Pitch Perception Research Articles

Neural oscillation to Mandarin lexical tone processing in bilingual children: A developmental study

Tonal language experience is associated with structural and functional characteristics in the brain that underlie facilitated pitch perception. However, it is less understood what the developmental trajectory is for lexical tone processing at the cortical level, especially in bilingual children. In the present research, we investigated these developmental changes in terms of neuronal oscillations in response to Mandarin lexical tone contrasts. We measured lexical tone processing in bilingual English-Mandarin learning children and bilingual English-Mandarin young adults. Event-related brain potentials (ERPs) were recorded in an oddball paradigm with two tonal contrasts: one with a small acoustical difference, and one with a larger acoustical difference. We then analyzed the phase locking and amplitude modulation of ongoing oscillations in theta (4–8 Hz), alpha (8–14 Hz), and beta (14–30 Hz) bands to two types of lexical tone changes. Preliminary results suggest developmental changes were associated with strengthened phase locking of neural oscillations to both small and large acoustical contrasts, while stronger phase locking and higher power was observed in the larger acoustical contrast. Beyond this, the theta, alpha, and beta bands demonstrated different sensitivities to developmental changes. Such findings further our understanding of bilingual lexical tone development at the cortical level.

Multimodal training on L2 Japanese pitch accent: learning outcomes, neural correlates and subjective assessments

Abstract Japanese pitch accent is phonemic, making it crucial for second-language learners to acquire. Building on theories of multimodal learning, the present study explored how auditory, visual and gestural training of Japanese pitch accent affected behavioral, neural and meta-cognitive aspects of pitch perception across two experiments. Experiment 1 used a between-subjects pre/posttest design to train native English speakers to perceive Japanese pitch accents in one of the following three conditions: (1) baseline (audio + flat notation), (2) pitch height notation (audio + notation mimicking pitch height) and (3) pitch height notation + a left-hand gesture (L-gesture) (to engage the contralateral right hemisphere specialized for suprasegmental pitch processing). Our results indicated that (2) pitch height notation training was most robust in its benefits, as participants in this condition improved on trained and novel words alike. Experiment 2 used a within-subjects design to extend Experiment 1 in three ways: adding a right-hand gesture (R-gesture) condition (to engage more segmental language areas in the left hemisphere), introducing a neural correlate of cognitive load (measured by EEG alpha and theta power) and performing a metacognitive subjective assessment of learning (e.g., ‘Which training did you find the most helpful?’). The results showed that although there were no differences among our four training conditions on learning outcomes or EEG power, participants made the most positive subjective evaluations about pitch height notation and R-gesture training. Together, the results suggest that there may be a ‘just right’ amount of multimodal instruction to boost learning and increase engagement during foreign language pitch instruction.

Altered vocal communication in adult vasopressin-deficient Brattleboro rats

The neuropeptide, arginine vasopressin (AVP), has been implicated in social communication across a diverse array of species. Many rodents communicate basic behavioral states with negative versus positive valence through high-pitched vocalizations above the human hearing range (ultrasonic vocalizations; USVs). Previous studies have found that Brattleboro (Bratt) rats, which have a mutation in the Avp gene, exhibit deficits in their USVs from the early postnatal period through adolescence, but the magnitude of this effect appears to decrease from the juvenile to adolescent phase. The present study tested whether Bratt rats continue to exhibit USV deficits in adulthood. USVs of adult male and female Bratt and wild type (WT) rats were recorded in two contexts: a novel environment (empty arena) and a social context (arena filled with bedding soiled by same-sex conspecifics). The number, frequency, and duration of 50 kHz USVs were quantified by DeepSqueak after validation with manual scoring. Twenty-two kHz measures were quantified by manual scoring because DeepSqueak failed to accurately detect USVs in this frequency range. Adult Bratt rats did not exhibit deficits in the number of 50 kHz USVs: male Bratt rats emitted similar 50 kHz USVs as male WT rats, whereas female Bratt rats emitted more USVs than female WT rats. USV frequency and duration were altered in adult Bratt rats, but in a context-dependent manner. Twenty-two kHz USVs were less affected by the Bratt mutation. The present study demonstrates how chronic AVP deficiency impacts social communication across the lifespan. The present findings reveal a complex role for AVP in vocal communication, whereby disruption to the Avp gene leads to sex-, context-, and developmental phase-specific effects on the quantity and spectrotemporal characteristics of rat USVs.

