Theta Burst Transcranial Magnetic Stimulation Research Articles

0332 Improving Sleep with Continuous Theta Burst Transcranial Magnetic Stimulation (TMS) of the Default Mode Network

Abstract Introduction Chronic insomnia is a disorder associated with increased cognitive arousal. Insomnia is also associated with activation/connectivity within the default mode network (DMN) of the brain, consistent with the hyperarousal theory. We hypothesized that suppression of the DMN with a type of repetitive transcranial magnetic stimulation (rTMS) known as continuous theta burst stimulation (cTBS) would lead to improved overnight sleep. Methods Twenty participants (12 female; age=26.9, SD=6.6 years) meeting criteria for insomnia/sleep disorder completed a counterbalanced sham-controlled crossover study in which they served as their own controls on two separate nights of in-laboratory polysomnography (PSG) monitored sleep. In-lab visits occurred on separate weeks at least 5 days apart. Sessions included two resting state functional magnetic resonance imaging (fMRI) sessions separated by a brief 40 second cTBS rTMS session applied over an easily accessible cortical surface node of the DMN located at the left inferior parietal lobe. After scanning/stimulation, participants were allowed an 8-hour sleep opportunity from 2300 to 0700 monitored with PSG. Results One session of active cTBS significantly altered functional connectivity (p<.05, FDR corrected) within the DMN, while the sham condition produced no changes in functional connectivity from pre- to post-treatment. After controlling for age and IQ, active treatment was associated with significant (p<.05) improvements in PSG measured Total Sleep Time (TST; ηp2=.28), latency to Slow Wave Sleep (SWS; ηp2=.23), Sleep Efficiency (SE; ηp2=.28), and a lower Arousal Index (ηp2=.22). Overall, individuals obtained 16 minutes more sleep after active cTBS compared to sham. Moreover, changes in brain connectivity following cTBS significantly (p<.05) predicted sleep outcomes, including TST, sleep latency, SE, minutes of wake, SWS, number of awakenings, arousals, and arousal index, and a trend toward increased REM (p=.06). Conclusion A brief targeted 40-second stimulation with cTBS altered DMN brain functioning, and improved PSG measured sleep outcomes during the night following stimulation. The effect sizes often exceeded those reported for other established treatments such as cognitive behavioral therapy for insomnia or hypnotic sleep medications. Further work involving multiple stimulations over several days or weeks will be necessary to demonstrate the potential utility of this approach as a treatment for insomnia. Support (if any) W81XWH2010173

0066 Continuous Theta Burst Transcranial Magnetic Stimulation for Insomnia and its Effects on Verbal Recall Performance

Abstract Introduction In this project, we studied the efficacy of focused inhibitory stimulation using continuous theta burst stimulation (cTBS) repetitive transcranial magnetic stimulation (rTMS) on an easily accessible region of the default mode network (DMN). As reported elsewhere, we found that cTBS improved brain connectivity and objectively measured sleep. However, there is little known about the side effects of rTMS in the treatment of insomnia, so here we evaluated the effects on verbal memory recall. Methods Twenty adults with clinical insomnia completed this study (Mage=26.90, SD=6.56). Participants conducted two overnight visits during the study; one where they received active cTBS and one where they received a sham cTBS prior to sleep. Participants completed the California Verbal Learning Test (CVLT) before stimulation and again completed the recall portion following a night of laboratory monitored sleep. We analyzed CVLT recall performance with a repeated measures ANOVA with factors of condition (active cTBS vs. sham cTBS) and session (Short Recall, Long Recall, Cued Recall, and Recognition). Results Contrary to our hypothesis, our analyses indicate there was no significant effects on recall performance due to active cTBS. There was no main effect of condition on recall scores post-TMS administration (F(1, 18)=1.162, p=.220, ηp2 = 0.082). There was no interaction effect of active or sham cTBS on recall performance (F(4, 15)=.828, p=.528, ηp2=0.181). Posthoc pairwise comparisons demonstrated that there was no significant difference post-TMS administration between active cTBS and sham cTBS conditions on long recall, cued recall, or recognition (p>.05). There was no significant difference post-TMS administration on short-term recall performance. Participants scored lower on short term recall after receiving active cTBS (M=12.632; SD=2.910) than after sham cTBS administration (M=13.42 ;SD=2.545) (p=.048). Conclusion Compared to sham, active cTBS was not associated with any significant difference in long-term recall performance after TMS administration. While the results demonstrate there are short term effects to recall after administration, recall scores bounce back shortly after. While participants didn’t necessarily improve with active cTBS, it is beneficial to know there are no long-term harmful effects of active cTBS on recall as side effect of insomnia treatment. Support (if any) W81XWH2010173

