Mean-based neural coding of voices

Anti-phasic oscillatory development for speech and noise processing in cochlear implanted toddlers

Human brain demonstrates amazing readiness for speech and language learning at birth, but the auditory development preceding such readiness remains unknown. Cochlear implanted (CI) children (n = 67; mean age 2.77 year ± 1.31 SD; 28 females) with prelingual deafness provide a unique opportunity to study this stage. Using functional near-infrared spectroscopy, it was revealed that the brain of CI children was irresponsive to sounds at CI hearing onset. With increasing CI experiences up to 32 months, the brain demonstrated function, region and hemisphere specific development. Most strikingly, the left anterior temporal lobe showed an oscillatory trajectory, changing in opposite phases for speech and noise. The study provides the first longitudinal brain imaging evidence for early auditory development preceding speech acquisition.

Unveiling the development of human voice perception: Neurobiological mechanisms and pathophysiology

The human voice is a critical stimulus for the auditory system that promotes social connection, informs the listener about identity and emotion, and acts as the carrier for spoken language. Research on voice processing in adults has informed our understanding of the unique status of the human voice in the mature auditory cortex and provided potential explanations for mechanisms that underly voice selectivity and identity processing. There is evidence that voice perception undergoes developmental change starting in infancy and extending through early adolescence. While even young infants recognize the voice of their mother, there is an apparent protracted course of development to reach adult-like selectivity for human voice over other sound categories and recognition of other talkers by voice. Gaps in the literature do not allow for an exact mapping of this trajectory or an adequate description of how voice processing and its neural underpinnings abilities evolve. This review provides a comprehensive account of developmental voice processing research published to date and discusses how this evidence fits with and contributes to current theoretical models proposed in the adult literature. We discuss how factors such as cognitive development, neural plasticity, perceptual narrowing, and language acquisition may contribute to the development of voice processing and its investigation in children. We also review evidence of voice processing abilities in premature birth, autism spectrum disorder, and phonagnosia to examine where and how deviations from the typical trajectory of development may manifest.

The effect of voice familiarity on attention to speech in a cocktail party scenario

Selective attention to one speaker in multi-talker environments can be affected by the acoustic and semantic properties of speech. One highly ecological feature of speech that has the potential to assist in selective attention is voice familiarity. Here, we tested how voice familiarity interacts with selective attention by measuring the neural speech-tracking response to both target and non-target speech in a dichotic listening "Cocktail Party" paradigm. We measured Magnetoencephalography from n = 33 participants, presented with concurrent narratives in two different voices, and instructed to pay attention to one ear ("target") and ignore the other ("non-target"). Participants were familiarized with one of the voices during the week prior to the experiment, rendering this voice familiar to them. Using multivariate speech-tracking analysis we estimated the neural responses to both stimuli and replicate their well-established modulation by selective attention. Importantly, speech-tracking was also affected by voice familiarity, showing enhanced response for target speech and reduced response for non-target speech in the contra-lateral hemisphere, when these were in a familiar vs. an unfamiliar voice. These findings offer valuable insight into how voice familiarity, and by extension, auditory-semantics, interact with goal-driven attention, and facilitate perceptual organization and speech processing in noisy environments.

Is song processing distinct and special in the auditory cortex?

Is the singing voice processed distinctively in the human brain? In this Perspective, we discuss what might distinguish song processing from speech processing in light of recent work suggesting that some cortical neuronal populations respond selectively to song and we outline the implications for our understanding of auditory processing. We review the literature regarding the neural and physiological mechanisms of song production and perception and show that this provides evidence for key differences between song and speech processing. We conclude by discussing the significance of the notion that song processing is special in terms of how this might contribute to theories of the neurobiological origins of vocal communication and to our understanding of the neural circuitry underlying sound processing in the human cortex.

