Current Research in Neurobiology
January 1, 2022
Christopher J. Whyte, Jakob Hohwy, Ryan Smith
21 citations
Cognitive theories of consciousness link frontoparietal circuits to conscious access, but no-report paradigms challenge this by showing conscious accessibility without prefrontal cortex (PFC) activation. This paper presents a computational model based on active inference, treating working memory gating as a cognitive action. Simulating a visual masking task, the model shows that late P3b-like event-related potentials and increased PFC activity arise from the working memory demands of self-report generation. Removing reporting demands eliminates these late potentials and reduces PFC activity, reproducing no-report paradigm results. However, even without reporting, simulated PFC activity on visible trials still crosses the threshold for reportability, maintaining the link between PFC and conscious access. Thus, no-report paradigm evidence does not necessarily contradict cognitive theories.
Current Research in Neurobiology
January 1, 2022
Maria Kozhevnikov, Alina Veronika Irene Strasser, Elizabeth Mcdougal et al.
13 citations
Vajrayana (Tantric Buddhist) practices that modulate attentional control through arousal-driven influences, rather than through monitoring continuous thought processes as in mindfulness, produce distinct neural and physiological states. In 16 highly experienced practitioners, the generation stage (Yidam) and completion stage with sign (Tummo) induced parasympathetic withdrawal (arousal) and phasic alertness, seen as decreased high-frequency heart rate variability and increased alpha2 power. These states were later employed in Tantric Mahamudra, which led to high cortical excitability, non-selective focused attention, and reduced attentional control, with power reductions in all frequency bands except theta. In contrast, non-Tantric Mahamudra resembled mindfulness practices, with parasympathetic dominance, tonic alertness, and active monitoring, shown by increased alpha1 power and less pronounced decreases in other bands. A neurobiological model differentiating arousal-based and mindfulness-related practices is proposed.
Current Research in Neurobiology
August 1, 2022
D. Candia-Rivera
A review of theoretical and experimental evidence suggests that brain-heart interactions play a role in consciousness, emotion, and cognition. Research in patients with disorders of consciousness shows that observing these interactions can detect residual consciousness even without behavioral signs. Studies in healthy participants indicate that neural responses to heartbeats relate to perception and self-consciousness, and mathematical modeling of physiological dynamics reveals that emotion processing begins with ascending vagal inputs to the brain, followed by sustained bidirectional brain-heart interactions. The author advocates for methodological advances in estimating brain-heart interactions to better understand their role in the origin, levels, and contents of consciousness, highlighting potential non-linear, complex communication between brain and heartbeat dynamics.
Current Research in Neurobiology
January 1, 2022
Yiqing Lu, Julio Rodriguez-Larios
EEG complexity is generally reduced during mind wandering compared to breath focus states in novice meditation practitioners. The study compared EEG signal complexity during mind wandering and breath focus using three algorithms: Higuchi's fractal dimension, Lempel-Ziv complexity, and Sample entropy. Twenty-five participants were iteratively interrupted during breath focus meditation to report whether they were focusing on the breath or thinking about something else. The authors conclude that EEG complexity metrics can distinguish mind wandering from breath focus states and could be used in future EEG neurofeedback protocols to facilitate meditation practice.