0186 Continuous Theta Burst Transcranial Magnetic Stimulation and Signal Detection Performance on a Military Go/No-Go Task

Abstract Introduction Repetitive transcranial Magnetic Stimulation (rTMS) is an emerging non-pharmacological treatment method utilized to treat multiple clinical diagnoses to include anxiety, depression, and now insomnia. As part of a larger project, we showed that a single rTMS stimulation with continuous theta burst stimulation (cTBS) to the default mode network (DMN) was associated with improved sleep. However, there is little known about potential effects on attention and vigilance because of cTBS to the DMN. We hypothesized that active cTBS would have no significant impact on signal detection tasks post-TMS administration. Methods Twenty adults with clinical insomnia completed this study (Mage=26.90, SD=6.56). Participants completed two overnight visits in total; one where they received active cTBS and one where they received sham cTBS over an easily accessible node of the DMN (left angular gyrus). We analyzed signal detection performance utilizing a Go-No-Go (GNG) task. Three variables were calculated as a result: hit rate, correct rejection rate, and false alarm rate. Higher scores on hit rate and correct rejection rate indicate higher correct responses. Higher scores on false alarm rate indicates a higher number of incorrect responses. We conducted a repeated measures ANOVA with factors of condition, administration, and reversal. Results There was no main effect of condition on GNG hit rate (F(1,17)=1.365, p=.259, ηp2 =.074), GNG false alarm rate (F(1,17)=.210, p=.091, ηp2 =.244), or GNG correct rejection rate (F(1, 17)=1.677, p=.213, ηp2 =.090). We also found there were no significant interaction effects of TMS condition on performance on reversal conditions for GNG hit rate (F(1,17)=0.45, p=.834, ηp2 =.003), GNG false alarm rate (F(1,17)=1.572, p=.227, ηp2 =.085), or GNG correct rejection rate (F(1, 17)=1.510, p=.236, ηp2 =.082). Posthoc pairwise comparisons demonstrated that participants did not significantly differ on GNG hit rate, false alarm rate, or correct rejection rate between their active cTBS and sham cTBS session (p>.05). Conclusion Active cTBS was not significantly associated with any decline in response inhibition or signal detection. It is helpful for future recipients to know they are not adversely affected in attention or vigilance after receiving cTBS rTMS of the DMN for treatment of insomnia. Support (if any) W81XWH2010173

0063 Slow-wave Sleep Onset Latency Mediates Improvements in Attention and Processing Speed Following Continuous Theta-Burst (cTBS) TMS

Abstract Introduction Insomnia causes substantial health-care cost burden and is a risk factor for neurocognitive impairment. Increased DMN activity has been implicated in the hyperarousal theory of insomnia. In this pilot clinical trial, DMN was targeted via the left inferior parietal lobe using a brief 40 second cTBS Transcranial Magnetic Stimulation (rTMS). We hypothesized that neurocognitive improvements due to cTBS would be mediated by polysomnographic (PSG) parameters of slow wave sleep. Methods Twenty participants (12 female; age=26.9, SD=6.6 years) meeting criteria for insomnia completed a counterbalanced sham-controlled crossover design in which they served as their own controls on two separate nights of in-laboratory assessments. Sessions for both conditions included neurocognitive assessments at baseline, after stimulation (cTBS/sham) before bed, and the following morning. After stimulation, participants were allowed an 8-hour sleep opportunity from 2300 to 0700 monitored with PSG. The symbol coding and digit span subtests of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) exam are the main assessments in the current investigation. Results Improvements in attention and processing speed were observed after a night of sleep following both active TMS (cTBS; B = 11.05, p < .001) and sham TMS conditions (B = 8.10, p = .002) the prior day. In the cTBS condition only, these improvements in attention were mediated by latency to slow wave sleep (N3), such that shorter latencies were related to greater improvements on a simple attention task (RBANS digit span; B = -0.75, p < .001). This effect of night to morning improvement in attention and processing speed was also found in the sham condition for the coding task (B = 60.81, p < .001), but not for digit span. No effects of slow wave sleep duration on RBANS coding or digit span were observed in either condition. Conclusion Improvements in simple attention performance in response to cTBS may be, in part, due to slow wave sleep parameters. Moreover, results suggest that simple attention may have been more sensitive to the effects of cTBS, whereas processing speed may have been a factor of lower slow wave sleep onset latency. Support (if any) DoD PRMRPD W81XWH2010173

3. Adjunctive D-Cycloserine With Intermittent Theta-Burst Transcranial Magnetic Stimulation Improves Suicidal Ideation and Implicit Suicide Risk in Major Depressive Disorder

