Investigating the different mechanisms in related neural activities: a focus on auditory perception and imagery.

Neuroimaging studies have shown that the neural representation of imagery is closely related to the perception modality; however, the undeniable different experiences between perception and imagery indicate that there are obvious neural mechanism differences between them, which cannot be explained by the simple theory that imagery is a form of weak perception. Considering the importance of functional integration of brain regions in neural activities, we conducted correlation analysis of neural activity in brain regions jointly activated by auditory imagery and perception, and then brain functional connectivity (FC) networks were obtained with a consistent structure. However, the connection values between the areas in the superior temporal gyrus and the right precentral cortex were significantly higher in auditory perception than in the imagery modality. In addition, the modality decoding based on FC patterns showed that the FC network of auditory imagery and perception can be significantly distinguishable. Subsequently, voxel-level FC analysis further verified the distribution regions of voxels with significant connectivity differences between the 2 modalities. This study complemented the correlation and difference between auditory imagery and perception in terms of brain information interaction, and it provided a new perspective for investigating the neural mechanisms of different modal information representations.

Sensorimotor Synchronization and Neural Entrainment to Imagined Rhythms in Individuals With Proficient Imagery Ability.

Sensorimotor synchronization (SMS) is the temporal coordination of motor movements with external or imagined stimuli. Finger-tapping studies indicate better SMS performance with auditory or tactile stimuli compared to visual. However, SMS with a visual rhythm can be improved by enriching stimulus properties (e.g., spatiotemporal content) or individual differences (e.g., one's vividness of auditory imagery). We previously showed that higher self-reported vividness of auditory imagery led to more consistent synchronization-continuation performance when participants continued without a guiding visual rhythm. Here, we examined the contribution of imagery to the SMS performance of proficient imagers, including an auditory or visual distractor task during the continuation phase. While the visual distractor task had minimal effect, SMS consistency was significantly worse when the auditory distractor task was present. Our electroencephalography analysis revealed beat-related neural entrainment, only when the visual or auditory distractor tasks were present. During continuation with the auditory distractor task, the neural entrainment showed an occipital electrode distribution, suggesting the involvement of visual imagery. Unique to SMS continuation with the auditory distractor task, we found neural and sub-vocal (measured with electromyography) entrainment at the three-beat pattern frequency. In this most difficult condition, proficient imagers employed both beat- and pattern-related imagery strategies. However, this combination was insufficient to restore SMS consistency to that observed with visual or no distractor task. Our results suggest that proficient imagers effectively utilized beat-related imagery in one modality when imagery in another modality was limited.

Mapping Specific Mental Content during Musical Imagery.

Humans can mentally represent auditory information without an external stimulus, but the specificity of these internal representations remains unclear. Here, we asked how similar the temporally unfolding neural representations of imagined music are compared to those during the original perceived experience. We also tested whether rhythmic motion can influence the neural representation of music during imagery as during perception. Participants first memorized six 1-min-long instrumental musical pieces with high accuracy. Functional MRI data were collected during: 1) silent imagery of melodies to the beat of a visual metronome; 2) same but while tapping to the beat; and 3) passive listening. During imagery, inter-subject correlation analysis showed that melody-specific temporal response patterns were reinstated in right associative auditory cortices. When tapping accompanied imagery, the melody-specific neural patterns were reinstated in more extensive temporal-lobe regions bilaterally. These results indicate that the specific contents of conscious experience are encoded similarly during imagery and perception in the dynamic activity of auditory cortices. Furthermore, rhythmic motion can enhance the reinstatement of neural patterns associated with the experience of complex sounds, in keeping with models of motor to sensory influences in auditory processing.

Common cortical areas involved in both auditory and visual imageries for novel stimuli.

We examine cross-modality commonalities in visual and auditory imageries during fMRI scanning in a sample of healthy young adults. In a visual task combining viewed and imagined stimuli, 28 participants were asked to imagine novel scenes related to the other images, and in a similar auditory task combining heard and imagined stimuli, to imagine novel sentences spoken by individuals they had heard speaking previously. We identified a common set of regions in medial and lateral Brodmann area 6, as well as inferior frontal gyrus (BA 44/45), partially supporting previous meta-analytic results. Comparing individuals with high or low reported imagery ability, we replicated a previous result showing individuals with lower visual imagery ability showed greater activation in the cerebellum, frontal and dorsolateral prefrontal cortex, while there was no relationship with auditory imagery ability in this sample. The emphasis on imagining novel stimuli, rather than familiar or previously experienced stimuli, confirms the role of the supramodal imagery network underlying creative imagery.

