Beeinflussung kognitiver Verarbeitung durch Echtzeit-EEG getriggerte Transkranielle Magnetstimulation
Kognitive, systemische und Verhaltensneurobiologie
Zusammenfassung der Projektergebnisse
The objective of the present project was to investigate the possibility of modulating cognitive output in real-time by using non-invasive brain stimulation (transcranial magnetic stimulation - TMS) coupled with real-time electroencephalogram (EEG), delivering cortical stimuli during specific phases of a physiologically relevant neuronal oscillation, namely prefrontal theta band oscillation (4-7Hz). The relevance of prefrontal theta oscillation in cognition was established in several studies, as synchronicity between the prefrontal cortex and other brain regions within this frequency are associated with improved cognitive performance. Moreover, different phases of this oscillation are associated with increased neuronal firing and neuroplasticity, suggesting its importance in information transfer and memory formation. In the first experiment I used brain state-dependent EEG-triggered transcranial magnetic stimulation (TMS) to target predefined phases of the prefrontal theta oscillation, aiming to modulate working memory performance of healthy human subjects in real time. As in previous studies, for the real-time phase detection and estimation I used individualized spatial filters based on the MRI and EEG recording of each subject, then source-projecting theta oscillations in the prefrontal cortical area. TMS applied during the trough of the prefrontal theta oscillation did not affect working memory performance in comparison to TMS at random time-points, either by targeting the right posterior-parietal cortex or the left dorsomedial prefrontal cortex. These findings go against the report by Berger et al. 2019, which only used random stimulation and a post-hoc phase estimation to correlate theta phase TMS and cognitive output. These discrepancies suggest the need to revisit the current understandings of neuronal oscillations in working memory function, as well as the methods of brain state-dependent EEG-TMS. In the second experiment I used brain state-dependent EEG-TMS in healthy human subjects during working memory execution aiming to induce long-term neuromodulatory changes. In this experiment I compared the working memory performance prior and after brain statedependent EEG-TMS sessions. I observed that applying TMS to the prefrontal cortex during the trough of the alpha oscillation simultaneously to the execution of a working memory task enhanced cognitive performance compared to other sessions. Interestingly, this was observed only when synchronizing stimuli to the alpha oscillation, not theta. These observations suggest that cortical oscillation may have different roles depending on the brain state (“working memory” vs. rest and “alpha” vs “theta” oscillation), while also suggesting that combining task execution with state-dependent stimulation may considerably increase the effectiveness of TMS protocols designed to induce long-term neuromodulation and cognitive enhancement.
Projektbezogene Publikationen (Auswahl)
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International Conference of Cognitive Neuroscience, Helsinki, 2022; “Brainstate-dependent plasticity induction in human dorsomedial prefrontal cortex” (Gordon PC).
Gordon, Pedro Caldana
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Organization for Human Brain Mapping Annual Meeting of 2022, Glasgow. “Identifying direct cortical EEG responses to TMS via optimized sham procedure”.
Gordon, Pedro Caldana
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5th International Brain Stimulation conference, Lisbon 2023; “Repetitive TMS during specific phases of the dorsomedial prefrontal theta oscillation” (Gordon PC).
Gordon, Pedro Caldana
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Untangling TMS‐EEG responses caused by TMS versus sensory input using optimized sham control and GABAergic challenge. The Journal of Physiology, 601(10), 1981-1998.
Gordon, Pedro Caldana; Song, Yu Fei; Jovellar, D. Blair; Rostami, Maryam; Belardinelli, Paolo & Ziemann, Ulf
