Campioni, L. | bioRxiv Science

bioRxiv2018

Spectral and topological analysis of the cortical representation of the head position: does hypnotizability matter?

The aim of the study was to assess the EEG correlates of head positions, which have never been studied in humans, in participants with different psychophysiological characteristics, as encoded by their hypnotizability scores. This choice is motivated by earlier studies suggesting different processing of the vestibular/neck proprioceptive information in subjects with high (highs) and low (lows) hypnotizability scores maintaining their head rotated toward one side (RH). We analysed EEG signals recorded in 20 highs and 19 lows in basal conditions (head forward) and during RH, using spectral analysis, which captures changes localized to specific recording sites, and Topological Data Analysis (TDA), which instead describes large-scale differences in processing and representing sensorimotor information. Spectral analysis revealed significant differences related to the head position for alpha1, beta2, beta3, gamma bands, but not to hypnotizability. TDA instead revealed global hypnotizability-related differences in the strengths of the correlations among recording sites during RH. Significant changes were observed in lows on the left parieto-occipital side and in highs in right fronto-parietal region. Significant differences between the two groups were found in the occipital region, where changes were larger in lows than in highs. The study reports findings of the EEG correlates of the head posture for the first time, indicates that hypnotizability modulates its representation/processing on large-scale and that spectral and topological data analysis provide complementary results.

neuroscience↗

bioRxiv2018

Topology highlights mesoscopic functional equivalence between imagery and perception

The functional equivalence between mental images and perception or motion has been proposed on the basis of neuroimaging evidence of large spatially overlapping activations between real and imagined sensori-motor conditions. However, similar local activation patterns do not imply the same mesoscopic integration of brain regions active during imagery and perception or action. Here we present the first EEG evidence of topological equivalence between functional network organization at intermediate and global scales during tasks. We show that the degree of functional equivalence varies in the population and is associated with different magnitudes in the restructuring of the functional connectivity between imagery and real tasks. In particular, changes observed during imagery with respect to basal conditions account for the cognitive effort experienced during imagery, and subjects characterized by stronger functional equivalence exhibit smaller topological deviations in the imagination tasks performed after real tasks, thus showing learning effects. Altogether, our findings point to different sensori-cognitive information processing in the subjects showing different functional equivalence. We anticipate our results to be a starting point for a novel dynamical description of functional equivalence, which will be relevant for socio-cognitive theories of embodiment and cognitive formulations of how different selves emerge from neurophysiological assets.

neuroscience↗