Biology subjects

Belloli, L.

Publications and source records attributed to Belloli, L..

3 recordsLinked to original sources

bioRxiv2024

Mind the blank: behavioral, experiential, and physiological signatures of absent-mindedness

Does being awake necessarily mean being conscious of something? This study investigates the phenomenon of Mind Blanking (MB), characterized by an "emptiness of mind", comparing it with Mind Wandering (MW) and On-task (ON) states. Using a sustained attention task and electroencephalogram monitoring, behavioral and neurophysiological signatures of MB were examined in 62 participants. MB exhibited a specific pattern of behavioral lapses, as well as decreased fast oscillatory activity and complexity over posterior electrodes compared to MW. Functional connectivity analyses revealed decreased long-range inter-areal connectivity during MB, compared to both ON and MW states. Event-related potentials with source reconstruction and temporal decoding techniques indicated a significant disruption in visual processing during MB, starting from 200 ms post stimulus and echoing into the late-stage of visual processing, suggesting a disruption of conscious access to sensory information during MB. EEG-derived markers allowed the prediction of mental states at the trial level, offering a finer view of conscious dynamics than subjective reports alone. Overall, these findings challenge the notion of the wakeful conscious mind as inherently content-oriented, suggesting that MB reflects genuine gaps in the stream of conscious thoughts, arising from disruptions in the generation or accessibility of thought content. SIGNIFICANCE STATEMENTEmploying cutting-edge neurophysiological techniques on high-density electroencephalographic recordings, our study unveils unique neurophysiological markers of mind blanking, a phenomenon characterized by lapses in conscious content amidst the flow of wakeful consciousness. Distinguished from content-oriented states such as on-task and mind-wandering, mind blanking appears to be a distinct mental state. Furthermore, we demonstrate the feasibility of decoding consciousness dynamics solely from EEG features, transcending the limitations of intermittent subjective reports. Our findings thus not only provide a novel framework for investigating the stream of consciousness but also challenge the conventional notion that wakefulness invariably signifies being conscious of something.

neuroscience↗

bioRxiv2023

Whole-brain modelling supports the use of serotonergic psychedelics for the treatment of disorders of consciousness

Disorders of consciousness (DoC) are a challenging and complex group of neurological conditions characterised by absent or impaired awareness. The current range of therapeutic options for DoC patients is limited, offering few non-invasive pharmacological alternatives. This situation has sprung a growing interest in the development of novel treatments, such as the proposal to study the efficacy of 5HT2A receptor agonists (also known as psychedelics) to restore impaired consciousness. Given the ethical implications of exploring novel compounds in non-communicative individuals, we assessed in silico their effects in the whole-brain dynamics of DoC patients. We embedded the whole-brain activity of patients in a low-dimensional space, and then used this representation to visualise the effects of simulated neuromodulation across a range of receptors representing potential drug targets. Our findings show that activation of serotonergic and opioid receptors shifted brain dynamics of DoC patients towards patterns typically seen in conscious and awake individuals, and that this effect was mediated by the brain-wide density of activated receptors. These results showcase the role of whole-brain models in the discovery of novel pharmacological treatments for neuropsychiatric conditions, while also supporting the feasibility of accelerating the recovery of consciousness with serotonergic psychedelics.

neuroscience↗

bioRxiv2023

Heartbeat-evoked potential and ongoing brain dynamics during interoceptive and exteroceptive information processing predict attentional focus

Attention shapes our consciousness content and perception by increasing the probability of becoming aware and, or, better encode a selection of the incoming inner or outer sensory world. We designed a task to engage interoceptive and exteroceptive attention by orienting healthy participants to their heartbeats or auditory stimuli and investigated whether brain dynamics (Kolmogorov complexity - KC, permutation entropy - PE, weighted symbolic mutual information - wSMI, power spectrum density - PSD) and the heartbeat-evoked potential (HEP) distinguished interoceptive from exteroceptive covert attention. Exteroceptive attention yielded an overall flattening of the PSD, whereas during interoceptive attention there was a decrease in complexity, an increase in frontal connectivity and oscillations in the theta range, and a modulation of the HEP. Subject-level classifiers based on HEP features classified the attentional state of 17/20 participants. KC, PE, and wSMI showed comparable accuracy in classifying exteroceptive-interoceptive attention and exhibited a synergic behavior with the HEP features. PSD features demonstrated exceptional performance (20/20). Command-following was assessed in 5 brain-injured patients with a modified version of the task. An Unresponsive Wakefulness Syndrome/Vegetative State patient and a locked-in syndrome patient demonstrated a willful modulation of the HEP and the patient-level classifiers suggest that patients were complying with task instructions. Our findings show that directing attention to bodily rhythms or external stimuli elicits distinct neural responses that can be employed to track covert attention at the individual level. Importantly, the brain markers studied in this work provide multiple layers to explore information processing in disorders of conscious patients. Significance statementWe show that directing attention to bodily rhythms or external stimuli induces specific neural responses, allowing for individual-level tracking of covert attention in healthy participants. The time-locked and dynamical brain markers identified as relevant to distinguish between interoceptive-exteroceptive attention were further assessed in a small cohort of brain-injured patients as an EEG proxy of command-following. We show for the first time the willful modulation of the HEP in an UWS/VS patient and a locked-in syndrome patient, along with significant classification accuracies when combining the explored features. Importantly, the brain markers studied in this work provide multiple layers to explore information processing in disorders of conscious patients, and expand the framework of heart-brain interactions employed for diagnostic purposes.

neuroscience↗