Right Posterior Temporal Cortex Supports Integration of Phonetic and Talker Information

Though the right hemisphere has been implicated in talker processing, it is thought to play a minimal role in phonetic processing, at least relative to the left hemisphere. Recent evidence suggests that the right posterior temporal cortex may support learning of phonetic variation associated with a specific talker. In the current study, listeners heard a male talker and a female talker, one of whom produced an ambiguous fricative in /s/-biased lexical contexts (e.g., epi?ode) and one who produced it in /∫/-biased contexts (e.g., friend?ip). Listeners in a behavioral experiment (Experiment 1) showed evidence of lexically guided perceptual learning, categorizing ambiguous fricatives in line with their previous experience. Listeners in an fMRI experiment (Experiment 2) showed differential phonetic categorization as a function of talker, allowing for an investigation of the neural basis of talker-specific phonetic processing, though they did not exhibit perceptual learning (likely due to characteristics of our in-scanner headphones). Searchlight analyses revealed that the patterns of activation in the right superior temporal sulcus (STS) contained information about who was talking and what phoneme they produced. We take this as evidence that talker information and phonetic information are integrated in the right STS. Functional connectivity analyses suggested that the process of conditioning phonetic identity on talker information depends on the coordinated activity of a left-lateralized phonetic processing system and a right-lateralized talker processing system. Overall, these results clarify the mechanisms through which the right hemisphere supports talker-specific phonetic processing.

Brain mechanism of unfamiliar and familiar voice processing: an activation likelihood estimation meta-analysis

Interpersonal communication through vocal information is very important for human society. During verbal interactions, our vocal cord vibrations convey important information regarding voice identity, which allows us to decide how to respond to speakers (e.g., neither greeting a stranger too warmly or speaking too coldly to a friend). Numerous neural studies have shown that identifying familiar and unfamiliar voices may rely on different neural bases. However, the mechanism underlying voice identification of individuals of varying familiarity has not been determined due to vague definitions, confusion of terms, and differences in task design. To address this issue, the present study first categorized three kinds of voice identity processing (perception, recognition and identification) from speakers with different degrees of familiarity. We defined voice identity perception as passively listening to a voice or determining if the voice was human, voice identity recognition as determining if the sound heard was acoustically familiar, and voice identity identification as ascertaining whether a voice is associated with a name or face. Of these, voice identity perception involves processing unfamiliar voices, and voice identity recognition and identification involves processing familiar voices. According to these three definitions, we performed activation likelihood estimation (ALE) on 32 studies and revealed different brain mechanisms underlying processing of unfamiliar and familiar voice identities. The results were as follows: (1) familiar voice recognition/identification was supported by a network involving most regions in the temporal lobe, some regions in the frontal lobe, subcortical structures and regions around the marginal lobes; (2) the bilateral superior temporal gyrus was recruited for voice identity perception of an unfamiliar voice; (3) voice identity recognition/identification of familiar voices was more likely to activate the right frontal lobe than voice identity perception of unfamiliar voices, while voice identity perception of an unfamiliar voice was more likely to activate the bilateral temporal lobe and left frontal lobe; and (4) the bilateral superior temporal gyrus served as a shared neural basis of unfamiliar voice identity perception and familiar voice identity recognition/identification. In general, the results of the current study address gaps in the literature, provide clear definitions of concepts, and indicate brain mechanisms for subsequent investigations.

Early differentiation of memory retrieval processes for newly learned voices and phonemes as indexed by the MMN

Linguistic and vocal information are thought to be differentially processed since the early stages of speech perception, but it remains unclear if this differentiation also concerns automatic processes of memory retrieval. The aim of this ERP study was to compare the automatic retrieval processes for newly learned voices vs phonemes. In a longitudinal experiment, two groups of participants were trained in learning either a new phoneme or a new voice. The MMN elicited by the presentation of the two was measured before and after the training. An enhanced MMN was elicited by the presentation of the learned phoneme, reflecting the activation of an automatic memory retrieval process. Instead, a reduced MMN was elicited by the learned voice, indicating that the voice was perceived as a typical member of the learned voice identity. This suggests that the automatic processes that retrieve linguistic and vocal information are differently affected by experience.