Native language background affects the perception of duration and pitch

Estonian is a quantity language with both a primary duration cue and a secondary pitch cue, whereas Chinese is a tonal language with a dominant pitch use. Using a mismatch negativity experiment and a behavioral discrimination experiment, we investigated how native language background affects the perception of duration only, pitch only, and duration plus pitch information. Chinese participants perceived duration in Estonian as meaningless acoustic information due to a lack of phonological use of duration in their native language; however, they demonstrated a better pitch discrimination ability than Estonian participants. On the other hand, Estonian participants outperformed Chinese participants in perceiving the non-speech pure tones that resembled the Estonian quantity (i.e., containing both duration and pitch information). Our results indicate that native language background affects the perception of duration and pitch and that such an effect is not specific to processing speech sounds.

Musician Advantage for Segregation of Competing Speech in Native Tonal Language Speakers

The aim of this study was to replicate previous English-language musician advantage studies in Mandarin-speaking musicians and nonmusicians. Segregation of competing speech, melodic pitch perception, and spectro-temporal pattern perception were measured in normal-hearing native Mandarin-speaking musicians and nonmusicians. Speech recognition thresholds were measured in the presence of two-talker masker speech. The masker sex was either the same as or different from the target; target and masker speech were either co-located or spatially separated. Melodic pitch perception was tested using a melodic contour identification task. Spectro-temporal resolution was measured using a modified spectral ripple detection task. We hypothesized that, given musician advantages in pitch perception, musician effects would be larger when the target and masker sex was the same than when different. For all tests, performance was significantly better for musicians than for nonmusicians. Contrary to our expectation, larger musician effects were observed for segregation of competing speech when the target and masker sex was different. The results show that musician effects observed for non-tonal language speakers extend to tonal language speakers. The data also suggest that musician effects may depend on the difficulty of the listening task and may be reduced when listening tasks are too easy or too difficult.

Temporal fine structure sensitivity measured with pulse-spreading harmonic complexes.

Two experiments investigated sensitivity to temporal fine structure (TFS) in a group of normal hearing participants. The stimuli were bandpass filtered pulse-spreading harmonic complexes (PSHCs) with a regular envelope repetition rate and a phase adjusted so that the TFS peaks were progressively shifted across envelope periods. For up-PSHCs, the TFS peaks were advanced, yielding a rising pitch percept, while for down-PSHCs, the peaks were delayed, yielding a falling pitch percept. Experiment 1 showed that in a fixed frequency region, there was a range of rates for which the direction of the pitch change could be identified. Cochlear model simulations suggested that participants may use either place-of-excitation and/or temporal cues to perform this task. Experiment 2 showed that there was an envelope rate below which down-PSHCs and up-PSHCs could not be discriminated. This lower envelope rate limit of TFS sensitivity significantly increased with increases in frequency region and was similar to the lower rate limit of melodic pitch. The results in high frequency regions suggest that TFS cues are available up to 10 kHz when the rank of the lowest component present in the passband is 18, and all harmonics are presumably unresolved.

Effects of selective stimulation of apical electrodes on temporal pitch perception by cochlear implant recipients.