Dissociation of Neural Networks for Predisposition and for Training-Related Plasticity in Auditory-Motor Learning.

Skill learning results in changes to brain function, but at the same time individuals strongly differ in their abilities to learn specific skills. Using a 6-week piano-training protocol and pre- and post-fMRI of melody perception and imagery in adults, we dissociate learning-related patterns of neural activity from pre-training activity that predicts learning rates. Fronto-parietal and cerebellar areas related to storage of newly learned auditory-motor associations increased their response following training; in contrast, pre-training activity in areas related to stimulus encoding and motor control, including right auditory cortex, hippocampus, and caudate nuclei, was predictive of subsequent learning rate. We discuss the implications of these results for models of perceptual and of motor learning. These findings highlight the importance of considering individual predisposition in plasticity research and applications.

Feel the Noise: Relating Individual Differences in Auditory Imagery to the Structure and Function of Sensorimotor Systems.

Humans can generate mental auditory images of voices or songs, sometimes perceiving them almost as vividly as perceptual experiences. The functional networks supporting auditory imagery have been described, but less is known about the systems associated with interindividual differences in auditory imagery. Combining voxel-based morphometry and fMRI, we examined the structural basis of interindividual differences in how auditory images are subjectively perceived, and explored associations between auditory imagery, sensory-based processing, and visual imagery. Vividness of auditory imagery correlated with gray matter volume in the supplementary motor area (SMA), parietal cortex, medial superior frontal gyrus, and middle frontal gyrus. An analysis of functional responses to different types of human vocalizations revealed that the SMA and parietal sites that predict imagery are also modulated by sound type. Using representational similarity analysis, we found that higher representational specificity of heard sounds in SMA predicts vividness of imagery, indicating a mechanistic link between sensory- and imagery-based processing in sensorimotor cortex. Vividness of imagery in the visual domain also correlated with SMA structure, and with auditory imagery scores. Altogether, these findings provide evidence for a signature of imagery in brain structure, and highlight a common role of perceptual-motor interactions for processing heard and internally generated auditory information.

Beyond visual imagery: how modality-specific is enhanced mental imagery in synesthesia?

Synesthesia based in visual modalities has been associated with reports of vivid visual imagery. We extend this finding to consider whether other forms of synesthesia are also associated with enhanced imagery, and whether this enhancement reflects the modality of synesthesia. We used self-report imagery measures across multiple sensory modalities, comparing synesthetes' responses (with a variety of forms of synesthesia) to those of non-synesthete matched controls. Synesthetes reported higher levels of visual, auditory, gustatory, olfactory and tactile imagery and a greater level of imagery use. Furthermore, their reported enhanced imagery is restricted to the modalities involved in the individual's synesthesia. There was also a relationship between the number of forms of synesthesia an individual has, and the reported vividness of their imagery, highlighting the need for future research to consider the impact of multiple forms of synesthesia. We also recommend the use of behavioral measures to validate these self-report findings.

Multisensory approach in Mental Imagery: ALE meta-analyses comparing Motor, Visual and Auditory Imagery.

Mental Imagery is a topic of longstanding and widespread scientific interest. Individual studies have typically focused on a single modality (e.g. Motor, Visual, Auditory) of Mental Imagery. Relatively little work has considered directly comparing and contrasting the brain networks associated with these different modalities of Imagery. The present study integrates data from 439 neuroimaging experiments to identify both modality-specific and shared neural networks involved in Mental Imagery. Comparing the networks involved in Motor, Visual, and Auditory Imagery identified a pattern whereby each form of Imagery preferentially recruited 'higher level' associative brain regions involved in the associated 'real' experience. Results also indicate significant overlap in a left-lateralized network including the pre-supplementary motor area, ventral premotor cortex and inferior parietal lobule. This pattern of results supports the existence of a 'core' network that supports the attentional, spatial, and decision-making demands of Mental Imagery. Together these results offer new insights into the brain networks underlying human imagination.