Social relationship-dependent neural response to speech in dogs

In humans, social relationship with the speaker affects neural processing of speech, as exemplified by children's auditory and reward responses to their mother's utterances. Family dogs show human analogue attachment behavior towards the owner, and neuroimaging revealed auditory cortex and reward center sensitivity to verbal praises in dog brains. Combining behavioral and non-invasive fMRI data, we investigated the effect of dogs' social relationship with the speaker on speech processing. Dogs listened to praising and neutral speech from their owners and a control person. We found positive correlation between dogs' behaviorally measured attachment scores towards their owners and neural activity increase for the owner's voice in the caudate nucleus; and activity increase in the secondary auditory caudal ectosylvian gyrus and the caudate nucleus for the owner's praise. Through identifying social relationship-dependent neural reward responses, our study reveals similarities in neural mechanisms modulated by infant-mother and dog-owner attachment.

Categorizing human vocal signals depends on an integrated auditory-frontal cortical network

Voice signals are relevant for auditory communication and suggested to be processed in dedicated auditory cortex (AC) regions. While recent reports highlighted an additional role of the inferior frontal cortex (IFC), a detailed description of the integrated functioning of the AC-IFC network and its task relevance for voice processing is missing. Using neuroimaging, we tested sound categorization while human participants either focused on the higher-order vocal-sound dimension (voice task) or feature-based intensity dimension (loudness task) while listening to the same sound material. We found differential involvements of the AC and IFC depending on the task performed and whether the voice dimension was of task relevance or not. First, when comparing neural vocal-sound processing of our task-based with previously reported passive listening designs we observed highly similar cortical activations in the AC and IFC. Second, during task-based vocal-sound processing we observed voice-sensitive responses in the AC and IFC whereas intensity processing was restricted to distinct AC regions. Third, the IFC flexibly adapted to the vocal-sounds' task relevance, being only active when the voice dimension was task relevant. Forth and finally, connectivity modeling revealed that vocal signals independent of their task relevance provided significant input to bilateral AC. However, only when attention was on the voice dimension, we found significant modulations of auditory-frontal connections. Our findings suggest an integrated auditory-frontal network to be essential for behaviorally relevant vocal-sounds processing. The IFC seems to be an important hub of the extended voice network when representing higher-order vocal objects and guiding goal-directed behavior.

Expectancy changes the self-monitoring of voice identity

Self‐voice attribution can become difficult when voice characteristics are ambiguous, but functional magnetic resonance imaging (fMRI) investigations of such ambiguity are sparse. We utilized voice‐morphing (self‐other) to manipulate (un‐)certainty in self‐voice attribution in a button‐press paradigm. This allowed investigating how levels of self‐voice certainty alter brain activation in brain regions monitoring voice identity and unexpected changes in voice playback quality. FMRI results confirmed a self‐voice suppression effect in the right anterior superior temporal gyrus (aSTG) when self‐voice attribution was unambiguous. Although the right inferior frontal gyrus (IFG) was more active during a self‐generated compared to a passively heard voice, the putative role of this region in detecting unexpected self‐voice changes during the action was demonstrated only when hearing the voice of another speaker and not when attribution was uncertain. Further research on the link between right aSTG and IFG is required and may establish a threshold monitoring voice identity in action. The current results have implications for a better understanding of the altered experience of self‐voice feedback in auditory verbal hallucinations.

