may have particularly important effects on sound transmission at frequencies below approximately 250 Hz, where the magnitude of parenchymal attenuation appears to be small.     

Non-bias-limited tracking of spherical particles, enabling nanometer resolution at low magnification

We present a three-dimensional tracking routine for nondiffraction-limited particles, which significantly reduces pixel bias. Our technique allows for increased resolution compared to that of previous methods, especially at low magnification or at high signal/noise ratio. This enables tracking with nanometer accuracy in a wide field of view and tracking of many particles. To reduce bias induced by pixelation, the tracking algorithm uses interpolation of the image on a circular grid to determine the x-, y-, and z-positions. We evaluate the proposed algorithm by tracking simulated images and compare it to well-known center-of-mass and cross-correlation methods. The final resolution of the described method improves up to an order of magnitude in three dimensions compared to conventional tracking methods. We show that errors in x,y-tracking can seriously affect z-tracking if interpolation is not used. We validate our results with experimental data obtained for conditions matching those used in the simulations. Finally, we show that the increased performance of the proposed algorithm uniquely enables it to extract accurate data for the persistence length and end-to-end distance of 107 DNA tethers in a single experiment.     

Coding interaural time differences at low best frequencies in the barn owl.

In birds and mammals, precisely timed spikes encode the timing of acoustic stimuli, and interaural acoustic disparities propagate to binaural processing centers. The Jeffress model proposes that these projections act as delay lines to innervate an array of coincidence detectors, every element of which has a different relative delay between its ipsilateral and contralateral excitatory inputs. Thus, interaural time difference (ITD) is encoded into the position of the coincidence detector whose delay lines best cancel out the acoustic ITD. Neurons of the avian nucleus laminaris and mammalian MSO phase-lock to both monaural and binaural stimuli but respond maximally when phase-locked spikes from each side arrive simultaneously, i.e. when the difference in the conduction delays compensates for the ITD. McAlpine et al. [Nat. Neurosci. 4 (2001) 396] identified an apparent difference between avian and mammalian ITD coding. In the barn owl, the maximum firing rate appears to encode ITD. This may not be the case for the guinea pig, where the steepest region of the function relating discharge rate to interaural time delay (ITD) is close to midline for all neurons, irrespective of best frequency (BF). These data suggest that low BF ITD sensitivity in the guinea pig is mediated by detection of a change in slope of the ITD function, and not by maximum rate. We review coding of low best frequency ITDs in barn owls and mammals and discuss whether there may be differences in the code used to signal ITD in mammals and birds.     

Coupling of sympathetic nerve traffic and BP at very low frequencies is mediated by large-amplitude events

This study explores the functional association between renal sympathetic nerve traffic (NT) and arterial blood pressure (BP) in the very-low-frequency range (i.e., <0.1 Hz). NT and BP (n = 6) or BP alone (n = 17) was recorded in unanesthetized rats (n = 6). Data were collected for 2-5 h, and wavelet transforms were calculated from data epochs of up to 1 h. From these transforms, we obtained probability distributions for fluctuation amplitudes over a range of time scales. We also computed the cross-wavelet power spectrum between NT and BP to detect the occurrence in time of large-amplitude transient events that may be important in the autonomic regulation of BP. Finally, we computed a time sequence of cross correlations between NT and BP to follow the relationship between NT and BP in time. We found that NT and BP follow comparable self-similar scaling relationships (i.e., NT and BP fluctuations exhibit a certain type of power law behavior). Scaling of this nature 1) points to underlying dynamics over a wide range of scales and 2) is related to large-amplitude events that contribute to the very-low-frequency variability of NT and BP. There is a strong correlation between NT and BP during many of these transient events. These strong correlations and the uniformity in scaling imply a functional connection between these two signals at frequencies where we previously found no connection using spectral coherence.     

Situational influences on rhythmicity in speech,music, and their interaction

Brain processes underlying the production and perception of rhythm indicate considerable flexibility in how physical signals are interpreted. This paper explores how that flexibility might play out in rhythmicity in speech and music. There is much in common across the two domains, but there are also significant differences. Interpretations are explored that reconcile some of the differences, particularly with respect to how functional properties modify the rhythmicity of speech, within limits imposed by its structural constraints. Functional and structural differences mean that music is typically more rhythmic than speech, and that speech will be more rhythmic when the emotions are more strongly engaged, or intended to be engaged. The influence of rhythmicity on attention is acknowledged, and it is suggested that local increases in rhythmicity occur at times when attention is required to coordinate joint action, whether in talking or music-making. Evidence is presented which suggests that while these short phases of heightened rhythmical behaviour are crucial to the success of transitions in communicative interaction, their modality is immaterial: they all function to enhance precise temporal prediction and hence tightly coordinated joint action.     

Hypothalamic autostimulation in rats at low frequencies of stimulation on the basis of locomotion]

A study was made of the hypothalamic autostimulation of rats with the impulse stimulation frequency of from 30 to 7 cycles/sec. The animals' brain was stimulated in Skinner's chamber and on the basis of locomotion. The duration of a series of impulses established by the animal on the basis of locomotion grew with reduction of the frequency of stimulation impulses. The pauses between the series of impulses and the duration of the series were also prolonged with a voltage reduction. With the help of stimulation frequency of 7 cycles it was possible to choose such a current that the sum of the total duration of pauses lay within 0 divided by 10% of the total experimental time. The duration of individual pauses was less than 0.5 sec.     

