Deficits in voice-identity processing: Acquired and developmental phonagnosia

The voice contains elementary social communication cues, conveying speech, as well as paralinguistic information pertaining to the emotional state and the identity of the speaker. In contrast to vocal-speech and vocal-emotion processing, voice-identity processing has been less explored. This seems surprising, given the day-to-day significance of person recognition by voice. A valuable approach to unravel how voice-identity processing is accomplished is to investigate people who have a selective deficit in recognising voices. Such a deficit has been termed phonagnosia. In the present chapter, we provide a systematic overview of studies on phonagnosia and how they relate to current neurocognitive models of person recognition. We review studies that have characterised people who suffer from phonagnosia following brain damage (i.e. acquired phonagnosia) and also studies, which have examined phonagnosia cases without apparent brain lesion (i.e. developmental phonagnosia). Based on the reviewed literature, we emphasise the need for a careful behavioural characterisation of phonagnosia cases by taking into consideration the multistage nature of voice-identity processing and the resulting behavioural phonagnosia subtypes

Psychopathic and autistic traits differentially influence the neural mechanisms of social cognition from communication signals

Psychopathy is associated with severe deviations in social behavior and cognition. While previous research described such cognitive and neural alterations in the processing of rather specific social information from human expressions, some open questions remain concerning central and differential neurocognitive deficits underlying psychopathic behavior. Here we investigated three rather unexplored factors to explain these deficits, first, by assessing psychopathy subtypes in social cognition, second, by investigating the discrimination of social communication sounds (speech, non-speech) from other non-social sounds, and third, by determining the neural overlap in social cognition impairments with autistic traits, given potential common deficits in the processing of communicative voice signals. The study was exploratory with a focus on how psychopathic and autistic traits differentially influence the function of social cognitive and affective brain networks in response to social voice stimuli. We used a parametric data analysis approach from a sample of 113 participants (47 male, 66 female) with ages ranging between 18 and 40 years (mean 25.59, SD 4.79). Our data revealed four important findings. First, we found a phenotypical overlap between secondary but not primary psychopathy with autistic traits. Second, primary psychopathy showed various neural deficits in neural voice processing nodes (speech, non-speech voices) and in brain systems for social cognition (mirroring, mentalizing, empathy, emotional contagion). Primary psychopathy also showed deficits in the basal ganglia (BG) system that seems specific to the social decoding of communicative voice signals. Third, neural deviations in secondary psychopathy were restricted to social mirroring and mentalizing impairments, but with additional and so far undescribed deficits at the level of auditory sensory processing, potentially concerning deficits in ventral auditory stream mechanisms (auditory object identification). Fourth, high autistic traits also revealed neural deviations in sensory cortices, but rather in the dorsal auditory processing streams (communicative context encoding). Taken together, social cognition of voice signals shows considerable deviations in psychopathy, with differential and newly described deficits in the BG system in primary psychopathy and at the neural level of sensory processing in secondary psychopathy. These deficits seem especially triggered during the social cognition from vocal communication signals

The Glasgow Voice Memory Test: Assessing the ability to memorize and recognize unfamiliar voices

One thousand one hundred and twenty subjects as well as a developmental phonagnosic subject (KH) along with age-matched controls performed the Glasgow Voice Memory Test, which assesses the ability to encode and immediately recognize, through an old/new judgment, both unfamiliar voices (delivered as vowels, making language requirements minimal) and bell sounds. The inclusion of non-vocal stimuli allows the detection of significant dissociations between the two categories (vocal vs. non-vocal stimuli). The distributions of accuracy and sensitivity scores (d’) reflected a wide range of individual differences in voice recognition performance in the population. As expected, KH showed a dissociation between the recognition of voices and bell sounds, her performance being significantly poorer than matched controls for voices but not for bells. By providing normative data of a large sample and by testing a developmental phonagnosic subject, we demonstrated that the Glasgow Voice Memory Test, available online and accessible fromall over the world, can be a valid screening tool (~5 min) for a preliminary detection of potential cases of phonagnosia and of “super recognizers” for voices

Voice-Identity Processing Deficit - The Cognitive and Neural Mechanisms of Phonagnosia