The Role of the Right Hemisphere in Processing Phonetic Variability Between Talkers

Neurobiological models of speech perception posit that both left and right posterior temporal brain regions are involved in the early auditory analysis of speech sounds. However, frank deficits in speech perception are not readily observed in individuals with right hemisphere damage. Instead, damage to the right hemisphere is often associated with impairments in vocal identity processing. Herein lies an apparent paradox: The mapping between acoustics and speech sound categories can vary substantially across talkers, so why might right hemisphere damage selectively impair vocal identity processing without obvious effects on speech perception? In this review, I attempt to clarify the role of the right hemisphere in speech perception through a careful consideration of its role in processing vocal identity. I review evidence showing that right posterior superior temporal, right anterior superior temporal, and right inferior / middle frontal regions all play distinct roles in vocal identity processing. In considering the implications of these findings for neurobiological accounts of speech perception, I argue that the recruitment of right posterior superior temporal cortex during speech perception may specifically reflect the process of conditioning phonetic identity on talker information. I suggest that the relative lack of involvement of other right hemisphere regions in speech perception may be because speech perception does not necessarily place a high burden on talker processing systems, and I argue that the extant literature hints at potential subclinical impairments in the speech perception abilities of individuals with right hemisphere damage.

Multilevel fMRI adaptation for spoken word processing in the awake dog brain

Human brains process lexical meaning separately from emotional prosody of speech at higher levels of the processing hierarchy. Recently we demonstrated that dog brains can also dissociate lexical and emotional prosodic information in human spoken words. To better understand the neural dynamics of lexical processing in the dog brain, here we used an event-related design, optimized for fMRI adaptation analyses on multiple time scales. We investigated repetition effects in dogs’ neural (BOLD) responses to lexically marked (praise) words and to lexically unmarked (neutral) words, in praising and neutral prosody. We identified temporally and anatomically distinct adaptation patterns. In a subcortical auditory region, we found both short- and long-term fMRI adaptation for emotional prosody, but not for lexical markedness. In multiple cortical auditory regions, we found long-term fMRI adaptation for lexically marked compared to unmarked words. This lexical adaptation showed right-hemisphere bias and was age-modulated in a near-primary auditory region and was independent of prosody in a secondary auditory region. Word representations in dogs’ auditory cortex thus contain more than just the emotional prosody they are typically associated with. These findings demonstrate multilevel fMRI adaptation effects in the dog brain and are consistent with a hierarchical account of spoken word processing.

Expectations about word stress modulate neural activity in speech-sensitive cortical areas

A recent dual-stream model of language processing proposed that the postero-dorsal stream performs predictive sequential processing of linguistic information via hierarchically organized internal models. However, it remains unexplored whether the prosodic segmentation of linguistic information involves predictive processes. Here, we addressed this question by investigating the processing of word stress, a major component of speech segmentation, using probabilistic repetition suppression (RS) modulation as a marker of predictive processing. In an event-related acoustic fMRI RS paradigm, we presented pairs of pseudowords having the same (Rep) or different (Alt) stress patterns, in blocks with varying Rep and Alt trial probabilities. We found that the BOLD signal was significantly lower for Rep than for Alt trials, indicating RS in the posterior and middle superior temporal gyrus (STG) bilaterally, and in the anterior STG in the left hemisphere. Importantly, the magnitude of RS was modulated by repetition probability in the posterior and middle STG. These results reveal the predictive processing of word stress in the STG areas and raise the possibility that words stress processing is related to the dorsal "where" auditory stream.

Self-voice perception and its relationship with hallucination predisposition

Introduction: Auditory verbal hallucinations (AVH) are a core symptom of psychotic disorders such as schizophrenia but are also reported in 10-15% of the general population. Impairments in self-voice recognition are frequently reported in schizophrenia and associated with the severity of AVH, particularly when the self-voice has a negative quality. However, whether self-voice processing is also affected in nonclinical voice hearers remains to be specified. Methods: Thirty-five nonclinical participants varying in hallucination predisposition based on the Launay-Slade Hallucination Scale, listened to prerecorded words and vocalisations differing in identity (self/other) and emotional quality. In Experiment 1, participants indicated whether words were spoken in their own voice, another voice, or whether they were unsure (recognition task). They were also asked whether pairs of words/vocalisations were uttered by the same or by a different speaker (discrimination task). In Experiment 2, participants judged the emotional quality of the words/vocalisations. Results: In Experiment 1, hallucination predisposition affected voice discrimination and recognition, irrespective of stimulus valence. Hallucination predisposition did not affect the evaluation of the emotional valence of words/vocalisations (Experiment 2). Conclusions: These findings suggest that nonclinical participants with high HP experience altered voice identity processing, whereas HP does not affect the perception of vocal emotion. Specific alterations in self-voice perception in clinical and nonclinical voice hearers may establish a core feature of the psychosis continuum.