Absolute pitch in involuntary musical imagery.

Memory for isolated absolute pitches is extremely rare in Western, English-speaking populations. However, past research has found that people can voluntarily reproduce well-known songs in the original key much more often than chance. It is unknown whether this requires deliberate effort or if it manifests in involuntary musical imagery (INMI, or earworms). Participants (N = 30, convenience sample) were surveyed at random times over a week and asked to produce a sung recording of any music they were experiencing in their heads. We measured the "pitch error" of each recording to the nearest semitone by comparing participants' recordings to the original song. We found that 44.7% of recordings had a pitch error of 0 semitones, and 68.9% of recordings were within ± 1 semitone of the original song. Our results provide novel evidence that a large proportion of the population has access to absolute pitch, as revealed in their INMI.

Attention Control and Audiomotor Processes Underlying Anticipation of Musical Themes while Listening to Familiar Sonata-Form Pieces.

When listening to music, people are excited by the musical cues immediately before rewarding passages. More generally, listeners attend to the antecedent cues of a salient musical event irrespective of its emotional valence. The present study used functional magnetic resonance imaging to investigate the behavioral and cognitive mechanisms underlying the cued anticipation of the main theme's recurrence in sonata form. Half of the main themes in the musical stimuli were of a joyful character, half a tragic character. Activity in the premotor cortex suggests that around the main theme's recurrence, the participants tended to covertly hum along with music. The anterior thalamus, pre-supplementary motor area (preSMA), posterior cerebellum, inferior frontal junction (IFJ), and auditory cortex showed increased activity for the antecedent cues of the themes, relative to the middle-last part of the themes. Increased activity in the anterior thalamus may reflect its role in guiding attention towards stimuli that reliably predict important outcomes. The preSMA and posterior cerebellum may support sequence processing, fine-grained auditory imagery, and fine adjustments to humming according to auditory inputs. The IFJ might orchestrate the attention allocation to motor simulation and goal-driven attention. These findings highlight the attention control and audiomotor components of musical anticipation.

Composing in the scanner: A functional magnetic resonance imaging single case study on visual and auditory imagery.

"Seeing with the mind's eye" and "hearing with the mind's ear" are two common indicators of musical imagery, and they can be referred to as "visual" and "auditory" musical imagery. However, a question remains open, that is, whether visual and auditory imagery of the same musical composition share the same neural mechanisms. Moreover, how can neural mechanisms guarantee the temporal flow of "musical imagery"? To answer these questions, we report here a preliminary single case study using functional magnetic resonance imaging with an eminent composer who imagined one of his compositions in two states of mind as compared to his resting-state activity. In the visual imagery condition, he imagined visually the score of his composition in a continuous way. In the auditory imagery condition, he imagined auditorily the same musical composition with pauses. In spite of the modality and temporal differences, the two types of mental imagery showed similar temporal durations for the same musical composition. However, different patterns of neural activation were observed for visual and auditory imagery with one important exception, that is, a common activation pattern was observed in the left medial temporal gyrus in both visual and auditory imagery. We speculate that the left medial temporal gyrus may play an important role in the creation of apparent temporal continuity in musical imagery and perhaps even in conscious information processing in general.

Anauralia: The Silent Mind and Its Association With Aphantasia.

Auditory and visual imagery were studied in a sample of 128 participants, including 34 self-reported aphantasics. Auditory imagery (Bucknell Auditory Imagery Scale-Vividness, BAIS-V) and visual imagery (Vividness of Visual Imagery Questionnaire-Modified, VVIQ-M) were strongly associated, Spearman's rho = 0.83: Most self-reported aphantasics also reported weak or entirely absent auditory imagery; and participants lacking auditory imagery tended to be aphantasic. Similarly, vivid visual imagery tended to co-occur with vivid auditory imagery. Nevertheless, the aphantasic group included one individual with typical auditory imagery; and the group lacking auditory imagery (N = 29) included one individual with typical visual imagery. Hence, weak visual and auditory imagery can dissociate, albeit with low apparent incidence. Auditory representations and auditory imagery are thought to play a key role in a wide range of psychological domains, including working memory and memory rehearsal, prospective cognition, thinking, reading, planning, problem-solving, self-regulation, and music. Therefore, self-reports describing an absence of auditory imagery raise a host of important questions concerning the role of phenomenal auditory imagery in these domains. Because there is currently no English word denoting an absence of auditory imagery, we propose a new term, anauralia, for referring to this, and offer suggestions for further research.