Die Stimme ist reich an grundlegenden Kommunikationselementen: Sie transportiert Sprache, sowie auch paralinguistische Informationen, wie den emotionale Zustand und die Identität des Sprechers. Im Vergleich zur Sprach- und Emotionsverarbeitung ist die Stimmerkennung bei weitem weniger gut erforscht. Dies ist erstaunlich, angesichts der allgegenwärtigen Relevanz der stimmbasierten Personenerkennung. Ein Ansatz neue Erkenntnisse zur Stimmerkennung zu erlangen, ist die Untersuchung von Personen, die ein selektives Defizit in der Stimmerkennung aufweisen. Dieses Defizit wird Phonagnosie bezeichnet. In der vorliegenden Dissertation untersuche ich Personen, bei denen Phonagnosie nach einer Hirnschädigung aufgetreten ist (i.e. erworbene Phonagnosie) und Personen, bei denen Phonagnosie entwicklungsbedingt und nicht durch eine offensichtliche Hirnschädigung bedingt ist (i.e. entwicklungsbedingte Phonagnosie). Die zugrunde liegenden kognitiven, neuro-funktionalen und neuro-anatomischen Mechanismen der Phonagnosie habe ich detailliert mit Hilfe von umfangreichen Verhaltensuntersuchungen sowie funktionaler und struktureller Magnetresonanztomographie charakterisiert. Die Ergebnisse der Dissertation bereichern das derzeitige Stimmerkennungsmodel durch: (i) Neue Erkenntnisse darüber welche Gehirnregionen notwendig sind, um eine Stimme zu erkennen. (ii) Und durch die empirische Bekräftigung der Annahme, dass Stimmerkennung ein mehrstufiger kognitiver Prozess ist, der verschiedene Subformen der Phonagnosie bedingt. Darüber hinaus tragen neue wissenschaftliche Erkenntnisse zur Stimmerkennung maßgeblich dazu bei, praktische Anwendungsbereiche wie klinische Therapieprogramme und künstliche Stimmerkennungprogramme weiterzuentwickeln.The voice contains elementary social communication cues: it conveys speech, as well as paralinguistic information pertaining to the emotional state or the identity of the speaker. In contrast to neuroscientific research on vocal-speech and vocal-emotion processing, voice-identity processing has been less explored. This seems surprising, given the day-to-day significance of person recognition by voice. A valuable approach to unravel how voice-identity processing is accomplished is to investigate people who have a selective deficit in voice recognition. Such a deficit has been termed phonagnosia. In the present dissertation, I investigate phonagnosia following brain damage (i.e. acquired phonagnosia), as well as phonagnosia cases without apparent brain lesion (i.e. developmental phonagnosia). I in-depth characterise the underlying cognitive, neural-functional, and neuro-anatomical mechanisms of phonagnosia by means of comprehensive behavioural testing as well as functional and structural magnetic resonance imaging. The findings of this dissertation inform the current model of voice-identity processing by (i) delivering novel evidence of brain regions that crucially contribute to voice-identity processing, and by (ii) emphasising the multistage nature of voice-identity processing. We showed that dysfunction at different cognitive stages results in behaviourally distinct phonagnosia sub-types. Generally, advanced scientific knowledge about voice-identity processing as provided in the current dissertation also propels practical applications such as clinical treatment programs and artificial voice-recognition systems

Who is speaking? Cognitive and neural mechanisms of voice-identity processing

Human voice recognition is critical for social communication. However, the underlying mechanisms of voice-identity processing are relatively unknown so far. A valuable approach to unravel how voice-identity processing is accomplished in the human brain is to investigate people who have a selective deficit in recognising voices. Such a deficit has been termed phonagnosia. In this talk I will present findings from investigations on phonagnosia following brain damage (i.e. acquired phonagnosia) as well as phonagnosia cases without apparent brain lesion (i.e. developmental phonagnosia). We characterised the underlying cognitive, neural-functional, and neuro-anatomical mechanisms of phonagnosia by means of comprehensive behavioural testing, functional magnetic resonance imaging (fMRI), and voxel-based lesion symptom mapping (VLSM). Our findings inform current models of voice-identity processing by (i) delivering novel evidence of brain regions that crucially contribute to voice-identity processing, and by (ii) emphasising the multistage nature of voice-identity processing. We showed that dysfunction at different cognitive stages results in behaviourally distinct phonagnosia subtypes