Speaker-normalized sound representations in the human auditory cortex

The acoustic dimensions that distinguish speech sounds (like the vowel differences in "boot" and "boat") also differentiate speakers' voices. Therefore, listeners must normalize across speakers without losing linguistic information. Past behavioral work suggests an important role for auditory contrast enhancement in normalization: preceding context affects listeners' perception of subsequent speech sounds. Here, using intracranial electrocorticography in humans, we investigate whether and how such context effects arise in auditory cortex. Participants identified speech sounds that were preceded by phrases from two different speakers whose voices differed along the same acoustic dimension as target words (the lowest resonance of the vocal tract). In every participant, target vowels evoke a speaker-dependent neural response that is consistent with the listener's perception, and which follows from a contrast enhancement model. Auditory cortex processing thus displays a critical feature of normalization, allowing listeners to extract meaningful content from the voices of diverse speakers.

Neural processes of vocal social perception: Dog-human comparative fMRI studies

In this review we focus on the exciting new opportunities in comparative neuroscience to study neural processes of vocal social perception by comparing dog and human neural activity using fMRI methods. The dog is a relatively new addition to this research area; however, it has a large potential to become a standard species in such investigations. Although there has been great interest in the emergence of human language abilities, in case of fMRI methods, most research to date focused on homologue comparisons within Primates. By belonging to a very different clade of mammalian evolution, dogs could give such research agendas a more general mammalian foundation. In addition, broadening the scope of investigations into vocal communication in general can also deepen our understanding of human vocal skills. Being selected for and living in an anthropogenic environment, research with dogs may also be informative about the way in which human non-linguistic and linguistic signals are represented in a mammalian brain without skills for language production.

Functional connectivity within the voice perception network and its behavioural relevance

Recognizing who is speaking is a cognitive ability characterized by considerable individual differences, which could relate to the inter-individual variability observed in voice-elicited BOLD activity. Since voice perception is sustained by a complex brain network involving temporal voice areas (TVAs) and, even if less consistently, extra-temporal regions such as frontal cortices, functional connectivity (FC) during an fMRI voice localizer (passive listening of voices vs non-voices) has been computed within twelve temporal and frontal voice-sensitive regions (“voice patches”) individually defined for each subject (N = 90) to account for inter-individual variability. Results revealed that voice patches were positively co-activated during voice listening and that they were characterized by different FC pattern depending on the location (anterior/posterior) and the hemisphere. Importantly, FC between right frontal and temporal voice patches was behaviorally relevant: FC significantly increased with voice recognition abilities as measured in a voice recognition test performed outside the scanner. Hence, this study highlights the importance of frontal regions in voice perception and it supports the idea that looking at FC between stimulus-specific and higher-order frontal regions can help understanding individual differences in processing social stimuli such as voices.

A "voice patch" system in the primate brain for processing vocal information?

We review behavioural and neural evidence for the processing of information contained in conspecific vocalizations (CVs) in three primate species: humans, macaques and marmosets. We focus on abilities that are present and ecologically relevant in all three species: the detection and sensitivity to CVs; and the processing of identity cues in CVs. Current evidence, although fragmentary, supports the notion of a "voice patch system" in the primate brain analogous to the face patch system of visual cortex: a series of discrete, interconnected cortical areas supporting increasingly abstract representations of the vocal input. A central question concerns the degree to which the voice patch system is conserved in evolution. We outline challenges that arise and suggesting potential avenues for comparing the organization of the voice patch system across primate brains.