This study investigated whether selective apical stimulation improves temporal pitch perception in eight MED-EL cochlear implant recipients and whether any such improvement relates to auditory-nerve survival. Three stimulation conditions differing in the place and width of excitation were evaluated: single-electrode stimulation of (i) the most apical, (ii) a mid-array electrode, and (iii) multi-electrode stimulation of the four most apical electrodes. Stimulation-current-induced non-stimulating electrode voltages were recorded to identify extracochlear electrodes and gauge insertion depth. The pitches of the four most apical electrodes were compared using place-pitch ranking. Rate-pitch ranking was assessed between 80 and 981 pulses per second for the three stimulation conditions, to estimate the "upper limit" of temporal pitch. Single-electrode apical stimulation did not increase the upper limit relative to other conditions. The polarity effect (PE), defined as the difference between thresholds obtained for triphasic pulse trains with their central high-amplitude phase either anodic or cathodic, was obtained to evaluate peripheral neural health. The PE did not differ between apical and mid-array stimulation or correlate with the upper limit. In conclusion, we found no improvement of temporal pitch perception with single-electrode apical stimulation, and discuss possible explanations for this observation.

Perception of Pitch and Duration Pattern of Vowel /a/: A Comparison across Age and Gender in 5 to 9 Years Old Children

Abstract Objectives The present study aimed to develop pitch pattern test (PPT) and duration pattern test (DPT) using vowel and investigate the temporal ordering skills among typically developing children aged 5 to 9 years across genders. The study compared the performance of children on these tests across different age groups and gender. The study also investigated the relationship between performance on the DPT and PPT tasks using the vowel /a/. Materials and Methods Two verbal stimuli tests, DPT and PPT, were developed. For DPT, the vowel /a/ was used at 246 Hz and had two different durations of 500 and 250 ms for long and short stimuli, respectively, with a 300-ms interstimulus interval. For PPT, the vowel /a/ was used at 220 Hz for “low” stimuli and 261 Hz for “high” stimuli, both lasting 500 ms, with a 300-ms interstimulus duration and a 6-second intersequence duration.A cross-sectional study design was utilized in the study. A total of 100 typically developing school children aged between 5 and 9 years were divided into five age groups, each consisting of 10 males and 10 females. All children passed a hearing screening at 25 dB HL from 250 Hz to 4,000 Hz and had an average or above-average academic performance as reported by their teacher. All the children were tested using the developed tests. The order of administration of DPT and PPT was randomized. Children were instructed to listen to the sequence of vowel presentations and hum them in the same order. Results There was no significant difference between scores of males and females across all the age groups. On both tests, there was a significant improvement in the performance of the children with increase in age. There was a strong overall correlation between scores of DPT and PPT. Conclusion Both DPT and PPT, utilizing vowels as stimuli, did not exhibit a ceiling effect. This study highlighted a robust correlation between the two tests.

3D morphology of an outer-hair-cell hair bundle increases its displacement and dynamic range

In mammals, outer-hair-cell hair bundles (OHBs) transduce sound-induced forces into receptor currents and are required for the wide dynamic range and high sensitivity of hearing. OHBs differ conspicuously in morphology from other types of bundles. Here, we show that the 3D morphology of an OHB greatly impacts its mechanics and transduction. An OHB comprises rod-like stereocilia, which pivot on the surface of its sensory outer hair cell. Stereocilium pivot positions are arranged in columns and form a V shape. We measure the pivot positions and determine that OHB columns are far from parallel. To calculate the consequences of an OHB’s V shape and far-from-parallel columns, we develop a mathematical model of an OHB that relates its pivot positions, 3D morphology, mechanics, and receptor current. We find that the 3D morphology of the OHB can halve its stiffness, can double its damping coefficient, and causes stereocilium displacements driven by stimulus forces to differ substantially across the OHB. Stereocilium displacements drive the opening and closing of ion channels through which the receptor current flows. Owing to the stereocilium-displacement differences, the currents passing through the ion channels can peak versus the stimulus frequency and vary considerably across the OHB. Consequently, the receptor current peaks versus the stimulus frequency. Ultimately, the OHB’s 3D morphology can increase its receptor-current dynamic range more than twofold. Our findings imply that potential pivot-position changes owing to development, mutations, or location within the mammalian auditory organ might greatly alter OHB function.

