Claudia Roswandowitz

Two cases of selective developmental voice-recognition impairments

Recognizing other individuals is an essential skill in humans and in other species. Over the last decade, it has become increasingly clear that person-identity recognition abilities are highly variable. Roughly 2% of the population has developmental prosopagnosia, a congenital deficit in recognizing others by their faces. It is currently unclear whether developmental phonagnosia, a deficit in recognizing others by their voices, is equally prevalent, or even whether it actually exists. Here, we aimed to identify cases of developmental phonagnosia. We collected more than 1,000 data sets from self-selected German individuals by using a web-based screening test that was designed to assess their voice-recognition abilities. We then examined potentially phonagnosic individuals by using a comprehensive laboratory test battery. We found two novel cases of phonagnosia: AS, a 32-year-old female, and SP, a 32-year-old male; both are otherwise healthy academics, have normal hearing, and show no pathological abnormalities in brain structure. The two cases have comparable patterns of impairments: both performed at least 2 SDs below the level of matched controls on tests that required learning new voices, judging the familiarity of famous voices, and discriminating pitch differences between voices. In both cases, only voice-identity processing per se was affected: face recognition, speech intelligibility, emotion recognition, and musical ability were all comparable to controls. The findings confirm the existence of developmental phonagnosia as a modality-specific impairment and allow a first rough prevalence estimate.

Voice identity processing in autism spectrum disorder

People with autism spectrum disorder (ASD) have difficulties in identifying another person by face and voice. This might contribute considerably to the development of social cognition and interaction difficulties. The characteristics of the voice recognition deficit in ASD are unknown. Here, we used a comprehensive behavioral test battery to systematically investigate voice processing in high‐functioning ASD (n = 16) and typically developed pair‐wise matched controls (n = 16). The ASD group had particular difficulties with discriminating, learning, and recognizing unfamiliar voices, while recognizing famous voices was relatively intact. Tests on acoustic processing abilities showed that the ASD group had a specific deficit in vocal pitch perception that was dissociable from otherwise intact acoustic processing (i.e., musical pitch, musical, and vocal timbre perception). Our results allow a characterization of the voice recognition deficit in ASD: The findings indicate that in high‐functioning ASD, the difficulty to recognize voices is particularly pronounced for learning novel voices and the recognition of unfamiliar peoples’ voices. This pattern might be indicative of difficulties with integrating the acoustic characteristics of the voice into a coherent percept—a function that has been previously associated with voice‐selective regions in the posterior superior temporal sulcus/gyrus of the human brain. Autism Res 2017, 10: 155–168.

Obligatory and facultative brain regions for voice-identity recognition

The brain structures critical for recognising another person’s voice remain unclear. Roswandowitz et al. report lesion-behaviour results showing that the right posterior/mid temporal lobe is obligatory for voice-identity recognition. The right inferior parietal lobe, in contrast, is required for voice-identity recognition only when face-identity information must also be processed.

Developmental phonagnosia: Linking neural mechanisms with the behavioural phenotype

ABSTRACT Human voice recognition is critical for many aspects of social communication. Recently, a rare disorder, developmental phonagnosia, which describes the inability to recognise a speakers voice, has been discovered. The underlying neural mechanisms are unknown. Here, we used two functional magnetic resonance imaging experiments to investigate brain function in two behaviourally well characterised phonagnosia cases, both 32 years old: AS has apperceptive and SP associative phonagnosia. We found distinct malfunctioned brain mechanisms in AS and SP matching their behavioural profiles. In apperceptive phonagnosia, right‐hemispheric auditory voice‐sensitive regions (i.e., Heschls gyrus, planum temporale, superior temporal gyrus) showed lower responses than in matched controls (nAS=16) for vocal versus non‐vocal sounds and for speaker versus speech recognition. In associative phonagnosia, the connectivity between voice‐sensitive (i.e. right posterior middle/inferior temporal gyrus) and supramodal (i.e. amygdala) regions was reduced in comparison to matched controls (nSP=16) during speaker versus speech recognition. Additionally, both cases recruited distinct potential compensatory mechanisms. Our results support a central assumption of current two‐system models of voice‐identity processing: They provide the first evidence that dysfunction of voice‐sensitive regions and impaired connectivity between voice‐sensitive and supramodal person recognition regions can selectively contribute to deficits in person recognition by voice.

P 15 Voice-identity processing deficits are induced by lesions in the temporal and inferior parietal lobe

Human voice recognition is an essential skill for social interactions. The mechanisms that the human brain uses for voice recognition are to-date unknown. According to studies in patients with brain lesions, voice recognition critically involves the bilateral temporal lobe and the right inferior parietal lobe. In contrast, functional magnetic resonance imaging (fMRI) studies suggest that primarily the right temporal lobe contributes to voice recognition. In order to systematically investigate brain regions required for voice recognition, we conducted a voxel-based lesion symptom mapping (VLSM) study. The study included a comprehensive behavioral test battery, neuropsychological assessment and high-resolution structural brain images. We tested 58 patients having unilateral focal brain lesions on unfamiliar and familiar voice recognition as well as face recognition skills. VLSM analysis revealed three key findings. (i) A strong association between right temporal and right inferior parietal lobe lesions and voice-recognition deficits. (ii) Only the association of the right temporal lobe with voice-recognition deficits remained significant when we controlled for face-recognition performance. (iii) Unfamiliar voice-recognition deficits were associated with lesions in the right temporal lobe as well as in the right inferior parietal lobe. The ability to recognize familiar voices was associated with left posterior temporal lobe lesions. Our results help to explain the discrepancies between previous lesion and fMRI findings. They show that both the right temporal lobe and the parietal lobe play critical roles for voice-recognition abilities. The right temporal lobe might be key for the representation of the voice and speaker identity, while the parietal lobe might be involved in a more multimodal representation of person identities.