Giacomo Novembre

What can music tell us about social interaction

Humans are innately social creatures, but cognitive neuroscience, that has traditionally focused on individual brains, is only now beginning to investigate social cognition through realistic interpersonal interaction. Music provides an ideal domain for doing so because it offers a promising solution for balancing the trade-off between ecological validity and experimental control when testing cognitive and brain functions. Musical ensembles constitute a microcosm that provides a platform for parametrically modeling the complexity of human social interaction.

A conceptual review on action-perception coupling in the musicians' brain: what is it good for?

Experience with a sensorimotor task, such as practicing a piano piece, leads to strong coupling of sensory (visual or auditory) and motor cortices. Here we review behavioral and neurophysiological (M/EEG, TMS and fMRI) research exploring this topic using the brain of musicians as a model system. Our review focuses on a recent body of evidence suggesting that this form of coupling might have (at least) two cognitive functions. First, it leads to the generation of equivalent predictions (concerning both when and what event is more likely to occur) during both perception and production of music. Second, it underpins the common coding of perception and action that supports the integration of the motor output of multiple musicians’ in the context of joint musical tasks. Essentially, training-based coupling of perception and action might scaffold the human ability to represent complex (structured) actions and to entrain multiple agents—via reciprocal prediction and adaptation—in the pursuit of shared goals.

A grammar of action generates predictions in skilled musicians

The present study investigates shared representations of syntactic knowledge in music and action. We examined whether expectancy violations in musical harmonic sequences are also perceived as violations of the movement sequences necessary to produce them. Pianists imitated silent videos showing one hand playing chord sequences on a muted keyboard. Results indicate that, despite the absence of auditory feedback, imitation of a chord is fastest when it is congruent with the preceding harmonic context. This suggests that the harmonic rules implied by observed actions induce expectations that influence action execution. As evidence that these predictions are derived at a high representational level, imitation was more accurate for harmonically incongruent chords than for congruent chords executed with unconventional fingering. The magnitude of the effects of context and goal prioritization increased with musical training. Thus, musical training may lead to a domain-general representation of musical grammar, i.e., to a grammar of action.

Interpersonal synchrony enhanced through 20 Hz phase-coupled dual brain stimulation

Synchronous movement is a key component of social behaviour in several species including humans. Recent theories have suggested a link between interpersonal synchrony of brain oscillations and interpersonal movement synchrony. The present study investigated this link. Using transcranial alternating current stimulation (tACS) applied over the left motor cortex, we induced beta band (20 Hz) oscillations in pairs of individuals who both performed a finger-tapping task with the right hand. In-phase or anti-phase oscillations were delivered during a preparatory period prior to movement and while the tapping task was performed. In-phase 20 Hz stimulation enhanced interpersonal movement synchrony, compared to anti-phase or sham stimulation, particularly for the initial taps following the preparatory period. This was confirmed in an analysis comparing real vs. pseudo pair surrogate data. No enhancement was observed for stimulation frequencies of 2 Hz (matching the target movement frequency) or 10 Hz (alpha band). Thus, phase-coupling of beta band neural oscillations across two individuals’ (resting) motor cortices supports the interpersonal alignment of sensorimotor processes that regulate rhythmic action initiation, thereby facilitating the establishment of synchronous movement. Phaselocked dual brain stimulation provides a promising method to study causal effects of interpersonal brain synchrony on social, sensorimotor and cognitive processes.Abstract Synchronous movement is a key component of social behavior in several species including humans. Recent theories have suggested a link between interpersonal synchrony of brain oscillations and interpersonal movement synchrony. The present study investigated this link. Using transcranial alternating current stimulation (tACS) applied over the left motor cortex, we induced beta band (20 Hz) oscillations in pairs of individuals who both performed a finger-tapping task with the right hand. In-phase or anti-phase oscillations were delivered during a preparatory period prior to movement and while the tapping task was performed. In-phase 20 Hz stimulation enhanced interpersonal movement synchrony, compared with anti-phase or sham stimulation, particularly for the initial taps following the preparatory period. This was confirmed in an analysis comparing real vs pseudo pair surrogate data. No enhancement was observed for stimulation frequencies of 2 Hz (matching the target movement frequency) or 10 Hz (alpha band). Thus, phase-coupling of beta band neural oscillations across two individuals’ (resting) motor cortices supports the interpersonal alignment of sensorimotor processes that regulate rhythmic action initiation, thereby facilitating the establishment of synchronous movement. Phase-locked dual brain stimulation provides a promising method to study causal effects of interpersonal brain synchrony on social, sensorimotor and cognitive processes.