Imagine, Sing, Play- Combined Mental, Vocal and Physical Practice Improves Musical Performance.

Classical musicians face a high demand for flawless and expressive performance, leading to highly intensified practice activity. Whereas the advantage of using mental strategies is well documented in sports research, few studies have explored the efficacy of mental imagery and overt singing on musical instrumental learning. In this study, 50 classically trained trumpet students performed short unfamiliar pieces. Performances were recorded before and after applying four prescribed practice strategies which were (1) physical practice, (2) mental imagery, (3) overt singing with optional use of solfege, (4) a combination of 1, 2 and 3 or a control condition, no practice. Three experts independently assessed pitch and rhythm accuracy, sound quality, intonation, and musical expression in all recordings. We found higher gains in the overall performance, as well as in pitch accuracy for the physical practice, and the combined practice strategies, compared to no practice. Furthermore, only the combined strategy yielded a significant improvement in musical expression. Pitch performance improvement was positively correlated with previous solfege training and frequent use of random practice strategies. The findings highlight benefits from applying practice strategies that complement physical practice in music instrument practice in short term early stages of learning a new piece. The study may generalize to other forms of learning, involving cognitive processes and motor skills.

An Exploratory Study of Imagining Sounds and "Hearing" Music in Autism.

Individuals with autism spectrum disorder (ASD) reportedly possess preserved or superior music-processing skills compared to their typically developing counterparts. We examined auditory imagery and earworms (tunes that get "stuck" in the head) in adults with ASD and controls. Both groups completed a short earworm questionnaire together with the Bucknell Auditory Imagery Scale. Results showed poorer auditory imagery in the ASD group for all types of auditory imagery. However, the ASD group did not report fewer earworms than matched controls. These data suggest a possible basis in poor auditory imagery for poor prosody in ASD, but also highlight a separability between auditory imagery and control of musical memories. The separability is present in the ASD group but not in typically developing individuals.

Do patients with hallucinations imagine speech right?

A direct relationship between auditory verbal hallucinations (AVHs) and decreased left-hemispheric lateralization in speech perception has been often described, although it has not been conclusively proven. The specific lateralization of AVHs has been poorly explored. However, patients with verbal hallucinations show a weak Right Ear Advantage (REA) in verbal perception compared to non AVHs listeners suggesting that left-hemispheric language area are involved in AVHs. In the present study, 29 schizophrenia patients with AVHs, 31 patients with psychotic bipolar disorder who experienced frequent AVHs, 27 patients with schizophrenia who had never experienced AVHs and 57 healthy controls were required to imagine hearing a voice in one ear alone. In line with previous evidence healthy controls confirmed the expected REA for auditory imagery, and the same REA was also found in non-hallucinator patients. However, in line with our hypothesis, patients with schizophrenia and psychotic bipolar disorder with AVHs showed no lateral bias. Results extend the relationship between abnormal asymmetry for verbal stimuli and AVHs to verbal imagery, suggesting that atypical verbal imagery may reflect a disruption of inter-hemispheric connectivity between areas implicated in the generation and monitoring of verbal imagery and may be predictive of a predisposition for AVHs. Results also indicate that the relationship between AVHs and hemispheric lateralization for auditory verbal imagery is not specific to schizophrenia but may extend to other disorders as well.

ERP data on auditory imagery of native and non-native English speech during silent reading.

This article presents the data analyzed in the paper "Is imagining a voice like listening to it? Evidence from ERPs" [1]. The data include individual ERP data when participants were performing auditory imagery of native and non-native English speech during silent reading vs. normal silent reading, and behavioral results from participants performing the Nelson-Denny Reading Comprehension task and Bucknell Auditory Imagery Scale (BAIS). The repository includes the R scripts used to carry out the statistical analyses reported in the original paper.