It doesn't matter what you say: FMRI correlates of voice learning and recognition independent of speech content

Listeners can recognize newly learned voices from previously unheard utterances, suggesting the acquisition of high-level speech-invariant voice representations during learning. Using functional magnetic resonance imaging (fMRI) we investigated the anatomical basis underlying the acquisition of voice representations for unfamiliar speakers independent of speech, and their subsequent recognition among novel voices. Specifically, listeners studied voices of unfamiliar speakers uttering short sentences and subsequently classified studied and novel voices as “old” or “new” in a recognition test. To investigate “pure” voice learning, i.e., independent of sentence meaning, we presented German sentence stimuli to non-German speaking listeners. To disentangle stimulus-invariant and stimulus-dependent learning, during the test phase we contrasted a “same sentence” condition in which listeners heard speakers repeating the sentences from the preceding study phase, with a “different sentence” condition. Voice recognition performance was above chance in both conditions although, as expected, performance was higher for same than for different sentences. During study phases activity in the left inferior frontal gyrus (IFG) was related to subsequent voice recognition performance and same versus different sentence condition, suggesting an involvement of the left IFG in the interactive processing of speaker and speech information during learning. Importantly, at test reduced activation for voices correctly classified as “old” compared to “new” emerged in a network of brain areas including temporal voice areas (TVAs) of the right posterior superior temporal gyrus (pSTG), as well as the right inferior/middle frontal gyrus (IFG/MFG), the right medial frontal gyrus, and the left caudate. This effect of voice novelty did not interact with sentence condition, suggesting a role of temporal voice-selective areas and extra-temporal areas in the explicit recognition of learned voice identity, independent of speech content.

Activation in the angular gyrus and in the pSTS is modulated by face primes during voice recognition

The aim of the present study was to better understand the interaction of face and voice processing when identifying people. In a S1-S2 crossmodal priming fMRI experiment, the target (S2) was a disyllabic voice stimulus, whereas the modality of the prime (S1) was manipulated blockwise and consisted of the silent video of a speaking face in the crossmodal condition or of a voice stimulus in the unimodal condition. Primes and targets were from the same speaker (person-congruent) or from two different speakers (person-incongruent). Participants had to classify the S2 as either an old or a young person. Response times were shorter after a congruent than after an incongruent face prime. The right posterior superior temporal sulcus (pSTS) and the right angular gyrus showed a significant person identity effect (person-incongruent > person-congruent) in the crossmodal condition but not in the unimodal condition. In the unimodal condition, a person identity effect was observed in the bilateral inferior frontal gyrus. Our data suggest that both the priming with a voice and with a face result in a preactivated voice representation of the respective person, which eventually facilitates (person-congruent trials) or hampers (person-incongruent trials) the processing of the identity of a subsequent voice. This process involves activation in the right pSTS and in the right angular gyrus for voices primed by faces, but not for voices primed by voices. Hum Brain Mapp 38:2553-2565, 2017. © 2017 Wiley Periodicals, Inc.

Voice-sensitive brain networks encode talker-specific phonetic detail

The speech stream simultaneously carries information about talker identity and linguistic content, and the same acoustic property (e.g., voice-onset-time, or VOT) may be used for both purposes. Separable neural networks for processing talker identity and phonetic content have been identified, but it is unclear how a singular acoustic property is parsed by the neural system for talker identification versus phonetic processing. In the current study, listeners were exposed to two talkers with characteristically different VOTs. Subsequently, brain activation was measured using fMRI as listeners performed a phonetic categorization task on these stimuli. Right temporoparietal regions previously implicated in talker identification showed sensitivity to the match between VOT variant and talker, whereas left posterior temporal regions showed sensitivity to the typicality of phonetic exemplars, regardless of talker typicality. Taken together, these results suggest that neural systems for voice recognition capture talker-specific phonetic variation.