Neural alpha oscillations index the balance between self-other integration and segregation in real-time joint action

Shared knowledge and interpersonal coordination are prerequisites for most forms of social behavior. Influential approaches to joint action have conceptualized these capacities in relation to the separate constructs of co-representation (knowledge) and self-other entrainment (coordination). Here we investigated how brain mechanisms involved in co-representation and entrainment interact to support joint action. To do so, we used a musical joint action paradigm to show that the neural mechanisms underlying co-representation and self-other entrainment are linked via a process - indexed by EEG alpha oscillations - regulating the balance between self-other integration and segregation in real time. Pairs of pianists performed short musical items while action familiarity and interpersonal (behavioral) synchronization accuracy were manipulated in a factorial design. Action familiarity referred to whether or not pianists had rehearsed the musical material performed by the other beforehand. Interpersonal synchronization was manipulated via congruent or incongruent tempo change instructions that biased performance timing towards the impending, new tempo. It was observed that, when pianists were familiar with each others parts, millisecond variations in interpersonal synchronized behavior were associated with a modulation of alpha power over right centro-parietal scalp regions. Specifically, high behavioral entrainment was associated with self-other integration, as indexed by alpha suppression. Conversely, low behavioral entrainment encouraged reliance on internal knowledge and thus led to self-other segregation, indexed by alpha enhancement. These findings suggest that alpha oscillations index the processing of information about self and other depending on the compatibility of internal knowledge and external (environmental) events at finely resolved timescales.

Neural networks for harmonic structure in music perception and action

The ability to predict upcoming structured events based on long-term knowledge and contextual priors is a fundamental principle of human cognition. Tonal music triggers predictive processes based on structural properties of harmony, i.e., regularities defining the arrangement of chords into well-formed musical sequences. While the neural architecture of structure-based predictions during music perception is well described, little is known about the neural networks for analogous predictions in musical actions and how they relate to auditory perception. To fill this gap, expert pianists were presented with harmonically congruent or incongruent chord progressions, either as musical actions (photos of a hand playing chords) that they were required to watch and imitate without sound, or in an auditory format that they listened to without playing. By combining task-based functional magnetic resonance imaging (fMRI) with functional connectivity at rest, we identified distinct sub-regions in right inferior frontal gyrus (rIFG) interconnected with parietal and temporal areas for processing action and audio sequences, respectively. We argue that the differential contribution of parietal and temporal areas is tied to motoric and auditory long-term representations of harmonic regularities that dynamically interact with computations in rIFG. Parsing of the structural dependencies in rIFG is co-determined by both stimulus- or task-demands. In line with contemporary models of prefrontal cortex organization and dual stream models of visual-spatial and auditory processing, we show that the processing of musical harmony is a network capacity with dissociated dorsal and ventral motor and auditory circuits, which both provide the infrastructure for predictive mechanisms optimising action and perception performance.

Syntax in action has priority over movement selection in piano playing: An erp study

Complex human behavior is hierarchically organized. Whether or not syntax plays a role in this organization is currently under debate. The present ERP study uses piano performance to isolate syntactic operations in action planning and to demonstrate their priority over nonsyntactic levels of movement selection. Expert pianists were asked to execute chord progressions on a mute keyboard by copying the posture of a performing model hand shown in sequences of photos. We manipulated the final chord of each sequence in terms of Syntax (congruent/incongruent keys) and Manner (conventional/unconventional fingering), as well as the strength of its predictability by varying the length of the Context (five-chord/two-chord progressions). The production of syntactically incongruent compared to congruent chords showed a response delay that was larger in the long compared to the short context. This behavioral effect was accompanied by a centroparietal negativity in the long but not in the short context, suggesting that a syntax-based motor plan was prepared ahead. Conversely, the execution of the unconventional manner was not delayed as a function of Context and elicited an opposite electrophysiological pattern (a posterior positivity). The current data support the hypothesis that motor plans operate at the level of musical syntax and are incrementally translated to lower levels of movement selection.