An Extensive Parametric Analysis and Optimization to Design Unidimensional Periodic Acoustic Metamaterials for Noise Attenuation

The presented research delineates an extensive study aimed at obtaining and comparing optimal designs and geometries for one-dimensional periodic acoustic metamaterials to attenuate noise within the audible frequency range of 20 Hz to 20 kHz. Various periodic designs, encompassing diverse geometric parameters and shapes—from Basic-Periodic to Semi-Periodic, Tapered-Diverging, and Tapered-Converging unit cells of repeated patterns—are examined to identify the most effective configurations for this application. A thorough parametric analysis is executed employing FE-Bloch’s theorem across these four configurations to determine their bandgaps and to identify the most effective geometry. A normalization process is utilized to extend the domain of the analysis and the range of the system parameters studied in this work, totaling 202,505 design cases. Finally, the optimal design is identified based on achieving the best bandgaps coverage. The study concludes with the presentation of frequency domain acoustic pressure responses at multiple sensing points along the filters, validating the performance and the obtained bandgaps through these optimal geometries.

AcousTac: Tactile Sensing with Acoustic Resonance for Electronics-Free Soft Skin.

Sound is a rich information medium that transmits through air; people communicate through speech and can even discern material through tapping and listening. To capture frequencies in the human hearing range, commercial microphones typically have a sampling rate of over 40 kHz. These accessible acoustic technologies are not yet widely adopted for the explicit purpose of giving robots a sense of touch. Some researchers have used sound to sense tactile information, both monitoring ambient soundscape and with embedded speakers and microphones to measure sounds within structures. However, these options commonly do not provide a direct measure of steady state force or require electronics integrated somewhere near the contact location. In this work, we present AcousTac, an acoustic tactile sensor for electronics-free, force-sensitive soft skin. Compliant silicone caps and plastic tubes compose the resonant chambers that emit pneumatic-driven sound measurable with a conventional off-board microphone. The resulting frequency changes depend on the external loads on the compliant endcaps. The compliant cap vibrates with the resonant pressure waves and is a nonidealized boundary condition, initially producing a nonmonotonic force response. We characterize two solutions-adding a distal hole and mass to the cap-resulting in monotonic and nonhysteretic force readings with this technology. We can tune each AcousTac taxel to specific force and frequency ranges, based on geometric parameters including tube length, and thus uniquely sense each taxel simultaneously in an array. We demonstrate AcousTac's functionality on two robotic systems: a 4-taxel array and a 3-taxel astrictive gripper. Simple to implement with off-the-shelf parts, AcousTac is a promising concept for force sensing on soft robotic surfaces, especially in situations where electronics near the contact are not suitable. Equipping robots with tactile sensing and soft skin provides them with a sense of touch and the ability to safely interact with their surroundings.

Timbral brightness perception investigated through multimodal interference

Brightness is among the most studied aspects of timbre perception. Psychoacoustically, sounds described as “bright” versus “dark” typically exhibit a high versus low frequency emphasis in the spectrum. However, relatively little is known about the neurocognitive mechanisms that facilitate these metaphors we listen with. Do they originate in universal magnitude representations common to more than one sensory modality? Triangulating three different interaction paradigms, we investigated using speeded classification whether intramodal, crossmodal, and amodal interference occurs when timbral brightness, as modeled by the centroid of the spectral envelope, and pitch height/visual brightness/numerical value processing are semantically congruent and incongruent. In four online experiments varying in priming strategy, onset timing, and response deadline, 189 total participants were presented with a baseline stimulus (a pitch, gray square, or numeral) then asked to quickly identify a target stimulus that is higher/lower, brighter/darker, or greater/less than the baseline after being primed with a bright or dark synthetic harmonic tone. Results suggest that timbral brightness modulates the perception of pitch and possibly visual brightness, but not numerical value. Semantically incongruent pitch height-timbral brightness shifts produced significantly slower reaction time (RT) and higher error compared to congruent pairs. In the visual task, incongruent pairings of gray squares and tones elicited slower RTs than congruent pairings (in two experiments). No interference was observed in the number comparison task. These findings shed light on the embodied and multimodal nature of experiencing timbre.

