Our reasoning and, more generally, cognitive abilities are the result of activity in brain networks that are often impaired in neuropsychiatric disorders such as epilepsy. Physics and information theory suggest that brain networks function optimally at a critical state between order and disorder. However, the experimental relationship between cognitive performance and this critical state, i.e. whether cognition really benefits from proximity to a critical state, has so far been elusive.

How did you approach the topic?
In this study, we recorded the electrical currents in the brains of 104 people with epilepsy over several days using intracranial EEG and determined the activity of the neuronal networks. We also assessed the patients' cognitive performance in various areas, such as language, attention and short-term memory. We also took a closer look at various factors that are known to have a negative impact on cognition.

What did you discover?
We were able to show that proximity to a critical state predicts cognitive performance in several areas. The further away the activity in the brain networks was from the optimal state between order and disorder, the worse the patients performed in the cognitive tests. Different factors that can have a negative impact on cognition, including epilepsy-typical brain activity, epilepsy medication and sleep-like episodes, all have the same effect: they all disrupt the (optimal) critical state.

What’s your takeaway?
Our results support the critical state hypothesis, i.e. that the brain can only function optimally if the nerve cells within brain networks work together neither too orderly nor too disorderly. Accordingly, limitations in cognitive abilities, e.g. in epilepsy, are associated with a deviation in brain activity from this state.

Figure: Schematic representation of a brain network: the brain can only perform optimally if the nerve cells interact in a way that is neither too organized nor too disorganized © Charité | Paul Manuel Müller

Source
Müller PM et al. Critical dynamics predicts cognitive performance and provides a common framework for heterogeneous mechanisms impacting cognition. PNAS 2025 Apr 03. doi: 10.1073/pnas.2417117122 Link
Charité press release

Contact
PD Dr. Christian Meisel
Berlin Institute of Health at Charité (BIH) and
Department of Neurology and Experimental Neurology
Charité – Universitätsmedizin Berlin