Listeners with congenital amusia are sensitive to context uncertainty in melodic sequences.

In typical listeners, the perceptual salience of a surprising auditory event depends on the uncertainty of its context. For example, in melodies, pitch deviants are more easily detected and generate larger neural responses when the context is highly predictable than when it is less so. However, it is not known whether amusic listeners with abnormal pitch processing are sensitive to the degree of uncertainty of pitch sequences and, if so, whether they are to a different extent than typical non-musician listeners. To answer this question, we manipulated the uncertainty of short melodies while participants with and without congenital amusia underwent EEG recordings in a passive listening task. Uncertainty was manipulated by presenting melodies with different levels of complexity and familiarity, under the assumption that simpler and more familiar patterns would enhance pitch predictability. We recorded mismatch negativity (MMN) responses to pitch, intensity, timbre, location, and rhythm deviants as a measure of auditory surprise. In both participant groups, we observed reduced MMN amplitudes and longer peak latencies for all sound features with increasing levels of complexity, and putative familiarity effects only for intensity deviants. No significant group-by-complexity or group-by-familiarity interactions were detected. However, in contrast to previous studies, pitch MMN responses in amusics were disrupted in high complexity and unfamiliar melodies. The present results thus indicate that amusics are sensitive to the uncertainty of melodic sequences and that preattentive auditory change detection is greatly spared in this population across sound features and levels of predictability. However, our findings also hint at pitch-specific impairments in this population when uncertainty is high, thus suggesting that pitch processing under high uncertainty conditions requires an intact frontotemporal loop.

Self-perceived attention difficulties are associated with sensory hypersensitivity in migraine.

BACKGROUND: Attention is the process which enables to preferentially select salient or relevant stimuli and to attenuate the response to irrelevant incoming stimuli. Migraine is characterized by both attentional alterations and an abnormal sensory processing to external stimulations. The aim of the study was to investigate potential interactions between self-perceived attentional difficulties and sensory hypersensitivity in migraine patients. METHODS: Forty-six episodic migraineurs without aura and 46 healthy controls filled out questionnaires on self-perceived attention difficulties and self-reported sensitivity to visual, auditory and olfactory stimulations. RESULTS: Compared to controls, migraineurs reported significantly higher levels of attention difficulty and sensory sensitivity. Sensory hypersensitivity correlated significantly with self-perceived attentional difficulties in migraineurs (P=0.002), but not with migraine disability or levels of anxiety or depression. Ictal and interictal sensory sensitivities were significantly correlated in migraineurs within visual (P<0.001), auditory (P<0.001) and olfactory (P=0.001) modalities. CONCLUSION: This study shows for the first time an association between self-reported attentional difficulties and multimodal sensory hypersensitivity. Studies combining behavioral and physiological measures of sensory processing and attention processes are necessary to further understand the peculiar vulnerability of migraineurs to sensory stimuli.

Emotional prosody in congenital amusia: Impaired and spared processes.

Congenital amusia is a lifelong deficit of music processing, in particular of pitch processing. Most research investigating this neurodevelopmental disorder has focused on music perception, but pitch also has a critical role for intentional and emotional prosody in speech. Two previous studies investigating amusics' emotional prosody recognition have shown either some deficit or no deficit (compared to controls). However, these previous studies have used only long sentence stimuli, which allow for limited control over acoustic content. Here, we tested amusic individuals for emotional prosody perception in sentences and vowels. For each type of material, participants performed an emotion categorization task, followed by intensity ratings of the recognized emotion. Compared to controls, amusic individuals had similar recognition of emotion in sentences, but poorer performance in vowels, especially when distinguishing sad and neutral stimuli. These lower performances in amusics were linked with difficulties in processing pitch and spectro-temporal parameters of the vowel stimuli. For emotion intensity, neither sentence nor vowel ratings differed between participant groups, suggesting preserved implicit processing of emotional prosody in amusia. These findings can be integrated into previous data showing preserved implicit processing of pitch and emotion in amusia alongside deficits in explicit recognition tasks. They are thus further supporting the hypothesis of impaired conscious analysis of pitch and timbre in this neurodevelopmental disorder.

Differential effects of non-dual and focused attention meditations on the formation of automatic perceptual habits in expert practitioners.

Non-dual meditation aims to undo maladaptive cognitive and affective patterns by recognizing their constructed and transient nature. We previously found high-amplitude spontaneous gamma (25-40 Hz) oscillatory activity during such practice. Nonetheless, it is unclear how this meditation state differs from other practices, in terms of perceptual information processing. Here, we hypothesized that non-dual meditation can downregulate the automatic formation of perceptual habits. To investigate this hypothesis, we recorded EEG from expert Buddhist meditation practitioners and matched novices to measure two components of the auditory evoked response: the Mismatch Negativity (MMN) and the Late Frontal Negativity (LFN), a potential observed at a latency sensitive to attentional engagement to the auditory environment, during the practices of Open Presence (OP) and Focused Attention (FA), as well as during a control state, in the context of a passive oddball paradigm. We found an increase in gamma oscillatory power during both meditation states in expert practitioners and an interaction between states and groups in the amplitude of the MMN. A further investigation identified the specific interplay between the MMN and the LFN as a possible marker to differentiate the two meditation states as a function of expertise. In experts, the MMN increased during FA, compared to OP, while the opposite pattern was observed at the LFN latency. We propose that the state of OP in experts is characterized by increased sensory monitoring and reduced perceptual inferences compared to FA. This study represents a first attempt to describe the impact of non-dual meditation states on the regulation of automatic brain predictive processes.