Perception and imitation of period-doubled phonation: Pitch and voice qualitya).

Period-doubled phonation, henceforth, period doubling, characterized by voicing periods that alternate in amplitudes and/or frequencies, is often perceived rough and with an indeterminate pitch. Lower pitch percept has been suggested by past studies when the degree of amplitude or frequency modulation increases. However, how listeners use period doubling when identifying linguistic tones remains unclear. The current study uses tasks of categorization with training, followed by imitation of tones manipulated with period doubling (with amplitude and frequency modulation, both separately and jointly) in a novel language. Native Mandarin and English speakers with different levels of music experience were tested. I show that period doubling leads to a low-tone bias in perception and imitation, especially as the modulation degree, particularly that of frequency, increases. Interestingly, interactions with stimulus f0 and modulation type show that in amplitude-modulated tokens, when compared to lower f0 (200 Hz), higher f0 (300 Hz) drives more low-tone responses. Period doubling is also imitated with lowered f0 and creaky quality. Language and music experience does not affect perceptual and imitative responses, suggesting that the perception of period doubling is not language-specific or conditioned by tonal knowledge. Period doubling likely signals low tones, even when the original f0 is high.

Cochlear Implantation in Single-Sided Deafness and Asymmetric Hearing Loss: 12 Months Follow-up Results of a European Multicenter Evaluation.

People with single-sided deafness (SSD) or asymmetric hearing loss (AHL) have particular difficulty understanding speech in noisy listening situations and in sound localization. The objective of this multicenter study is to evaluate the effect of a cochlear implant (CI) in adults with single-sided deafness (SSD) or asymmetric hearing loss (AHL), particularly regarding sound localization and speech intelligibility with additional interest in electric-acoustic pitch matching. A prospective longitudinal study at 7 European tertiary referral centers was conducted including 19 SSD and 16 AHL subjects undergoing cochlear implantation. Sound localization accuracy was investigated in terms of root mean square error and signed bias before and after implantation. Speech recognition in quiet and speech reception thresholds in noise for several spatial configurations were assessed preoperatively and at several post-activation time points. Pitch perception with CI was tracked using pitch matching. Data up to 12 months post activation were collected. In both SSD and AHL subjects, CI significantly improved sound localization for sound sources on the implant side, and thus overall sound localization. Speech recognition in quiet with the implant ear improved significantly. In noise, a significant head shadow effect was found for SSD subjects only. However, the evaluation of AHL subjects was limited by the small sample size. No uniform development of pitch perception with the implant ear was observed. The benefits shown in this study confirm and expand the existing body of evidence for the effectiveness of CI in SSD and AHL. Particularly, improved localization was shown to result from increased localization accuracy on the implant side.

Deficits in congenital amusia: Pitch, music, speech, and beyond

Congenital amusia is a neurodevelopmental disorder characterized by deficits of music perception and production, which are related to altered pitch processing. The present study used a wide variety of tasks to test potential patterns of processing impairment in individuals with congenital amusia (N = 18) in comparison to matched controls (N = 19), notably classical pitch processing tests (i.e., pitch change detection, pitch direction of change identification, and pitch short-term memory tasks) together with tasks assessing other aspects of pitch-related auditory cognition, such as emotion recognition in speech, sound segregation in tone sequences, and speech-in-noise perception. Additional behavioral measures were also collected, including text reading/copying tests, visual control tasks, and a subjective assessment of hearing abilities. As expected, amusics' performance was impaired for the three pitch-specific tasks compared to controls. This deficit of pitch perception had a self-perceived impact on amusics’ quality of hearing. Moreover, participants with amusia were impaired in emotion recognition in vowels compared to controls, but no group difference was observed for emotion recognition in sentences, replicating previous data. Despite pitch processing deficits, participants with amusia did not differ from controls in sound segregation and speech-in-noise perception. Text reading and visual control tests did not reveal any impairments in participants with amusia compared to controls. However, the copying test revealed more numerous eye-movements and a smaller memory span. These results allow us to refine the pattern of pitch processing and memory deficits in congenital amusia, thus contributing further to understand pitch-related auditory cognition. Together with previous reports suggesting a comorbidity between congenital amusia and dyslexia, the findings call for further investigation of language-related abilities in this disorder even in the absence of neurodevelopmental language disorder diagnosis.