Saliency detection as a reactive process: unexpected sensory events evoke cortico-muscular coupling

Survival in a fast-changing environment requires animals not only to detect unexpected sensory events, but also to react. In humans, these salient sensory events generate large electrocortical responses, which have been traditionally interpreted within the sensory domain. Here we describe a basic physiological mechanism coupling saliency-related cortical responses with motor output. In four experiments conducted on 70 healthy participants, we show that salient substartle sensory stimuli modulate isometric force exertion by human participants, and that this modulation is tightly coupled with electrocortical activity elicited by the same stimuli. We obtained four main results. First, the force modulation follows a complex triphasic pattern consisting of alternating decreases and increases of force, time-locked to stimulus onset. Second, this modulation occurs regardless of the sensory modality of the eliciting stimulus. Third, the magnitude of the force modulation is predicted by the amplitude of the electrocortical activity elicited by the same stimuli. Fourth, both neural and motor effects are not reflexive but depend on contextual factors. Together, these results indicate that sudden environmental stimuli have an immediate effect on motor processing, through a tight corticomuscular coupling. These observations suggest that saliency detection is not merely perceptive but reactive, preparing the animal for subsequent appropriate actions. SIGNIFICANCE STATEMENT Salient events occurring in the environment, regardless of their modalities, elicit large electrical brain responses, dominated by a widespread “vertex” negative-positive potential. This response is the largest synchronization of neural activity that can be recorded from a healthy human being. Current interpretations assume that this vertex potential reflects sensory processes. Contrary to this general assumption, we show that the vertex potential is strongly coupled with a modulation of muscular activity that follows the same pattern. Both the vertex potential and its motor effects are not reflexive but strongly depend on contextual factors. These results reconceptualize the significance of these evoked electrocortical responses, suggesting that saliency detection is not merely perceptive but reactive, preparing the animal for subsequent appropriate actions.

The E-music box: an empirical method for exploring the universal capacity for musical production and for social interaction through music

Humans are assumed to have a natural—universal—predisposition for making music and for musical interaction. Research in this domain is, however, typically conducted with musically trained individuals, and therefore confounded with expertise. Here, we present a rediscovered and updated invention—the E-music box—that we establish as an empirical method to investigate musical production and interaction in everyone. The E-music box transforms rotatory cyclical movements into pre-programmable digital musical output, with tempo varying according to rotation speed. The user’s movements are coded as continuous oscillatory data, which can be analysed using linear or nonlinear analytical tools. We conducted a proof-of-principle experiment to demonstrate that, using this method, pairs of non-musically trained individuals can interact according to conventional musical practices (leader/follower roles and lower-pitch dominance). The results suggest that the E-music box brings ‘active’ and ‘interactive’ musical capacities within everyone’s reach. We discuss the potential of this method for exploring the universal predisposition for music making and interaction in developmental and cross-cultural contexts, and for neurologic musical therapy and rehabilitation.

Dynamical entrainment of corticospinal excitability during rhythmic movement observation : a Transcranial Magnetic Stimulation study

Spontaneous modulations of corticospinal excitability during action observation have been interpreted as evidence for the activation of internal motor representations equivalent to the observed action. Alternatively or complementary to this perspective, growing evidence shows that motor activity during observation of rhythmic movements can be modulated by direct visuomotor couplings and dynamical entrainment. In‐phase and anti‐phase entrainment spontaneously occur, characterized by cyclic movements proceeding simultaneously in the same (in‐phase) or opposite (anti‐phase) direction. Here we investigate corticospinal excitability during the observation of vertical oscillations of an index finger using Transcranial Magnetic Stimulation (TMS). Motor‐evoked potentials (MEPs) were recorded from participants’ flexor and extensor muscles of the right index finger, placed in either a maximal steady flexion or extension position, with stimulations delivered at maximal flexion, maximal extension or mid‐trajectory of the observed finger oscillations. Consistent with the occurrence of dynamical motor entrainment, increased and decreased MEP responses – suggesting the facilitation of stable in‐phase and anti‐phase relations but not an unstable 90° phase relation – were found in participants’ flexors. Anti‐phase motor facilitation contrasts with the activation of internal motor representation as it involves activity in the motor system opposite from activity required for the execution of the observed movement. These findings demonstrate the relevance of dynamical entrainment theories and methods for understanding spontaneous motor activity in the brain during action observation and the mechanisms underpinning coordinated movements during social interaction.