An investigation of the neural association between auditory imagery and perception of complex sounds.

Neuroimaging studies have demonstrated that mental imagery and perception share similar neural substrates, however, there are still ambiguities according to different auditory imagery content. In addition, there is still a lack of information regarding the underlying neural correlation between the two modalities. In the present study, we adopted functional magnetic resonance imaging to explore the neural representation during imagery and perception of actual sounds in our surroundings. Univariate analysis was used to assess the differences between the modalities of average activation intensity, and stronger imagery activation was found in sensorimotor regions but weaker activation in auditory association cortices. Additionally, multi-voxel pattern analysis with a support vector machine classifier was implemented to decode environmental sounds within- or cross-modality. Significant above-chance accuracies were found in all overlapping regions in the classification of within-modality, while successful cross-modality classification only was found in sensorimotor regions. Both univariate and multivariate analyses found distinct representation between auditory imagery and perception in the overlapping regions, including superior temporal gyrus and inferior frontal sulcus as well as the precentral cortex and pre-supplementary motor area. Our results confirm the overlapping activation regions between auditory imagery and perception reported by previous studies and suggest that activation regions showed dissociable representation pattern in imagery and perception of sound categories.

Pitch-specific contributions of auditory imagery and auditory memory in vocal pitch imitation.

Vocal imitation guides both music and language development. Despite the developmental significance of this behavior, a sizable minority of individuals are inaccurate at vocal pitch imitation. Although previous research suggested that inaccurate pitch imitation results from deficient sensorimotor associations between pitch perception and vocal motor planning, the cognitive processes involved in sensorimotor translation are not clearly defined. In the present research, we investigated the roles of basic cognitive processes in the vocal imitation of pitch, as well as the degree to which these processes rely on pitch-specific resources. In the present study, participants completed a battery of pitch and verbal tasks to measure pitch perception, pitch and verbal auditory imagery, pitch and verbal auditory short-term memory, and pitch imitation ability. Information on participants' music background was collected, as well. Pitch imagery, pitch short-term memory, pitch discrimination ability, and musical experience were unique predictors of pitch imitation ability. Furthermore, pitch imagery was a partial mediator of the relationship between pitch short-term memory and pitch imitation ability. These results indicate that vocal imitation recruits cognitive processes that rely on at least partially separate neural resources for pitch and verbal representations.

Mental Control in Musical Imagery: A Dual Component Model.

Hearing music in your head is a ubiquitous experience, but the role mental control plays in these experiences has not been deeply addressed. In this conceptual analysis, a dual-component model of mental control in musical imagery experiences is developed and discussed. The first component, initiation, refers to whether the musical imagery experience began voluntarily or involuntarily. The second component, management, refers to instances of control that occur after the experience has begun (e.g., changing the song, stopping the experience). Given the complex nature of this inner experience, we propose a new model combining and integrating four literatures: lab-based auditory imagery research using musical stimuli; involuntary musical imagery; mental rehearsal and composition in musicians; and in vivo studies of musical imagery in everyday environments. These literatures support the contention that mental control of musical imagery is multi-faceted. Future research should investigate these two components of mental control and better integrate the diverse literatures on musical imagery.

Covert singing in anticipatory auditory imagery.

To date, several fMRI studies reveal activation in motor planning areas during musical auditory imagery. We addressed whether such activations may give rise to peripheral motor activity, termed subvocalization or covert singing, using surface electromyography. Sensors placed on extrinsic laryngeal muscles, facial muscles, and a control site on the bicep measured muscle activity during auditory imagery that preceded singing, as well as during the completion of a visual imagery task. Greater activation was found in laryngeal and lip muscles for auditory than for visual imagery tasks, whereas no differences across tasks were found for other sensors. Furthermore, less accurate singers exhibited greater laryngeal activity during auditory imagery than did more accurate singers. This suggests that subvocalization may be used as a strategy to facilitate auditory imagery, which appears to be degraded in inaccurate singers. Taken together, these results suggest that subvocalization may play a role in anticipatory auditory imagery, and possibly as a way of supplementing motor associations with auditory imagery.