A human brain manages the complex processing required for abstract reasoning by coordinating different areas across various time scales. While scientists have long localized certain cognitive functions to specific regions, new research explores how the “rhythm” of the brain, its complexity and connectivity, relates to how effectively a person performs during active intelligence testing. This study examines whether the coordination between these areas is associated with individual levels of cognitive ability.Beyond IQ Scores: New Study Reveals the Neural Rhythm of Intelligence. Image by FreepikA new study published in the journal Communications Biology investigates the neural mechanisms underlying human intelligence. Published on December 23, 2025, the research treats intelligence as a multilayer phenomenon that occurs across different scales of time and space. Led by Jonas A. Thiele and Kirsten Hilger, the research team examined how the connectedness of brain regions and the complexity of neural signals relate to performance on a standardized intelligence test.The study involved an international collaboration of researchers from the following institutions:Jonas A. Thiele & Kirsten Hilger: Department of Psychology I, University of Würzburg, GermanyJoshua Faskowitz & Olaf Sporns: Department of Psychological and Brain Sciences, Indiana University, Bloomington, USAAdam Chuderski: Centre for Cognitive Science, Jagiellonian University, Krakow, PolandRex Jung: Department of Psychology, The University of New Mexico, Albuquerque, NM, USAKirsten Hilger: Also affiliated with the Department of Psychology, Differential Psychology, Personality Psychology and Psychological Diagnostics, Vinzenz Pallotti University Vallendar, Vallendar, GermanyWhat the Researchers InvestigatedThe primary goal of this study was to provide the first empirical test of the “Multilayer Processing Theory” (MLPT) of intelligence. This theory suggests that intelligence is not located in one single spot but emerges from hierarchical layers of processing. According to the MLPT, brain processes at multiple scales contribute to how a person thinks and solves problems.The researchers focused on two main scientific ideas:Global Coordination (Macroscale): The theory assumes that higher intelligence is associated with more flexible “long-range” processes. These are communications between distant brain regions, such as the frontal and parietal lobes, which are thought to operate at slower temporal scales.Local Processing (Microscale): The theory proposes that higher intelligence may be associated with simpler short-range processes. These subprocesses take place within localized neuronal assemblies and operate at faster temporal scales.By using two different types of brain imaging – fMRI and EEG – the team aimed to examine how these different “layers” of brain activity are related to intelligence test performance.How the Study Was ConductedThe researchers analyzed datasets from two independent laboratories to capture complementary aspects of brain function.The fMRI Group (Sample 1): This group consisted of 67 participants. Functional magnetic resonance imaging (fMRI) was used to examine slower patterns of communication between brain regions. Participants were scanned while resting and while solving items from Raven’s Progressive Matrices (RPM), a standard test of fluid intelligence. The researchers used graph-theoretical measures to assess how strongly (degree) and how broadly (participation coefficient) different brain regions were connected during the task.The EEG Group (Sample 2): This group included 131 participants. Electroencephalography (EEG) was used to capture faster brain dynamics. As in the first group, participants were recorded during rest and during the RPM intelligence test. The researchers applied a method called multiscale entropy (MSE) to quantify the complexity of brain signals across 20 different temporal scales.In both groups, the researchers subtracted resting-state activity from task-related activity to isolate processes specifically associated with problem-solving during the intelligence test.What Makes This Study NewThe authors note that many previous studies on intelligence have focused on brain activity at rest or during relatively simple tasks. In contrast, this study examines brain activity during performance on an established intelligence test.Additionally, earlier research has often relied on a single measurement method. By combining fMRI (spatial information) and EEG (temporal information), this study adopts a multiscale approach to investigating human cognition. The authors describe their work as providing empirical evidence for key assumptions of the Multilayer Processing Theory.Key Findings from the StudyThe study reports several findings regarding how brain activity relates to intelligence test performance:Connections in Frontal and Parietal Regions: The fMRI analyses showed that higher intelligence scores were associated with more diverse inter-network connections (higher participation coefficient) in specific frontal and parietal brain regions. These regions exhibited broader communication with other brain systems during the task.Long-Range Processes and Signal Complexity: The EEG analyses revealed that higher intelligence scores were significantly associated with greater signal complexity at slower (coarser) temporal scales. According to the authors, this pattern may reflect more flexible long-range neural processes.Short-Range Processes (Trend-Level Finding): At faster (finer) temporal scales, there was a non-significant trend suggesting that higher intelligence scores might be associated with lower signal complexity in some regions. The authors note that this finding requires further investigation.Task-Related Reconfiguration: Brain regions associated with intelligence also showed notable changes in their connectivity patterns when participants transitioned from rest to active problem-solving.Authors’ ConclusionsThe authors conclude that higher intelligence is associated with differences in how brain networks are organized and coordinated across multiple temporal and spatial scales. In particular, they highlight the role of fronto-parietal regions in maintaining diverse connections with other brain networks.They suggest that long-range processes, reflected in more complex activity at slower timescales, may reflect coordination of shorter-range processes during cognitive tasks.The study also identifies several limitations. The sample sizes were relatively modest, which may limit the detection of smaller effects. Because the fMRI and EEG datasets were collected from different groups, the results could not be directly compared within the same individuals. In addition, participants were primarily young adults, which may limit generalizability to other age groups.The authors recommend that future research use methods such as magnetoencephalography (MEG), which can capture both spatial and temporal characteristics of brain activity in a single sample.Summary of the Study (Simplified)This study examines how brain activity during intelligence testing differs in relation to test performance.Key points reported in the study include:Higher intelligence scores were associated with more distributed communication between brain regions, particularly in frontal and parietal areas.Greater signal complexity at slower timescales was observed in individuals with higher test scores, which the authors suggest may reflect long-range neural processes.At faster timescales, a non-significant trend toward lower complexity was observed, which the authors note requires further investigation.Overall, the findings indicate that intelligence test performance is associated with patterns of interaction between brain regions across multiple temporal and spatial scales.Understanding the Broader ContextThese findings contribute to ongoing research on how the brain operates as a dynamic network. Rather than focusing on isolated regions, this study emphasizes the importance of interactions between distributed brain systems across multiple timescales. The results are consistent with theoretical models, such as the Parieto-Frontal Integration Theory (P-FIT), that highlight the role of frontal and parietal regions in complex cognitive processes.ConclusionThis study shows that performance on intelligence tests is associated with patterns of communication between brain regions, particularly through long-range connections across different brain networks. It also highlights the role of signal complexity at different temporal scales in understanding these processes.While the findings support a multiscale perspective on intelligence, further research is needed to clarify how these neural dynamics operate across populations and experimental contexts.The information in this article is provided for informational purposes only and is not medical advice. For medical advice, please consult your doctor.Explore Similar Cognitive TasksThe intelligence test used in this study is based on pattern recognition tasks such as Raven’s Progressive Matrices. You can explore similar types of cognitive assessments here.ReferenceThiele, J. A., Faskowitz, J., Sporns, O., Chuderski, A., Jung, R., & Hilger, K. (2025). Decoding the human brain during intelligence testing. Communications Biology, 9(90). https://doi.org/10.1038/s42003-025-09354-4The post New Study: Brain “Teamwork” Decodes Individual Intelligence Scores appeared first on CogniFit Blog: Brain Health News.