Congenital amusias.

In contrast to the sophisticated music processing reported in the general population, individuals with congenital amusia show deficits in music perception and production. Congenital amusia occurs without brain damage, sensory or cognitive deficits, and has been suggested as a lifelong deficit with genetic origin. Even though recognized for a long time, this disorder has been systematically studied only relatively recently for its behavioral and neural correlates. The currently most investigated hypothesis about the underlying deficits concerns the pitch dimension, notably with impaired pitch discrimination and memory. Anatomic and functional investigations of pitch processing revealed that the amusic brain presents abnormalities in the auditory and inferior frontal cortices, associated with decreased connectivity between these structures. The deficit also impairs processing of pitch in speech material and processing of the time dimension in music for some of the amusic individuals, but does not seem to affect spatial processing. Some studies suggest at least partial dissociation in the disorder between perception and production. Recent studies revealed spared implicit pitch perception in congenital amusia, supporting the power of implicit cognition in the music domain. Current challenges consist in defining different subtypes of congenital amusia as well as developing rehabilitation programs for this "musical handicap."

[Acquired amusia and musical anhedonia]. / 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.

[Neurophysiological evaluation of cortical excitability in migraine: a review of the literature]. / Évaluation électrophysiologique de l'excitabilité corticale dans la migraine.

INTRODUCTION: Neurophysiological studies point to altered cortical neuronal excitability in migraine patients. STATE OF ART: Between attacks, migraine brain seems to be "hyperresponsive" to repetitive stimuli, as suggested by evoked potential studies that show a lack of habituation to sensory stimuli. Transcranial magnetic stimulation suggests an impairment of intracortical inhibitory circuits in migraine, especially in migraine with aura. Controversial results are obtained in migraineurs without aura. Repetitive transcranial magnetic stimulation also shows in migraine with aura a paradoxical enhancement of intracortical facilitation by low frequency stimulation and greater increased facilitatory mechanisms by high-frequency stimulation. Importantly, cortical excitability level fluctuates over time in relation to the migraine cycle. The interictal lack of habituation to sensory stimuli normalizes before and during a migraine attack. Changes of cortical excitability consistent with the theory of cortical spreading depression are also observed during migraine aura with magnetoencephalography. PERSPECTIVES: The exact role of cortical excitability changes in migraine pathophysiology and possibly in chronic migraine is still unknown. Further studies are also necessary to clarify the role of migraine preventive drugs on brain excitability. CONCLUSIONS: In this review, the results of neurophysiological studies conducted in migraine patients will be described and the associated pathophysiological hypotheses will be discussed.

Schizophrenia and frontal cortex: where does it fail?

Schizophrenia is characterized by cognitive, social, and emotional impairments and by psychotic symptoms. Neuroimaging studies have reported abnormalities within the prefrontal cortex and it has been hypothesized that schizophrenia results from poor or miswired anatomical/functional connections. We have compared the functional connectivity within the frontal cortex in control and schizophrenic subjects during the realization of a Continuous Performance Task. The connectivity pattern within the frontal cortex was uncovered by the analysis of the correlation matrix computed from the fMRI time series in frontal areas for 14 schizophrenic patients and 14 control subjects. In control subjects, the right dorsolateral prefrontal cortex (DLFCr) activity correlated i) positively with the left dorsolateral prefrontal cortex and the posterior part of the supplementary motor area, ii) negatively with the medial and anterior/inferior part of the frontal cortex. In the schizophrenic group, these relations were abolished or strongly lowered. The negative relation between the DLFCr and the medial frontal cortex has been proposed to play a key role in setting a harmonious balance between the direction of attention to the external world and the expression of the individual believes and self-referential activities, and therefore, the impaired relation of right DLFCr with other frontal areas could explain a distorted perception of external world in relation with internal motivations.

Cerebral gray and white matter reductions and clinical correlates in patients with early onset schizophrenia.

Few magnetic resonance imaging studies of schizophrenia have investigated brain tissue volumes and their relation to clinical symptoms in patients with an early age at illness onset. The twofold purpose of the study was to investigate both gray and white matter volumes in schizophrenic men with an early age at illness onset, and to determine whether clinical features correlated with tissue volume changes, using an automated voxel-by-voxel image analysis procedure. Twenty male patients with DSM-IV diagnoses of schizophrenia, and an early age at onset (m+/-SD=19+/-2) were compared with 20 age-matched health men. Magnetic resonance (1.5-T) scans were obtained with an Inversion-Recovery prepared fast gradient echo sequence enhancing gray and white matter contrast. Statistical Parametric Mapping was used for image segmentation and comparison. Patients had significant gray matter reductions in medial frontal gyri, left insula, left parahippocampus, and left fusiform gyrus; bilateral white matter reductions in frontal lobes, and increased total cerebrospinal fluid volume were also observed. Negative symptom scores were negatively related to white matter volumes in cingulate regions, and in the right internal capsule. These findings emphasize a pattern of left-hemisphere gray matter abnormalities, and suggest that fronto-paralimbic connectivity may be altered in men with early onset schizophrenia.