Thinking in sync: How brain rhythms support intelligence

(Press-News.org) When the brain is under pressure, certain neural signals begin to move in sync – much like a well-rehearsed orchestra. A new study from Johannes Gutenberg University Mainz (JGU) is the first to show how flexibly this neural synchrony adjusts to different situations and that this dynamic coordination is closely linked to cognitive abilities. "Specific signals in the midfrontal brain region are better synchronized in people with higher cognitive ability – especially during demanding phases of reasoning," explained Professor Anna-Lena Schubert from JGU's Institute of Psychology, lead author of the study recently published in the Journal of Experimental Psychology: General.

The researchers focused on the midfrontal area of the brain and the measurable coordination of the so-called theta waves. These brainwaves oscillate between four and eight hertz and belong to the group of slower neural frequencies. "They tend to appear when the brain is particularly challenged such as during focused thinking or when we need to consciously control our behavior," said Schubert, who heads the Analysis and Modeling of Complex Data Lab at JGU.

Being able to focus even next to a buzzing phone

The 148 participants in the study, aged between 18 and 60, first completed tests assessing memory and intelligence before their brain activity was recorded using electroencephalography (EEG). This method measures tiny electrical signals in the brain using electrodes placed on the scalp and is a well-established technique for gaining precise insights into cognitive processes. During EEG recording, participants completed three mentally demanding tasks designed to assess cognitive control.

The researchers were interested in the participants' ability to flexibly shift between changing rules, which is an essential aspect of intelligent information processing. For example, participants had to press a button to decide whether a number was even or odd, and moments later whether it was greater or less than five. Each switch of rules required rapid adjustment of mental strategies – a process that allowed researchers to closely observe how the brain's networks coordinate in real time.

As a result, individuals with higher cognitive abilities showed especially strong synchronization of theta waves during crucial moments, particularly when making decisions. Their brains were better at sustaining purposeful thought when it mattered most. "People with stronger midfrontal theta connectivity are often better at maintaining focus and tuning out distractions, be it that your phone buzzes while you're working or that you intend to read a book in a busy train station," explained Schubert.

A flexible rhythm in the brain

Professor Anna-Lena Schubert was particularly surprised by how closely this brain rhythm coordination was tied to cognitive abilities. "We did not expect the relationship to be this clear," she said. What mattered most was not continuous synchronization, but the brain's ability to adapt its timing flexibly and contextually – like an orchestra that follows a skilled conductor. The midfrontal region often sets the tone in this coordination but works in concert with other areas across the brain. This midfrontal theta connectivity appears to be particularly relevant during the execution of decisions, however not during the preparatory mental adjustment to new task rules.

Previous EEG studies on cognitive ability mostly examined activity in isolated brain regions. In contrast, this study took a network-level approach, examining how different areas interact across multiple tasks to identify stable, overarching patterns. The findings show that individual differences in cognitive ability are linked to the brain's dynamic network behavior.

"Potential applications such as brain-based training tools or diagnostics are still a long way off," emphasized Schubert. "But our study offers important groundwork for understanding how intelligence functions at a neural level." A follow-up study, now seeking participants aged 40 and older from the Rhine-Main region, will explore which biological and cognitive factors further support this kind of efficient brain coordination and the role of additional cognitive abilities, such as processing speed and working memory.

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