Yohana Lévêque

Impaired short-term memory for pitch in congenital amusia

Congenital amusia is a neuro-developmental disorder of music perception and production. The hypothesis is that the musical deficits arise from altered pitch processing, with impairments in pitch discrimination (i.e., pitch change detection, pitch direction discrimination and identification) and short-term memory. The present review article focuses on the deficit of short-term memory for pitch. Overall, the data discussed here suggest impairments at each level of processing in short-term memory tasks; starting with the encoding of the pitch information and the creation of the adequate memory trace, the retention of the pitch traces over time as well as the recollection and comparison of the stored information with newly incoming information. These impairments have been related to altered brain responses in a distributed fronto-temporal network, associated with decreased connectivity between these structures, as well as in abnormalities in the connectivity between the two auditory cortices. In contrast, amusic participants׳ short-term memory abilities for verbal material are preserved. These findings show that short-term memory deficits in congenital amusia are specific to pitch, suggesting a pitch-memory system that is, at least partly, separated from verbal memory. This article is part of a Special Issue entitled SI: Auditory working memory.

Altered intrinsic connectivity of the auditory cortex in congenital amusia

Congenital amusia, a neurodevelopmental disorder of music perception and production, has been associated with abnormal anatomical and functional connectivity in a right frontotemporal pathway. To investigate whether spontaneous connectivity in brain networks involving the auditory cortex is altered in the amusic brain, we ran a seed-based connectivity analysis, contrasting at-rest functional MRI data of amusic and matched control participants. Our results reveal reduced frontotemporal connectivity in amusia during resting state, as well as an overconnectivity between the auditory cortex and the default mode network (DMN). The findings suggest that the auditory cortex is intrinsically more engaged toward internal processes and less available to external stimuli in amusics compared with controls. Beyond amusia, our findings provide new evidence for the link between cognitive deficits in pathology and abnormalities in the connectivity between sensory areas and the DMN at rest.

Boosting pitch encoding with audiovisual interactions in congenital amusia

The combination of information across senses can enhance perception, as revealed for example by decreased reaction times or improved stimulus detection. Interestingly, these facilitatory effects have been shown to be maximal when responses to unisensory modalities are weak. The present study investigated whether audiovisual facilitation can be observed in congenital amusia, a music-specific disorder primarily ascribed to impairments of pitch processing. Amusic individuals and their matched controls performed two tasks. In Task 1, they were required to detect auditory, visual, or audiovisual stimuli as rapidly as possible. In Task 2, they were required to detect as accurately and as rapidly as possible a pitch change within an otherwise monotonic 5-tone sequence that was presented either only auditorily (A condition), or simultaneously with a temporally congruent, but otherwise uninformative visual stimulus (AV condition). Results of Task 1 showed that amusics exhibit typical auditory and visual detection, and typical audiovisual integration capacities: both amusics and controls exhibited shorter response times for audiovisual stimuli than for either auditory stimuli or visual stimuli. Results of Task 2 revealed that both groups benefited from simultaneous uninformative visual stimuli to detect pitch changes: accuracy was higher and response times shorter in the AV condition than in the A condition. The audiovisual improvements of response times were observed for different pitch interval sizes depending on the group. These results suggest that both typical listeners and amusic individuals can benefit from multisensory integration to improve their pitch processing abilities and that this benefit varies as a function of task difficulty. These findings constitute the first step towards the perspective to exploit multisensory paradigms to reduce pitch-related deficits in congenital amusia, notably by suggesting that audiovisual paradigms are effective in an appropriate range of unimodal performance.

Verbal and musical short-term memory: Variety of auditory disorders after stroke.

