NEUROINTELLIGENCE · The Brain Dynamics of Human Fluid Intelligence

The Brain Dynamics of Human Fluid Intelligence

Human fluid intelligence (FI) is characterized by a structured sequence of cognition, resulting in efficient application of rules to novel problems. In the brain, metabolic neuroimaging and lesion studies have linked FI to a specific frontoparietal network, here called the multiple-demand (MD) network, comprising regions of lateral frontal, insular, dorsomedial frontal and parietal cortex. But how do MD functions determine FI across stages of cognition? My extensive expertise in electroencephalography (EEG) source analyses allowed me to assess time-resolved neural representations of novel rules in MD and perceptual cortex as a function of FI, as well as the causal impact of MD cortex on earliest stages of perceptual encoding and task-related retrieval of information from memory. Higher- and lower-intelligent subjects’ EEG and behavioral measures of novel rule implementation have been systematically analyzed. Non-invasive neural stimulation (transcranial magnetic stimulation (TMS)) was used in combination with EEG to draw causal conclusions on the specific role of MD cortices in human FI. This novel analysis approach has provided a new account on FI: one aspect of low FI is the dysfunctional early filtering and retrieval of task-relevant information from memory, due to lack of top-down control from MD cortices, leading to cognitive overload on later processing stages. The results of the two studies suggest that indeed higher intelligent subjects not only showed better task performance, but also stronger neural responses in an early time window of task processing in the right intraparietal cortex, a region known to be involved in semantic fact retrieval. TMS stimulation of this region improved performance of both higher and lower intelligent subjects, while specifically the lower intelligent subjects showed a boost in right intraparietal neural activation patterns in response to the TMS triple-pulse. This suggests that specific TMS-based interventions that aim to address the cognitive functions underlying FI may be especially beneficial for those who show deficits in this cognitive domain. The proposal’s outcomes are both of high academic and clinical interest. Understanding the brain signatures underlying FI is essential for more specific and cost-effective medical interventions. For example, decline of FI due to specific diseases or healthy ageing is strongly correlated with psychiatric conditions such as depression, which affect an increasing number of people in the ageing European population. Developing more targeted neuroscientific interventions in this area will reduce the duration and cost of other medical interventions, such as the treatment with psychopharmaca and psychotherapy.

Data: CORDIS, © European Union