Neuromodulatory effects of parietal high-definition transcranial direct-current stimulation on network-level activity serving fluid intelligence

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Tara D. Erker¹ (tara.erker@boystown.org), Yasra Arif¹, Jason A. John¹, Christine M. Embury¹, Kennedy A. Kress¹, Seth D. Springer^1,2, Hannah J. Okelberry¹, Alex I. Wiesman⁴, Tony W. Wilson^1,3; ¹Boys Town National Research Hospital, ²University of Nebraska Medical Center (UNMC), ³Creighton University, ⁴McGill University

Fluid intelligence (Gf) involves rational thinking skills and requires the integration of information from different cortical regions to resolve novel complex problems. The effects of noninvasive brain stimulation on Gf have been studied in attempts to improve Gf, however, such studies are rare and the few existing have reached conflicting conclusions. The parieto-frontal integration theory of intelligence (P-FIT) postulates that the parietal and frontal lobes play a critical role in Gf. To investigate the suggested role of parietal cortices, we applied high-definition transcranial direct current stimulation (HD-tDCS) to the left and right parietal cortices of thirty-nine healthy adults (age 19-33) for 20 minutes in three separate sessions (left active, right active, and sham). After completing the stimulation session, the participants completed a logical reasoning task based on Raven’s Progressive Matrices during magnetoencephalography (MEG). Significant neural responses at the sensor-level across all stimulation conditions were imaged using a beamformer. Whole-brain, spectrally-constrained functional connectivity was then computed to examine the network-level activity. Behaviorally, we found that participants were significantly more accurate following left compared to right parietal stimulation. Regarding neural findings, we found significant HD-tDCS montage-related effects in brain networks thought to be critical for P-FIT, including parieto-occipital, fronto-occipital, fronto-parietal, and occipito-cerebellar connectivity during task performance. In conclusion, our findings showed that left parietal stimulation improved abstract reasoning abilities relative to right parietal stimulation and support both P-FIT and the neural efficiency hypothesis.

Topic Area: THINKING: Reasoning