The proposal included two neuroscientific projects, an EEG study as well as a combined EEG-TMS study. Those have been both completed, i.e. data of 40 volunteers were collected for each project, respectively, and the data have been analysed.
I used EEG and combined EEG-TMS to assess the specific role of the frontoparietal MD system in human FI. Specifically, I asked whether low FI may be due to the dysfunctional early memory retrieval of task-relevant information. Data from the first EEG project indeed suggest that first neural differences between higher and lower intelligent subjects specifically occur at early neural processing stages within the MD system: around 200 milliseconds post task-onset, right intraparietal cortex showed stronger neural responses for higher intelligent subjects (Figure 1A). This effect was specific, i.e. it neither occurred in other brain regions nor at a different point in time. Stronger neural signatures of higher intelligent subjects were accompanied by their significantly better task performance (Figure 1B), and lower numbers of missed targets significantly correlated with stronger neural responses in right intraparietal cortex (Figure 1C). The right intraparietal cortex has been frequently associated with processes of semantic memory retrieval, suggesting that better task performance measures in higher intelligent subjects were due to more efficient early memory retrieval of task-relevant information.
In the second project, the combined EEG-TMS study, TMS was used to stimulate right intraparietal cortex in the time interval in which neural differences between higher and lower intelligent subjects were observed in the first project, i.e. in the EEG study. The same task paradigm was used as in the first project. TMS stimulation evoked a strong neural response in that region. Interestingly, a stronger TMS induced boost in neural responses was specifically observed in the group of lower intelligent subjects in right parietal cortex (Figure 2A), suggesting that TMS had a stronger impact on this group, compared with higher intelligent subjects, who already showed relatively strong neural responses in right parietal cortex in no-TMS conditions (i.e. in the first EEG project). Higher intelligent subjects showed significantly better task performance across all conditions (i.e. with and without TMS stimulation) relative to lower intelligent subjects (Figure 2B), thus replicating results from the first EEG project. Strikingly, the right intraparietal TMS stimulation caused a significant improvement in task performance in both higher and lower intelligent subjects (Figure 2C). Considering the specific boot of neural responses in lower intelligent subjects, this novel evidence may suggest that right parietal TMS stimulation has an especially beneficial impact on the cognitive processes of lower intelligent subjects. Follow-up research will tell whether this applies as well to populations suffering from a decline in FI due to illness or natural ageing.
The current results have been presented on multiple conferences, namely the SAMBA conference in Salzburg 2018 and the OHBM conference in Rom 2019. Preliminary results have been also presented to the EU at the MSCA-IF monitoring at LMU in May 2019, and received a very positive feedback. Furthermore, a talk on the projects’ outcomes has been accepted for a symposium at the BIOMAG-2020 conference in August 2020 in Birmingham. A manuscript has been prepared for submission to a high-impact peer-reviewed journal, such as PLOS Biology or PNAS.
