A new study conducted by researchers at the University of Oxford has challenged previously held views that brain preservation in the archaeological record is extremely rare. The team carried out the largest study to date of the global archaeological literature about preserved human brains to compile an archive that exceeds 20-fold the number of brains previously compiled. The findings have been published today in the Proceedings of the Royal Society B.

Neuroscientists have taken a step closer to understanding those moments when our thoughts seem to vanish into thin air, a phenomenon known as “mind blanking.” A study published in The Journal of Neuroscience reveals that when people report having no identifiable thoughts — mind blanking — there is a marked reduction in brain activity across several key regions. This intriguing discovery contributes to broader conversations about consciousness and our ability to report experiences.

The authors behind the new study sought to better understand a relatively understudied area of cognitive neuroscience: the phenomenon of mind blanking, where individuals find themselves unable to recount their immediate-past mental content. Unlike mental states with reportable content, such as daydreaming or engaging in a task, mind blanking represents a unique state of consciousness that lacked thorough neural characterization.

“In the past 10 years, I have researched human unconscious states where communication is restricted (post-comatose disorders),” said corresponding author Athena Demertzi, a tenured research associate of the Belgian Fund for Scientific Research and director of the Physiology of Cognition Lab at the University of Liège, Belgium.

Here we show that DS2 is an online, synchronous population event accompanied by widespread increases in neural activity and brief arousalions. On the basis of the stationary activation of place cells with fields close to the mouse’s current location, we propose that DS2 may serve as a mechanism to regularly ground the hippocampal representation of position in an environment during immobility. Rapidly switching between current (DS2) and remote (SPW-R) locations would enable cognitive flexibility that varies with sudden changes in the animal’s internal state or changes in the environment (for example, a startling noise). Synchronous neural activity during DS2 may provide opportunity windows for synaptic plasticity, consistent with our findings linking DS2 to associative memory formation.

At the microcircuit level, distinct brain states are shaped by the non-uniform recruitment of local inhibitory cells, which are key for directing information flow²⁷. As arousal-activated AACs heterogeneously innervate principal cells^19,20 and are highly active during DS2 but mostly silent during SPW-Rs, this GABAergic cell (and probably others, such as TORO cells) may be important in regulating the distinct ensemble activity between DS2 and SPW-Rs. At a network level, DS2 is thought to be primarily triggered by the medial entorhinal cortex, which contains neurons that encode self-referenced movement variables, locations and environmental borders^28,29,30. This self-referenced spatial input may indeed be key for recruiting spatially tuned hippocampal cells corresponding to an animal’s current position during DS2. Both tones and air puffs reliably evoked DS2 and promoted current position encoding, but the identity of the stimulus (tone versus puff) could not be reliably decoded.