Diminished large-scale functional brain networks in absolute pitch during the perception of naturalistic music and audiobooks.

Previous studies have reported the effects of absolute pitch (AP) and musical proficiency on the functioning of specific brain regions or distinct subnetworks, but they provided an incomplete account of the effects of AP and musical proficiency on whole-brain networks. In this study, we used EEG to estimate source-space whole-brain functional connectivity in a large sample comprising AP musicians (n â€‹= â€‹46), relative pitch (RP) musicians (n â€‹= â€‹45), and Non-musicians (n â€‹= â€‹34) during resting state, naturalistic music listening, and audiobook listening. First, we assessed the global network density of the participants' functional networks in these conditions. As revealed by cluster-based permutation testing, AP musicians showed a decreased mean degree compared to Non-musicians whereas RP musicians showed an intermediate mean degree not statistically different from Non-musicians or AP-musicians. This effect was present during naturalistic music and audiobook listening, but, crucially, not during resting state. Second, we identified the subnetworks that drove group differences in global network density using the network-based statistic approach. We found that AP musicians showed decreased functional connectivity between major hubs of the default mode network during both music and audiobook listening compared to Non-musicians. Third, we assessed group differences in global network topology while controlling for network density. We did not find evidence for group differences in the clustering coefficient and characteristic path length. Taken together, we found first evidence of diminished whole-brain functional networks in AP musicians during the perception of naturalistic auditory stimuli. These differences might reflect a complex interplay between AP ability, musical proficiency, music processing, and auditory processing per se.

Absolute and relative pitch processing in the human brain: neural and behavioral evidence.

Pitch is a primary perceptual dimension of sounds and is crucial in music and speech perception. When listening to melodies, most humans encode the relations between pitches into memory using an ability called relative pitch (RP). A small subpopulation, almost exclusively musicians, preferentially encode pitches using absolute pitch (AP): the ability to identify the pitch of a sound without an external reference. In this study, we recruited a large sample of musicians with AP (AP musicians) and without AP (RP musicians). The participants performed a pitch-processing task with a Listening and a Labeling condition during functional magnetic resonance imaging. General linear model analysis revealed that while labeling tones, AP musicians showed lower blood oxygenation level-dependent (BOLD) signal in the inferior frontal gyrus and the presupplementary motor area-brain regions associated with working memory, language functions, and auditory imagery. At the same time, AP musicians labeled tones more accurately suggesting that AP might be an example of neural efficiency. In addition, using multivariate pattern analysis, we found that BOLD signal patterns in the inferior frontal gyrus and the presupplementary motor area differentiated between the groups. These clusters were similar, but not identical compared to the general linear model-based clusters. Therefore, information about AP and RP might be present on different spatial scales. While listening to tones, AP musicians showed increased BOLD signal in the right planum temporale which may reflect the matching of pitch information with internal templates and corroborates the importance of the planum temporale in AP processing. Taken together, AP and RP musicians show diverging frontal activations during Labeling and, more subtly, differences in right auditory activation during Listening. The results of this study do not support the previously reported importance of the dorsolateral prefrontal cortex in associating a pitch with its label.

Emerging neural specialization of the ventral occipitotemporal cortex to characters through phonological association learning in preschool children.

The ventral occipitotemporal (vOT) cortex serves as a core region for visual processing, and specific areas of this region show preferential activation for various visual categories such as faces and print. The emergence of such functional specialization in the human cortex represents a pivotal developmental process, which provides a basis for targeted and efficient information processing. For example, functional specialization to print in the left vOT is an important prerequisite for fluent reading. However, it remains unclear, which processes initiate the preferential cortical activations to characters arising in the vOT during child development. Using a multimodal neuroimaging approach with preschool children at familial risk for developmental dyslexia, we demonstrate how varying levels of expertise modulate the neural response to single characters, which represent the building blocks of print units. The level of expertise to characters was manipulated firstly through brief training of false-font speech-sound associations and secondly by comparing characters for which children differed in their level of familiarity and expertise accumulated through abundant exposure in their everyday environment. Neural correlates of character processing were tracked with simultaneous high-density electroencephalography and functional magnetic resonance imaging in a target detection task. We found training performance and expertise-dependent modulation of the visual event-related potential around 220 ms (N1) and the corresponding vOT activation. Additionally, trained false-font characters revealed stronger functional connectivity between the left fusiform gyrus (FFG) seed and left superior parietal/lateral occipital cortex regions with higher training performance. In sum, our results demonstrate that learning artificial-character speech-sound associations enhances activation to trained characters in the vOT and that the magnitude of this activation and the functional connectivity of the left FFG to the parieto-occipital cortex depends on learning performance. This pattern of results suggests emerging development of the reading network after brief training that parallels network specialization during reading acquisition.

