Drawing on minds canvas: Differences in cortical integration patterns between artists and non-artists

Our primary question was to learn whether mentally composing drawings of their own choice produce different brain electric features in artists and laymen. To this purpose, we studied multichannel electroencephalograph (EEG) signals from two broad groups (all participants were females): artists (professionally trained in visual arts) and non-artists (without any training in art). To assess the underlying synchronization, which is assumed to be the platform for general cognitive integration between different cortical regions, three measures inspired by nonlinear dynamical system theory were applied as follows: (1) index based on generalized synchronization; (2) index based on mean phase coherence; and (3) index of phase synchrony based on entropy. Results consistent over all three measures were as follows: comparing the tasks to rest, the artists showed significantly stronger short- and long-range delta band synchronization, whereas the non-artists showed enhancement in short-range beta and gamma band synchronization primarily in frontal regions; comparing the two groups during the tasks, the artists showed significantly stronger delta band synchronization and alpha band desynchronization than did the non-artists. Strong right hemispheric dominance in terms of synchronization was found in the artists. In artists, the higher synchrony in the low-frequency band is possibly due to the involvement of a more advanced long-term visual art memory and to extensive top-down processing. The results demonstrate that in artists, patterns of functional cooperation between cortical regions during mental creation of drawings were significantly different from those in non-artists

Musicians and the gamma band: a secret affair?

While listening to music, a significant high degree of phase synchrony in the γ frequency range globally distributed over the brain was found in subjects with musical training (musicians) compared with subjects with no such training (non-musicians). No significant differences were found in other EEG frequency bands. Listening to neutral text did not produce any significant differences in the degree of synchronization between these two groups. For musicians, left-hemispheric dominance was found during listening to music. The right hemisphere was found to be dominant for non-musicians in text listening. The high degree of synchronization in musicians could be due to their high ability to retrieve musical patterns from their acoustic memory, which is a cogent condition for both listening to and anticipating musical sounds

Enhanced phase synchrony in the electroencephalograph γ band for musicians while listening to music

Multichannel electroencephalograph signals from two broad groups, 10 musicians and 10 nonmusicians, recorded in different states (in resting states or no task condition, with eyes opened and eyes closed, and with two musical tasks, listening to two different pieces of music) were studied. Degrees of phase synchrony in various frequency bands were assessed. No differences in the degree of synchronization in any frequency band were found between the two groups in resting conditions. Yet, while listening to music, significant increases of synchronization were found only in the γ-frequency range (>30 Hz) over large cortical areas for the group of musicians. This high degree of synchronization elicited by music in the group of musicians might be due to their ability to host long-term memory representations of music and mediate access to these stored representations

Phase synchrony analysis of EEG during music perception reveals changes in functional connectivity due to musical expertise

Differences in functional and topographical connectivity patterns between two groups, musicians and non-musicians, during attentively listening to three different pieces of music and to a text of neutral content, were presented by means of EEG phase synchrony analysis in five standard frequency bands: delta (30 Hz). The degree of phase synchrony or phase coherence between EEG signals was measured by a recently developed index, which is more suitable than classical indices, like correlation or coherence, when dealing with nonlinear and nonstationary signals like EEG. Comparing the music listening task to rest or control condition, musicians showed increase in phase synchrony over distributed cortical areas, both near and distant, in delta, and most conspicuously in gamma frequency band, whereas non-musicians showed enhancement only in delta band. Further, the degree of phase synchrony in musicians was reduced during listening to text as compared to listening to music. Comparing the two groups during the listening tasks, the clear-cut difference was found in gamma band phase synchrony, which was significantly stronger in musicians while listening to every chosen piece of music, yet no large difference between these two groups was found while listening to the chosen text. Musicians also showed stronger higher order inter-frequency phase synchrony between delta band oscillations in anterior regions and gamma band oscillations in posterior regions. In addition, consistent left hemispheric dominance, in terms of the strength of phase synchrony, was observed in musicians while listening to music, whereas right hemispheric dominance was observed in non-musicians. These results suggest that professional training in music is able to elicit context-sensitive functional connectivity between multiple cortical regions resulting in different listening strategies to music

Shadows of artistry: cortical synchrony during perception and imagery of visual art

Functional and topographical differences between two groups, artists and non-artists, during the performances of visual perception and imagery of paintings were presented by means of EEG phase synchrony analysis. In artists as compared with non-artists, significantly higher phase synchrony was found in the high frequency beta and gamma bands during the perception of the paintings; in the low frequency bands (primarily delta), phase synchrony was mostly enhanced during imagery. Strong decreases in phase synchrony of alpha were found primarily in artists for both tasks. The right hemisphere was found to present higher synchrony than the left in artists, whereas hemispheric asymmetry was less significant in non-artists. In the artists, enhanced synchrony in the high frequency band is most likely due to their enhanced binding capabilities of numerous visual attributes, and enhanced synchrony in the low frequency band seems to be due to the higher involvement of long-term visual memory mostly in imagery. Thus, the analysis of phase synchrony from EEG signals yields new information about the dynamical co-operation between neuronal assemblies during the cognition of visual art

Interdependencies in the spontaneous EEG while listening to music

We studied the patterns of interdependency between different brain regions during the performance of higher cognitive functions. Our goal was to check the existence in these patterns of both task-related differences (e.g. listening to music vs. rest) and training-related differences (musicians vs. non-musicians). For this purpose, a non-linear measure, called similarity index (S.I.), was used to detect asymmetric interdependencies between different brain regions by means of EEG signals. Relatively active and passive regions of the brain were found where the degree of activity was represented by excited degrees of freedom. The S.I. obtained during listening to different kinds of music was compared statistically with the S.I. with eyes closed, and significant changes (P≤0.05) were entered into schematic brain maps. A topographical representation of the S.I. yielded differences in the interdependency while performing different cognitive tasks. The results demonstrate the occurrence of task-related differences in both groups of subjects. Furthermore, subjects with musical training possessed significantly higher degrees of interdependencies than such without musical training while listening to music but not to text. We conclude that the new measure can be successfully applied for studying the dynamical co-operation between cortical areas during higher cognitive functioning

Effective detection of coupling in short and noisy bivariate data

In the study of complex systems, one of the primary concerns is the characterization and quantification of interdependencies between different subsystems. In real-life systems, the nature of dependencies or coupling can be nonlinear and asymmetric, rendering the classical linear methods unsuitable for this purpose. Furthermore, experimental signals are noisy and short, which pose additional constraints for the measurement of underlying coupling. We discuss an index based on nonlinear dynamical system theory to measure the degree of coupling which can be asymmetric. The usefulness of this index has been demonstrated by several examples including simulated and real-life signals. This index is found to effectively disclose the nature and the degree of interactions even when the coupling is very weak and data are noisy and of limited length; by this way, new insight into the functioning of the underlying complex system is possible

Co-operation in the brain in higher cognitive functioning

We have analyzed the interdependencies between different regions of human brain during processing of different kinds of music by using multivariate EEG signals. In this study, a new index, called similarity index, SI was used, which unlike the traditional linear measures is able to provide information about the direction of the interdependency. Relatively active and passive regions of the brain were highlighted, where the measure of the activity was reflected by the excited degrees of freedom at a typical length scale. The SIs during each task were compared statistically and significant changes ($ple0.05$) were depicted in schematic maps of the brain. A topographical representation of the S.I. showed differences in the connectivity while listening to different pieces of music