bioRxiv Preprint Server
November 20, 2020
Mor Regev, Andrea R. Halpern, Adrian M. Owen et al.
preprint
When people imagine music they have previously memorized, the brain's auditory cortices show melody-specific activity patterns similar to those during actual listening. Functional MRI data from participants who memorized six one-minute instrumental pieces revealed that during silent imagery, these patterns reappeared in right associative auditory cortices. Adding rhythmic tapping while imagining extended the melody-specific neural patterns to both left and right associative cortices. The findings suggest that the contents of conscious auditory experience are encoded similarly during imagery and perception, and that rhythmic motion can enhance the reinstatement of neural patterns associated with complex sounds, supporting models of motor-to-sensory influences in auditory processing.
Entropy (Basel, Switzerland)
March 16, 2020
Nicholas J M Popiel, Sina Khajehabdollahi, Pubuditha M. Abeyasinghe et al.
Integrated information, a measure proposed by Integrated Information Theory as a correlate of conscious experience, behaves as an order parameter that undergoes a phase transition at the critical point in generalized Ising models of small neural networks. In simulations of 159 random, positively weighted five-node excitatory networks, integrated information peaked at the critical temperature, where its generalized susceptibility was maximal. At this point, the system was maximally receptive and responsive to perturbations of its own states. The findings show that integrated information can capture critical behavior in an empirical dataset derived from the generalized Ising model.
bioRxiv Preprint Server
January 15, 2019
Sina Khajehabdollahi, Pubuditha M. Abeyasinghe, Adrian M. Owen et al.
preprint
Using the critical Ising model of the brain, integrated information—a measure of consciousness—was measured in toy models of generic neural networks. Monte Carlo simulations were run on 159 random weighted networks analogous to small 5-node neural network motifs. Integrated information, as a type of order parameter like magnetism, undergoes a phase transition at the model's critical point, where the system's 'consciousness' is maximally susceptible to perturbations and on the boundary between ordered and disordered forms. This adds evidence that the emergence of consciousness coincides with self-organized criticality, evolution, the emergence of complexity, and the integration of complex systems.
Dian Lu, Adapa Ram, Robin Carhart-Harris et al.
The posterior precuneus, a key hub of the default mode network, sits at the boundary with the frontoparietal control network. Using a spatial-derivative approach across five pharmacological datasets including psychedelic and anaesthetic states, the authors show that measuring how functional connectivity changes along the precuneus's dorsal–ventral axis reveals the organization of these networks with greater anatomical specificity than connectivity alone. This functional gradient is systematically altered by consciousness level: its overall magnitude diminishes across all altered states of consciousness, while its spatial entropy increases under psychedelics but decreases under sedation. The findings suggest the precuneus embeds a continuous, anatomically constrained transition between large-scale networks sensitive to global brain-state dynamics.