Univariate and multivariate analyses of functional networks in absolute pitch.

Absolute pitch (AP) refers to the rare ability to identify the pitch of any given tone without an external reference tone. Previous studies have shown that during auditory processing, AP musicians activate the auditory cortex (AC), the prefrontal cortex (PFC), and parietal areas of the brain. Therefore, it has been hypothesized that AP is sustained by a widespread functional network. In the present functional magnetic resonance imaging (fMRI) study, we tested this hypothesis by employing a mass-univariate analysis of resting-state functional connectivity within the AC, the PFC, and parietal areas in a large sample of musicians with and without AP (N = 100). AP musicians showed increased functional connectivity in the left middle frontal gyrus (MFG), left intraparietal sulcus (IPS), and right superior parietal lobule (SPL). These results provide the first evidence for an AP-specific network characterized by increased functional connections in higher-order cognitive areas. Interestingly, AP was not associated with increases in functional connectivity of the AC, but AP was successfully decoded from functional connectivity patterns in the left AC using multi-voxel pattern analysis (MVPA, also known as multivariate pattern analysis), with group classification accuracy being highest for the left Heschl's gyrus (HG). MVPA can capture fine-grained patterns in the brain connectivity profile of AP musicians, whilst a mass-univariate analysis is sensitive to macroscopic trends in the data. The successful differentiation of AP musicians by MVPA but not by a mass-univariate analysis of connectivity in the AC thus indicates that AP musicians differ in the fine-grained rather than the macroscopic AC function. Based on our findings, and in light of current literature, we propose pitch-label associations, tonal working memory, pitch categorization, and multimodal integration as potential mechanisms underlying the AP ability. This set of psychological functions is controlled by a distributed functional network and a particular AC connectivity pattern only present in AP musicians.

The Effect of Background Music on Inhibitory Functions: An ERP Study.

The influence of background music on cognitive functions is still a matter of debate. In this study, we investigated the influence of background music on executive functions (particularly on inhibitory functions). Participants completed a standardized cued Go/NoGo task during three different conditions while an EEG was recorded (1: with no background music, 2: with relaxing, or 3: with exciting background music). In addition, we collected reaction times, omissions, and commissions in response to the Go and NoGo stimuli. From the EEG data, event-related potentials (ERPs) were calculated for the Go and NoGo trials. From these ERPs, the N2 and P3 components were specifically analyzed since previous studies have shown that these components (and particularly the Go-NoGo difference waves) are strongly associated with inhibitory functions. The N2 and P3 components of the difference waves (N2d and P3d) were used for statistical analyses. The statistical analyses revealed no differences between the three conditions in terms of amplitudes and latencies of the N2d and P3d components. In addition, reaction times, omissions, and commissions were comparable across all conditions. Our results suggest that in the context of this paradigm, music as background acoustic stimulation has no detrimental effects on the performance of a Go/NoGo task and neural underpinnings.

Top-down signal transmission and global hyperconnectivity in auditory-visual synesthesia: Evidence from a functional EEG resting-state study.

Auditory-visual (AV) synesthesia is a rare phenomenon in which an auditory stimulus induces a "concurrent" color sensation. Current neurophysiological models of synesthesia mainly hypothesize "hyperconnected" and "hyperactivated" brains, but differ in the directionality of signal transmission. The two-stage model proposes bottom-up signal transmission from inducer- to concurrent- to higher-order brain areas, whereas the disinhibited feedback model postulates top-down signal transmission from inducer- to higher-order- to concurrent brain areas. To test the different models of synesthesia, we estimated local current density, directed and undirected connectivity patterns in the intracranial space during 2 min of resting-state (RS) EEG in 11 AV synesthetes and 11 nonsynesthetes. AV synesthetes demonstrated increased parietal theta, alpha, and lower beta current density compared to nonsynesthetes. Furthermore, AV synesthetes were characterized by increased top-down signal transmission from the superior parietal lobe to the left color processing area V4 in the upper beta frequency band. Analyses of undirected connectivity revealed a global, synesthesia-specific hyperconnectivity in the alpha frequency band. The involvement of the superior parietal lobe even during rest is a strong indicator for its key role in AV synesthesia. By demonstrating top-down signal transmission in AV synesthetes, we provide direct support for the disinhibited feedback model of synesthesia. Finally, we suggest that synesthesia is a consequence of global hyperconnectivity. Hum Brain Mapp 39:522-531, 2018. © 2017 Wiley Periodicals, Inc.