Zipf's law in short-time timbral codings of speech, music, and environmental sound signals

Timbre is a key perceptual feature that allows discrimination between different sounds. Timbral sensations are highly dependent on the temporal evolution of the power spectrum of an audio signal. In order to quantitatively characterize such sensations, the shape of the power spectrum has to be encoded in a way that preserves certain physical and perceptual properties. Therefore, it is common practice to encode short-time power spectra using psychoacoustical frequency scales. In this paper, we study and characterize the statistical properties of such encodings, here called timbral code-words. In particular, we report on rank-frequency distributions of timbral code-words extracted from 740 hours of audio coming from disparate sources such as speech, music, and environmental sounds. Analogously to text corpora, we find a heavy-tailed Zipfian distribution with exponent close to one. Importantly, this distribution is found independently of different encoding decisions and regardless of the audio source. Further analysis on the intrinsic characteristics of most and least frequent code-words reveals that the most frequent code-words tend to have a more homogeneous structure. We also find that speech and music databases have specific, distinctive code-words while, in the case of the environmental sounds, this database-specific code-words are not present. Finally, we find that a Yule-Simon process with memory provides a reasonable quantitative approximation for our data, suggesting the existence of a common simple generative mechanism for all considered sound sources.     

Hearing feelings: affective categorization of music and speech in alexithymia, an ERP study

Background

Alexithymia, a condition characterized by deficits in interpreting and regulating feelings, is a risk factor for a variety of psychiatric conditions. Little is known about how alexithymia influences the processing of emotions in music and speech. Appreciation of such emotional qualities in auditory material is fundamental to human experience and has profound consequences for functioning in daily life. We investigated the neural signature of such emotional processing in alexithymia by means of event-related potentials.

Methodology

Affective music and speech prosody were presented as targets following affectively congruent or incongruent visual word primes in two conditions. In two further conditions, affective music and speech prosody served as primes and visually presented words with affective connotations were presented as targets. Thirty-two participants (16 male) judged the affective valence of the targets. We tested the influence of alexithymia on cross-modal affective priming and on N400 amplitudes, indicative of individual sensitivity to an affective mismatch between words, prosody, and music. Our results indicate that the affective priming effect for prosody targets tended to be reduced with increasing scores on alexithymia, while no behavioral differences were observed for music and word targets. At the electrophysiological level, alexithymia was associated with significantly smaller N400 amplitudes in response to affectively incongruent music and speech targets, but not to incongruent word targets.

Conclusions

Our results suggest a reduced sensitivity for the emotional qualities of speech and music in alexithymia during affective categorization. This deficit becomes evident primarily in situations in which a verbalization of emotional information is required.     

Residue frequencies and pairing preferences at protein-protein interfaces

We used a nonredundant set of 621 protein-protein interfaces of known high-resolution structure to derive residue composition and residue-residue contact preferences. The residue composition at the interfaces, in entire proteins and in whole genomes correlates well, indicating the statistical strength of the data set. Differences between amino acid distributions were observed for interfaces with buried surface area of less than 1,000 A(2) versus interfaces with area of more than 5,000 A(2). Hydrophobic residues were abundant in large interfaces while polar residues were more abundant in small interfaces. The largest residue-residue preferences at the interface were recorded for interactions between pairs of large hydrophobic residues, such as Trp and Leu, and the smallest preferences for pairs of small residues, such as Gly and Ala. On average, contacts between pairs of hydrophobic and polar residues were unfavorable, and the charged residues tended to pair subject to charge complementarity, in agreement with previous reports. A bootstrap procedure, lacking from previous studies, was used for error estimation. It showed that the statistical errors in the set of pairing preferences are generally small; the average standard error is approximately 0.2, i.e., about 8% of the average value of the pairwise index (2.9). However, for a few pairs (e.g., Ser-Ser and Glu-Asp) the standard error is larger in magnitude than the pairing index, which makes it impossible to tell whether contact formation is favorable or unfavorable. The results are interpreted using physicochemical factors and their implications for the energetics of complex formation and for protein docking are discussed. Proteins 2001;43:89-102.     

Resonances of biological cells at audible frequencies

Two theories are discussed to account for the observed resonances of biological cells at sonic frequencies. One theory assumes the cell wall to be a stretched balloon surrounded by, and filled with, an incompressible fluid. The other treats the cell wall as a rigid shell. Both lead to reasonable physical constants for the cell wall. The initial phases of this work were supported by a grant from the Wisconsin Alumni Research Foundation to Professor H. B. Wahlin and were included in the author's theses submitted to the Graduate School of the University of Wisconsin in partial fulfillment of the degree of Doctor of Philosophy, August, 1949. The work is being supported at present by a grant to the Johnson Foundation from the Raytheon Manufacturing Company.