HighlightsStroke patients have auditory verbal and musical short‐term memory deficits.Inferior fronto‐parietal operculum is involved in auditory short‐term memory.Cerebral networks for verbal and musical memory are to some extent distinct. Abstract Auditory cognitive deficits after stroke may concern language and/or music processing, resulting in aphasia and/or amusia. The aim of the present study was to assess the potential deficits of auditory short‐term memory for verbal and musical material after stroke and their underlying cerebral correlates with a Voxel‐based Lesion Symptom Mapping approach (VLSM). Patients with an ischemic stroke in the right (N = 10) or left (N = 10) middle cerebral artery territory and matched control participants (N = 14) were tested with a detailed neuropsychological assessment including global cognitive functions, music perception and language tasks. All participants then performed verbal and musical auditory short‐term memory (STM) tasks that were implemented in the same way for both materials. Participants had to indicate whether series of four words or four tones presented in pairs, were the same or different. To detect domain‐general STM deficits, they also had to perform a visual STM task. Behavioral results showed that patients had lower performance for the STM tasks in comparison with control participants, regardless of the material (words, tones, visual) and the lesion side. The individual patient data showed a double dissociation between some patients exhibiting verbal deficits without musical deficits or the reverse. Exploratory VLSM analyses suggested that dorsal pathways are involved in verbal (phonetic), musical (melodic), and visual STM, while the ventral auditory pathway is involved in musical STM.

Amusie acquise et anhédonie musicale

Amusia is defined as an auditory agnosia, specifically related to music, resulting from a cerebral lesion or being of congenital origin. Amusia is rarely associated to musical anhedonia. We report the case of a 43-year-old patient who suffered in January 2012 from a right ischemic lesion affecting the superior temporal cortex, in particular lateral Heschl Gyrus and the posterior part of the Superior Temporal Gyrus (Brodmann areas 21 and 22). Neuropsychological tests revealed an amusia combined to musical anhedonia. The specificity of this case is based on the combination of both syndromes highlighting the relation between neural networks involved in the processing of musical information in both its perceptual and emotional components.

Boosting Maintenance in Working Memory with Temporal Regularities.

Music cognition research has provided evidence for the benefit of temporally regular structures guiding attention over time. The present study investigated whether maintenance in working memory can benefit from an isochronous rhythm. Participants were asked to remember series of 6 letters for serial recall. In the rhythm condition of Experiment 1A, a wood block sound was presented 6 times with a regular stimulus-onset-asynchrony during the delay between encoding and recall. In the silent condition, no sound was presented. The presence of the regular rhythm resulted in improved memory performance (Experiment 1A.), an effect also observed under articulatory suppression (Experiment 2), suggesting that temporal regularities can enhance maintenance in working memory including attentional refreshing. Experiment 1B confirmed this interpretation by showing that the presentation of a nonisochronous rhythm did not result in improved memory performance in comparison to a silent condition. The findings are discussed in relation to current working memory models and the theoretical framework of dynamic attending.

Musical emotions in congenital amusia: Impaired recognition, but preserved emotional intensity.

Objective: To further our understanding of the role of perceptual processes in musical emotions, we investigated individuals with congenital amusia, a neurodevelopmental disorder that alters pitch processing. Method: Amusic and matched control participants were studied for emotion recognition and emotion intensity ratings of both musical excerpts and faces. Results: Emotion recognition was found to be impaired in amusic participants relative to controls for the musical stimuli only. This impairment suggests that perceptual deficits in music processing reduce amusics’ access to a verbal and conscious representation of musical emotions. Nevertheless, amusics’ performance for emotion recognition was above chance level, and multidimensional scaling (MDS) analyses revealed that their categorization of musical pieces was based on similar representation spaces of emotions as for control participants. The emotion intensity ratings, nonverbal and possibly more implicit than the categorization task, seemed to be intact in amusic participants. Conclusions: These findings reveal that pitch deficits can hinder the recognition of emotions conveyed by musical pieces, while also highlighting the (at least partial) dissociation between emotion recognition and emotion intensity evaluation. Our study thus sheds light on the complex interactions between perceptual and emotional networks in the brain, by showing that impaired central auditory processing partially alters musical emotion processing.