Every day, our brain directs attention toward whatever stands out or seems most relevant. This explains why a traffic sign might go unnoticed while we are walking, but not when we are driving. In the brain, the networks that allow us to attend to relevant information in space are well known and include regions of the parietal and frontal lobes. But what would happen if we temporarily interfered with one of these regions?
In a study carried out at the Brain, Mind and Behavior Research Center (CIMCYC), we explored, in a large sample of participants, how neuromodulation with transcranial magnetic stimulation applied to a parietal region of the brain could modulate our attentional capacity. Transcranial magnetic stimulation is a technique that delivers brief magnetic pulses to temporarily modulate the activity of specific brain regions. Because it is non-invasive and safe, it allows controlled alteration of the functioning of a particular area, thereby helping us better understand the brain mechanisms that support different cognitive processes.
Results showed that brain stimulation modulated spatial attention. However, these effects were not the same for everyone. To better understand the causes of this variability, the researchers examined white matter, that is, the “wiring” that connects different brain regions and allows information to flow efficiently between them. Our study showed that part of the differences in neuromodulation effects depended on the integrity of that wiring. In general terms, individuals with greater integrity in certain fiber tracts showed a smaller effect of neuromodulation, while greater integrity in some pathways was associated with a reduced impact. This suggested that the effectiveness of neuromodulation partly depended on how each person’s brain communication pathways were organized and connected.
These findings not only help explain why neuromodulation does not act the same way in everyone, but also highlight the importance of considering differences in white matter to move toward more personalized and effective interventions. Moreover, they emphasize that combining techniques such as transcranial magnetic stimulation with measures of white matter provides a more complete picture of how each brain processes and prioritizes information, opening new avenues for future research and clinical applications.
Reference
Ramírez-Guerrero, J. J., Narganes-Pineda, C., Martín-Signes, M., & Chica, A. B. (2025). Exploring the causal involvement of the rIPL and white matter interindividual variability in orienting and consciousness. https://doi.org/10.1016/j.neuroimage.2025.121137
Contact
Joaquín Ramírez Guerrero - joaramgue@ugr.es