Disruption of right posterior parietal cortex by continuous Theta Burst Stimulation alters the control of body balance in quiet stance

AbstractObjectives:Noninvasive brain stimulation methods, including high-definition transcranial direct current stimulation (HD-tDCS) and theta burst stimulation (TBS) have emerged as novel tools to modulate and explore brain function. However, the relative efficacy of these newer stimulation approaches for modulating cognitive functioning remains unclear. This study investigated the cognitive effects of HD-tDCS, intermittent TBS (iTBS) and prolonged continuous TBS (ProcTBS) and explored the potential of these approaches for modulating hypothesized functions of the left posterior parietal cortex (PPC).Methods:Twenty-two healthy volunteers attended four experimental sessions in a cross-over experimental design. In each session, participants either received HD-tDCS, iTBS, ProcTBS or sham, and completed cognitive tasks, including a divided attention task, a working memory maintenance task and an attention task (emotional Stroop test).Results:The results showed that compared to sham, HD-tDCS, iTBS and ProcTBS caused significantly faster response times on the emotional Stroop task. The effect size (Cohen’sd) wasd= .32 for iTBS (p< .001), .21 for ProcTBS (p= .01) and .15 for HD-tDCS (p= .044). However, for the performance on the divided attention and working memory maintenance tasks, no significant effect of stimulation was found.Conclusions:The results suggest that repetitive transcranial magnetic stimulation techniques, including TBS, may have greater efficacy for modulating cognition compared with HD-tDCS, and extend existing knowledge about specific functions of the left PPC.

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P2. Theta burst stimulation over left posterior parietal cortex interferes with imitation of gestures

Clinical Neurophysiology ◽

10.1016/j.clinph.2012.03.052 ◽

2012 ◽

Vol 123 (10) ◽

pp. e101-e102

Author(s):

Tim Vanbellingen ◽

Manuel Bertschi ◽

Thomas Nyffeler ◽

Dario Cazzoli ◽

Roland Wiest ◽

...

Keyword(s):

Parietal Cortex ◽

Posterior Parietal Cortex ◽

Theta Burst Stimulation ◽

Burst Stimulation ◽

Left Posterior ◽

Posterior Parietal ◽

Theta Burst

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Behavioral effects of continuous theta-burst stimulation in macaque parietal cortex

Scientific Reports ◽

10.1038/s41598-021-83904-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Lara Merken ◽

Marco Davare ◽

Peter Janssen ◽

Maria C. Romero

Keyword(s):

Parietal Cortex ◽

High Intensity ◽

Theta Burst Stimulation ◽

Burst Stimulation ◽

Primate Model ◽

Power Grip ◽

Fitts Law ◽

Behavioral Evidence ◽

Theta Burst ◽

Continuous Theta Burst Stimulation

AbstractThe neural mechanisms underlying the effects of continuous Theta-Burst Stimulation (cTBS) in humans are poorly understood. Animal studies can clarify the effects of cTBS on individual neurons, but behavioral evidence is necessary to demonstrate the validity of the animal model. We investigated the behavioral effect of cTBS applied over parietal cortex in rhesus monkeys performing a visually-guided grasping task with two differently sized objects, which required either a power grip or a pad-to-side grip. We used Fitts’ law, predicting shorter grasping times (GT) for large compared to small objects, to investigate cTBS effects on two different grip types. cTBS induced long-lasting object-specific and dose-dependent changes in GT that remained present for up to two hours. High-intensity cTBS increased GTs for a power grip, but shortened GTs for a pad-to-side grip. Thus, high-intensity stimulation strongly reduced the natural GT difference between objects (i.e. the Fitts’ law effect). In contrast, low-intensity cTBS induced the opposite effects on GT. Modifying the coil orientation from the standard 45-degree to a 30-degree angle induced opposite cTBS effects on GT. These findings represent behavioral evidence for the validity of the nonhuman primate model to study the neural underpinnings of non-invasive brain stimulation.

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