Background: Through transcranial magnetic stimulation (TMS) it is possible to change cortical excitability of the visual cortex, and to influence binocular balance. The main goal of our study is to assess the effect of transcranial magnetic stimulation, specifically theta burst stimulation (TBS), in a group of amblyopic volunteers measuring several visual parameters: visual acuity, suppressive imbalance, and stereoacuity. Methods: Thirteen volunteers aged 19 to 24 years, randomly split in 2 groups, underwent 1 session of continuous TBS, stimulating the right occipital lobe. The first group with 8 volunteers was exposed to active stimulation with cTBS, and the other group with 5 volunteers was exposed to placebo stimulation. Results: Significant improvements in visual acuity, suppressive imbalance, and stereoacuity were found in the amblyopic eye after cTBS. The average value of amblyopia in visual acuity before stimulation was 0.32 ± 0.20 logMar and after cTBS was 0.19 ± 0.17 logMar. The mean value for the control group before placebo stimulation was 0.28 ± 0.17 and after placebo stimulation was 0.28 ± 0.16. The suppressive imbalance in the group of amblyope subjects stimulated before cTBS was 0.26 ± 0.18 and after was 0.12 ± 0.12; the suppressive imbalance of the control group before the placebo stimulation was 0.34 ± 0.37 and after was 0.32 ± 0.40. Conclusions: Visual acuity, suppressive imbalance, and stereoacuity had significant enhancements compared with baseline after cTBS over the right occipital lobe in an ambliopic population.

After decades of effort, there are no effective clinical treatments to induce the recovery of ischemia-injured tissues, and among the several strategies that have been explored, repetitive transcranial magnetic stimulation has proven to be one of the most promising, with beneficial effects in limb motor function, aphasia, hemispatial neglect, or dysphagia. Despite the clinical evidences, little is known about the mechanisms underlying those effects. The present study aimed to explore the cellular and molecular effects of high-frequency repetitive magnetic stimulation (HF-rMS) on an in vitro model of ischemia. Using primary cortical cultures exposed to oxygen and glucose deprivation followed by reperfusion, we observed that HF-rMS treatment prevents the ischemia-induced neuronal death by 21.2%, and the neurite degeneration triggered by ischemia. Our results also demonstrate that with this treatment there is an increase of 89.2% on the number cells expressing ERK1/2, of 20.1% on the number of cells expressing c-Fos, and a synaptogenic effect, through an increase of 62.9% in the number of synaptic puncta as well as of 49.4% in their intensity. Interestingly, our results indicate that astrocytes are crucial to the beneficial effects triggered by HF-rMS after ischemia, thus suggesting a direct effect of HF-rMS on these cells. The modulation of astrocytes with this non-invasive brain stimulation technique is a promising approach to promote the recovery of ischemia-induced injured tissues; however, it is essential to understand how these effects can be modulated in order to optimize the protocols and enhance the beneficial outcomes.

Theta-burst stimulation (TBS) can be a non-invasive technique to modulate cognitive functions, with promising therapeutic potential, but with some contradictory results. Event related potentials are used as a marker of brain deterioration and can be used to evaluate TBS-related cognitive performance, but its use remains scant. This study aimed to study bilateral inhibitory and excitatory TBS effects upon neurocognitive performance of young healthy volunteers, using the auditory P300’ results. Using a double-blind sham-controlled study, 51 healthy volunteers were randomly assigned to five different groups, two submitted to either excitatory (iTBS) or inhibitory (cTBS) stimulation over the left dorsolateral pre-frontal cortex (DLPFC), two other actively stimulated the right DLPFC and finally a sham stimulation group. An oddball based auditory P300 was performed just before a single session of iTBS, cTBS or sham stimulation and repeated immediately after. P300 mean latency comparison between the pre- and post-TBS stimulation stages revealed significantly faster post stimulation latencies only when iTBS was performed on the left hemisphere (p = 0.003). Right and left hemisphere cTBS significantly delayed P300 latency (right p = 0.026; left p = 0.000). Multiple comparisons for N200 showed slower latencies after iTBS over the right hemisphere. No significant difference was found in amplitude variation. TBS appears to effectively influence neural networking involved in P300 formation, but effects seem distinct for iTBS vs cTBS and for the right or the left hemisphere. P300 evoked potentials can be an effective and practical tool to evaluate transcranial magnetic stimulation related outcomes.