Stimulation of the right entorhinal white matter enhances visual memory encoding in humans

Mankin, Emily A.; Aghajan, Zahra M.; Schuette, Peter J; Tran, Michelle; Tchemodanov, Natalia; Titiz, Ali S.; Kalender, Güldamla; Eliashiv, Dawn; Stern, John M.; Weiss, Shennan A.; Kirsch, Dylan; Knowlton, Barbara J.; Fried, Itzhak; Suthana, Nanthia

doi:10.1016/j.brs.2020.11.015

Cited by 27 publications

(26 citation statements)

References 43 publications

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“…We could not offer a full accounting for why some stimulation targets yielded dramatic increases in theta power, while others appear to cause no discernible change in brain activity and yet others caused theta power decreases. Anecdotal evidence from single subjects suggests the proximity of stimulation to white matter may play a role, which intuitively aligns with expectations regarding the propagation of signals through the brain and recent behavioral evidence [47]. However, our population did not show a significant effect of white matter proximity e or functional connectedness e indicating that other factors dictate the efficaciousness of a stimulation site.…”

Section: Discussionsupporting

confidence: 88%

Theta-burst stimulation entrains frequency-specific oscillatory responses

et al. 2021

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Background: Brain stimulation has emerged as a powerful tool in human neuroscience, becoming integral to next-generation psychiatric and neurologic therapeutics. Theta-burst stimulation (TBS), in which electrical pulses are delivered in rhythmic bouts of 3e8 Hz, seeks to recapitulate neural activity seen endogenously during cognitive tasks. A growing literature suggests that TBS can be used to alter or enhance cognitive processes, but little is known about how these stimulation events influence underlying neural activity. Objective: Our study sought to investigate the effect of direct electrical TBS on mesoscale neural activity in humans by asking (1) whether TBS evokes persistent theta oscillations in cortical areas, (2) whether these oscillations occur at the stimulated frequency, and (3) whether stimulation events propagate in a manner consistent with underlying functional and structural brain architecture. Methods: We recruited 20 neurosurgical epilepsy patients with indwelling electrodes and delivered direct cortical TBS at varying locations and frequencies. Simultaneous iEEG was recorded from nonstimulated electrodes and analyzed to understand how TBS influences mesoscale neural activity. Results: We found that TBS rapidly evoked theta rhythms in widespread brain regions, preferentially at the stimulation frequency, and that these oscillations persisted for hundreds of milliseconds post stimulation offset. Furthermore, the functional connectivity between recording and stimulation sites predicted the strength of theta response, suggesting that underlying brain architecture guides the flow of stimulation through the brain. Conclusions: By demonstrating that cortical TBS induces frequency-specific oscillatory responses, our results suggest this technology can be used to directly and predictably influence the activity of cognitively-relevant brain networks.

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Section: Discussionsupporting

confidence: 88%

Theta-burst stimulation entrains frequency-specific oscillatory responses

et al. 2021

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“…We could not offer a full accounting for why some stimulation targets yielded dramatic increases in theta power, while others appear to cause no discernible change in brain activity and yet others caused theta power decreases. Anecdotal evidence from single subjects suggests the proximity of stimulation to white matter may play a role, which intuitively aligns with expectations regarding the propagation of signals through the brain and recent behavioral evidence 37 . However, our population did not show a signi cant effect of white matter proximity -or functional connectedness -indicating that other factors dictate the e caciousness of a stimulation site.…”

Section: Discussionsupporting

confidence: 75%

Theta-burst stimulation entrains frequency-specific oscillatory responses

Solomon

Sperling

Sharan

et al. 2021

Preprint

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Background: Brain stimulation has emerged as a powerful tool in human neuroscience, becoming integral to next-generation psychiatric and neurologic therapeutics. Theta-burst stimulation (TBS), in which electrical pulses are delivered in rhythmic bouts of 3-8 Hz, seeks to recapitulate neural activity seen endogenously during cognitive tasks. A growing literature suggests that TBS can be used to alter or enhance cognitive processes, but little is known about how these stimulation events influence underlying neural activity.Objective/Hypothesis: The goal of our study was to investigate the effect of direct electrical TBS on mesoscale neural activity in humans by asking (1) whether TBS evokes persistent theta oscillations in cortical areas, (2) whether these oscillations occur at the stimulated frequency, and (3) whether stimulation events propagate in a manner consistent with underlying functional and structural brain architecture.Methods: We recruited 20 neurosurgical epilepsy patients with indwelling electrodes and delivered direct cortical TBS at varying locations and frequencies. Simultaneous iEEG was recorded from non-stimulated electrodes and analyzed to understand how TBS influences mesoscale neural activity. Results: We found that TBS rapidly evoked theta rhythms in widespread brain regions, preferentially at the stimulation frequency, and that these oscillations persisted for hundreds of milliseconds post stimulation offset. Furthermore, the functional connectivity between recording and stimulation sites predicted the strength of theta response, suggesting that underlying brain architecture guides the flow of stimulation through the brain.Conclusions: By demonstrating that direct TBS induces frequency-specific oscillatory responses, our results suggest this technology can be used to directly and predictably influence the activity of cognitively-relevant brain networks.

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“…This choice was made to limit the scope to a purely distance measure. While there are exciting conclusions to be made relative to white matter tractography, connectivity, and stimulation [30,61,103], this data set did not have J o u r n a l P r e -p r o o f 45 consistent enough sampling of noninvasive scans mapping white matter (such as diffusion tensor imaging, or DTI). Further, both our approach and a companion study by Parmigiani et al [83] was to start from a naïve geometrically-focused perspective.…”

Section: Discussionmentioning

confidence: 98%

“…Trains of stimulation in grey matter were shown to be more effective at decreasing high frequency activity as opposed to stimulation in white matter, with stronger effects in the neocortex versus the medial temporal lobe [29]. Interestingly, though, white matter stimulation with trains (as opposed to grey matter stimulation) in the mesial temporal lobe can improve visual memory encoding [103]. Therefore, further work is needed to resolve the differences between low frequency voltage responses such as CCEP, high frequency responses (trains), and stimulation location.…”

Section: Discussionmentioning

confidence: 99%