Screened optimally tuned range separated hybrid functional for solvated low bandgap molecular systems.

The description of electronic properties of low bandgap molecular system is often performed by using density functional theory (DFT) and time dependent (TD) DFT calculations with the optimally tuned range-separated hybrid (OT-RSH) functional, as it contains the necessary ingredients to reliably predict charge transfer excitations. However, the range separating parameter (ω) is system-dependent and its optimization, including the chemical environment, is intricate. Refaely-Abramson et al. demonstrated that the gap renormalization in molecular crystals, a ground state property, can be represented by an OT-RSH functional screened by ɛstatic [Phys. Rev. B 88, 081204(R) (2013)], the zero frequency scalar dielectric constant. In this study, we propose the use of an OT-RSH functional screened by the scalar dielectric constant in the high frequency limit (OT-sRSH), ɛ∞, an appropriate constraint for vertical ionization energies or excitations in a dielectric environment. We have performed calculations for S,N-heteroacene derivatives in tetrahydrofuran and dichloromethane. The "unscreened" OT-RSH functional tends to underestimate experimental ionization potentials (IPs) and optical gaps (Egs) by up to 1.5 and 0.5eV, respectively. In contrast, OT-sRSH functional calculations underestimate IPs and Egs by only 0.4 and 0.2eV. We also compared the OT-sRSH results to explicitly solvated OT-RSH functional calculations for oligothiophenes in dioxane, benzene in ammonia, and methylene blue in water. We observe that both the approaches perform similarly for weakly interacting intermolecular systems and deviate for solvent-solute interacting systems, as expected. In conclusion, the OT-sRSH functional can describe molecular systems with environmental polarization effects accurately, a step toward describing realistic molecular systems.

A Narrative Analysis of J. G. Roederer’s The Physics and Psychophysics of Music

This paper conducts narrative analysis for the rhetorical critique of Roederer's <i>The Physics and Psychophysics of Music</i>, a prominent textbook of music science. It is possible to analyze implicit narratives even for texts in non-narrative genres. In science textbooks, implicit narratives can be analyzed in structural, educational, and research contexts. Roederer's satisfies structural coherence by composing a book in a way that deals with the perception of pitch, volume, timbre, and harmony according to the stages of sound generation, transmission, and acceptance in a structural context. In an educational context, a book is composed of content that students may be interested in for a scientific understanding of music to satisfy material coherence, and the validity of narrative fidelity is satisfied through the pursuit of reliable knowledge through experience data and improved observational equipment according to the method of constructing scientific knowledge. From the research context, we can confirmed that characterological coherence is secured by satisfying the truthfulness of narrative fidelity through the update of knowledge throughout the four editions, and by revealing that the knowledge of music science is being built through the activities of major researchers.

The cochlear hook region detects harmonics beyond the canonical hearing range.