Structural Content in Paintings II: Artists Commissioned to Reproduce a Specific Image Over-Regularize Orientation Biases in Their Paintings

Measurements of psychophysical performance show that the visual system is biased in ways that counteract statistical regularities of natural scenes thereby allowing efficient coding. Here we consider the perceptual effects of these encoding biases in a “holistic” way by measuring characteristics of the paintings produced by artists making perceptual matches to a natural scene image; 10 artists were asked to produce an exact copy of a single outdoor landscape scene. The structural content of the paintings produced and the “ground truth” image were compared in the frequency domain. The artists were found to over-regularize the orientation content in the paintings: The anisotropy existing only at the lowest spatial scales in the natural scene image was produced across all spatial scales in these commissioned paintings. These results were compared to those from two other methods of comparing paintings and natural scenes reported previously in a companion paper and all three methodologies indicate very similar over-regularization. We suggest that artists may have a general canonical representation of structural relations of scenes that they apply broadly within their creations.

Multivariate sensitivity to voice during auditory categorization

Past neuroimaging studies have documented discrete regions of human temporal cortex that are more strongly activated by conspecific voice sounds than by nonvoice sounds. However, the mechanisms underlying this voice sensitivity remain unclear. In the present functional MRI study, we took a novel approach to examining voice sensitivity, in which we applied a signal detection paradigm to the assessment of multivariate pattern classification among several living and nonliving categories of auditory stimuli. Within this framework, voice sensitivity can be interpreted as a distinct neural representation of brain activity that correctly distinguishes human vocalizations from other auditory object categories. Across a series of auditory categorization tests, we found that bilateral superior and middle temporal cortex consistently exhibited robust sensitivity to human vocal sounds. Although the strongest categorization was in distinguishing human voice from other categories, subsets of these regions were also able to distinguish reliably between nonhuman categories, suggesting a general role in auditory object categorization. Our findings complement the current evidence of cortical sensitivity to human vocal sounds by revealing that the greatest sensitivity during categorization tasks is devoted to distinguishing voice from nonvoice categories within human temporal cortex.

A Neuropsychological Approach to Auditory Verbal Hallucinations and Thought Insertion - Grounded in Normal Voice Perception

A neuropsychological perspective on auditory verbal hallucinations (AVH) links key phenomenological features of the experience, such as voice location and identity, to functionally separable pathways in normal human audition. Although this auditory processing stream (APS) framework has proven valuable for integrating research on phenomenology with cognitive and neural accounts of hallucinatory experiences, it has not yet been applied to other symptoms presumed to be closely related to AVH – such as thought insertion (TI). In this paper, I propose that an APS framework offers a useful way of thinking about the experience of TI as well as AVH, providing a common conceptual framework for both. I argue that previous self-monitoring theories struggle to account for both the differences and similarities in the characteristic features of AVH and TI, which can be readily accommodated within an APS framework. Furthermore, the APS framework can be integrated with predictive processing accounts of psychotic symptoms; makes predictions about potential sites of prediction error signals; and may offer a template for understanding a range of other symptoms beyond AVH and TI.

Voice-sensitive regions in the dog and human brain are revealed by comparative fMRI

During the approximately 18-32 thousand years of domestication, dogs and humans have shared a similar social environment. Dog and human vocalizations are thus familiar and relevant to both species, although they belong to evolutionarily distant taxa, as their lineages split approximately 90-100 million years ago. In this first comparative neuroimaging study of a nonprimate and a primate species, we made use of this special combination of shared environment and evolutionary distance. We presented dogs and humans with the same set of vocal and nonvocal stimuli to search for functionally analogous voice-sensitive cortical regions. We demonstrate that voice areas exist in dogs and that they show a similar pattern to anterior temporal voice areas in humans. Our findings also reveal that sensitivity to vocal emotional valence cues engages similarly located nonprimary auditory regions in dogs and humans. Although parallel evolution cannot be excluded, our findings suggest that voice areas may have a more ancient evolutionary origin than previously known.