3. Adjunctive D-Cycloserine With Intermittent Theta-Burst Transcranial Magnetic Stimulation Improves Suicidal Ideation and Implicit Suicide Risk in Major Depressive Disorder

Efficacy of two intensive and spaced protocols of theta burst transcranial magnetic stimulation in treatment-resistant depression: a double-blind randomized trial

IntroductionDepression is the disease with the greatest burden of disability. Despite pharmacological options, up to 30% of depressions are considered resistant to treatment (RTD). Theta burst transcranial magnetic stimulation (TBS) on the dorsolateral prefrontal cortex allows the application of shorter protocols and with longer-lasting effects than conventional TMS. Its implementation in the Public Health System requires the design of efficient, cost-effective and accessible protocols for patients.ObjectivesThe objective of this project is to assess the efficacy and safety of two intensive and spaced protocols (unilateral and bilateral) of 1800 pulses TBS compared to sham stimulation in outpatients with unipolar and bipolar TRD in a public hospital.MethodsThis project is the 1st double-blind placebo-controlled RCT with TBS in Spain. It is now in the recruitment phase. Patients receive a total of 22 sessions of 1800 pulses in 6 weeks: 5 days/week the 1st and 2nd weeks (10 sessions) and 3 sessions/week the following weeks (12 sessions). Patients are randomized into three groups: i) bilateral, ii) left unilateral, and iii) sham. The main variable is the change in the HDRS-17 score at the end of treatment compared to baseline. The results were analyzed with a general linear model of HDRS, using time as the intrasubject factor and randomization group as the intersubject factor, using resistance to treatment (Maudsley Score) and diagnosis (bipolar, unipolar) as covariates.ResultsPreliminary results from 13 participants (nbil=4, nuni=4, nsham=5) reveal a significant effect of (group x time) on HDRS change (p= 0.020) with no influence of Maudsley Score or diagnosis. The bilateral group presented a greater decrease in the HDRS with a mean difference of 4,38 points [CI95% 0,17-8,58), (p=0.043)] with respect to the unilateral group and a difference of 8.23 [CI95% 4,24-12,21)(p =0.001)] compared to the sham group.Table 1:Sample description. Data shown are means and standar deviations. In bold significant diferences p<0,05.Bilateral TBS(n=4)UnilateralTBS(n=4)ShamTBS(n=5)Age [M (SD)]55,50(5,80)48,50(16,86)56,40(5,86)Male: Female [n]0:42:23:2Depression:Bipolar disorder [n]3:13:14:1Length of depresive episode (months) [M (SD)]12,00(4,08)16,50(6,61)15,00(5,83)Current number of antidepressants [M (SD)]2,00(0,82)1,75(0,50)2,60(0,55)Maudsley score [M (SD)]7,00(1,82)8,75(1,5)7,90(1,30)Basal HDRS basal [M (SD)]16,00(1,82)19,75(4,03)20,40(3,21)Final HDRS [M (SD)]5,75(3,30)10,75(3,10)17,80(2,49)Response /Remission[n (%)]3:3 (75%)2:0(50:0%)0:0 (0%)Image:ConclusionsThe results demonstrate the preliminary efficacy of intensive TBS protocols relative to sham.Disclosure of InterestNone Declared

Hitting the Target of Image-Guided Psychiatry?

Hitting the Target of Image-Guided Psychiatry?

Editor's Roundup for Issue 1 of 2023: Risk of Motor Vehicle Accident and Electroconvulsive Therapy, Effect of Electroconvulsive Therapy Electrode Placement on Risk for Asystole, Role of Maintenance Electroconvulsive Therapy in Reducing the Risk of Relapse, Long-term Tolerability of Vagus Nerve Stimulation, and Effect of Intensive Theta Burst Transcranial Magnetic Stimulation in Bipolar Depression.

From the Department of Psychiatry and Health Behavior, Medical College of Georgia, Augusta, GA. Received for publication November 19, 2022; accepted November 23, 2022. Reprints: William V. McCall, MD, MS, Department of Psychiatry and Health Behavior, Medical College of Georgia, 997 St Sebastian Way, Augusta, GA 30912 (e-mail: [email protected]). Dr McCall receives royalties from Wolters Kluwer and is a scientific advisor for Idorsia. He is also an advisor to Ingenio. The author has no conflict of interest or financial disclosures to report.