Ultrasound, or sound at frequencies exceeding the conventional range of human hearing, is not only audible to mice, microbats, and dolphins, but also creates an auditory sensation when delivered through bone conduction in humans. Although ultrasound is utilized for brain activation and in hearing aids, the physiological mechanism of ultrasonic hearing remains unknown. In guinea pigs, we found that ultrasound above the hearing range delivered through ossicles of the middle ear evokes an auditory brainstem response and a mechano-electrical transduction current through hair cells, as shown by the local field potential called the cochlear microphonic potential (CM). The CM synchronizes with ultrasound, and like the response to audible sounds is actively and nonlinearly amplified. In vivo optical nano-vibration analysis revealed that the sensory epithelium in the hook region, the basal extreme of the cochlear turns, resonates in response both to ultrasound within the hearing range and to harmonics beyond the hearing range. The results indicate that hair cells can respond to stimulation at the optimal frequency and its harmonics, and the hook region detects ultrasound stimuli with frequencies more than two octaves higher than the upper limit of the ordinary hearing range.

Distortions in sound: Bridging acoustics and psychoacoustics in auditory perception

The field of acoustics encompasses the examination of sound, encompassing both its physical characteristics and the way in which humans perceive auditory input. Acoustics is the study of how sound waves are created and spread physically, while psychoacoustics connects these physical characteristics to our auditory perceptions. Comprehending these two features is essential for progress in audio technology and understanding auditory perception aberrations such as paracusia and diplacusis. This research consolidates information from multiple investigations to examine the interaction between acoustics and psychoacoustics. The technique entails examining the current body of literature on the fundamental principles governing sound waves, their interaction with various materials, and their movement across space. The examination of psychoacoustic elements involved the conversion of sound waves into brain impulses. The study also examines certain psychoacoustic phenomena, such as the sense of pitch and auditory distortions. By combining acoustic and psychoacoustic concepts, we can gain a thorough comprehension of how we perceive sound. Sound waves, generated by mechanical vibrations, pass through substances such as air, causing compression and rarefaction cycles that move at a speed of about 344 m/s at a temperature of 20°C. Psychoacoustics studies the perception of sound waves, specifically how they are processed by the ear and converted into neural signals that the brain can understand. The key findings reveal the subjective nature of pitch perception, where alterations in intensity or length impact the perceived frequency and the precise sensitivity of pitch discrimination. Furthermore, abnormalities such as paracusia and diplacusis emphasize the intricacies of auditory perception. The study highlights the significance of psychoacoustics in audio technology, where principles are utilized in audio compression and noise reduction to improve sound quality and clarity. The comprehensive comprehension of acoustics and psychoacoustics lays the groundwork for advancements in audio technology and the creation of auditory experiences.

Auditory cortical regions show resting-state functional connectivity with the default mode-like network in echolocating bats

Echolocating bats are among the most social and vocal of all mammals. These animals are ideal subjects for functional MRI (fMRI) studies of auditory social communication given their relatively hypertrophic limbic and auditory neural structures and their reduced ability to hear MRI gradient noise. Yet, no resting-state networks relevant to social cognition (e.g., default mode-like networks or DMLNs) have been identified in bats since there are few, if any, fMRI studies in the chiropteran order. Here, we acquired fMRI data at 7 Tesla from nine lightly anesthetized pale spear-nosed bats (Phyllostomus discolor). We applied independent components analysis (ICA) to reveal resting-state networks and measured neural activity elicited by noise ripples (on: 10 ms; off: 10 ms) that span this species' ultrasonic hearing range (20 to 130 kHz). Resting-state networks pervaded auditory, parietal, and occipital cortices, along with the hippocampus, cerebellum, basal ganglia, and auditory brainstem. Two midline networks formed an apparent DMLN. Additionally, we found four predominantly auditory/parietal cortical networks, of which two were left-lateralized and two right-lateralized. Regions within four auditory/parietal cortical networks are known to respond to social calls. Along with the auditory brainstem, regions within these four cortical networks responded to ultrasonic noise ripples. Iterative analyses revealed consistent, significant functional connectivity between the left, but not right, auditory/parietal cortical networks and DMLN nodes, especially the anterior-most cingulate cortex. Thus, a resting-state network implicated in social cognition displays more distributed functional connectivity across left, relative to right, hemispheric cortical substrates of audition and communication in this highly social and vocal species.