Accelerated intermittent theta burst transcranial magnetic stimulation is a safe and efficacious treatment for adolescents with depressive symptoms

Abstract Background: Intermittent theta burst stimulation (iTBS) has been shown to be a safe and effective therapy for depression in adult populations and more recently, newer protocols of accelerated transcranial magnetic stimulation (TMS) have become popularized due to the fast-acting effects. Previous literature has shown that iTBS in adolescents is safe and that TMS may be more effective in younger individuals, but it has yet to be explored in great detail with accelerated protocols. Methods: This case series describes three patients seen in the context of an outpatient clinic setting at Acacia Mental Health. The patients were treated for depressive symptoms which were confirmed by a staff psychiatrist. Self-reported mood surveys as assessed by the patient health questionnaire-9 (PHQ-9), were administered pre-treatment and post-treatment. The accelerated TMS treatment protocol administered to these patients varied in the brain region(s) targeted, TMS machine output intensity, protocol laterality, number of sessions per day, and total number of sessions. The TMS treatments were delivered via a MagVenture MagPro R30 system (MagVenture A/S, Denmark) equipped with a MagVenture Cool-B65 A/P coil. Results: All three cases were prescribed distinct accelerated protocols; two achieved self-reported remission and one achieved response as measured by the PHQ-9. All patients tolerated accelerated iTBS sessions without significant adverse events, demonstrating that this is a safe and effective treatment for adolescents with MDD. Conclusion: In these adolescent patients, accelerated TMS protocols were tolerated and showed meaningful clinical effects. These cases support rationale for future clinical applications of accelerated TMS in adolescent populations. Future studies should examine larger cohorts to gain a deeper understanding of accelerated TMS safety and efficacy in adolescents. Research Category and Technology and Methods Clinical Research: 10. Transcranial Magnetic Stimulation (TMS) Keywords: Transcranial Magnetic Stimulation, Theta Burst, Adolescence, Depression

Adrenomedullary responses to non-invasive cortical stimulation in humans

Abstract Introduction: The discovery of cortical adrenomedullary projections in cebus monkeys suggests that similar pathways exist in humans. Notably, the major corticoadrenomedullary projection regions have human equivalents that can be stimulated non-invasively with repetitive transcranial magnetic stimulation (rTMS). If rTMS can be used to selectively modulate adrenomedullary activity, there may be significant therapeutic benefits for stress-, affective-, or neuroimmune-related disorders. Purpose: To assess resting and stress-induced adrenomedullary neuroendocrine responses to continuous (cTBS) and intermittent (iTBS) theta burst TMS in humans. Methods: 39 healthy young adults (14W) were randomly assigned to three counterbalanced sessions of iTBS (n=19) or cTBS (n=20). Stimulation was applied to motor cortical areas that contain the majority of adrenomedullary projections in non-human primates (primary motor cortex trunk region (M1TRUNK) and presupplementary motor area (preSMA)). The M1 leg region (M1LEG) was used as a spatial control. Stimulation locations were determined based on TMS-evoked electromyographic responses in the rectus abdominus (M1TRUNK) and vastus lateralis (M1LEG) or using a combination of fMRI activity and metanalytical structural coordinates (preSMA). All TMS procedures were performed with a 96mm curved double coil and stereotactic navigation. TBS was applied as 600 biphasic TMS pulses at 80% AMT. Corticoadrenomedullary activity and corticospinal excitability (CSE) were assayed before and after TBS, immediately after maximal exercise, and 60min and 90min after TBS based on plasma epinephrine concentrations and median MEP AUC, respectively. Initial analysis of adrenomedullary responses to rTMS were made with a 2 (protocol) x 3 (visit) x 5 (time-point) mixed methods ANOVA. Results and Conclusions: As expected, exercise resulted in a large epinephrine increase (p<0.0001, 8-fold) overall. Ongoing analysis indicates that target-specific changes in adrenomedullary activity are likely, and similar to CSE, may often be paradoxical. Our preliminary results also suggest that adrenomedullary responses to subthreshold rTMS are principally stress inducible. Research Category and Technology and Methods Translational Research: 10. Transcranial Magnetic Stimulation (TMS) Keywords: Adrenal Medulla, Cortex, Sympathetic Nervous System, Non-Invasive Brain Stimulation

Non-invasive Brain Stimulation and Prism Adaptation in Art Constructive Errors in Painting.

This study aimed to investigate the influence of neglect and the effect of prism adaptation (PA) combined with continuous Theta-burst transcranial magnetic stimulation (cTBS) on the art constructive errors in painting rehabilitation of stroke patients with neglect. Fourteen patients with neglect and art constructive errors in painting secondary to stroke were randomly assigned to the rehabilitation group and received PA combined with the inhibitory protocol of cTBS over the intact parietal cortex; the control group received PA combined with sham cTBS for two weeks in ten daily sessions. Patients were assessed for art constructive errors in painting in figure copying test (FCT), and coloring test (CT) before and after the intervention. Art constructive errors in painting were classified into omission, deformation, size, neglect of warm colors, and perseveration of errors. Neglect was evaluated using the line bisection task (LBT), figure copying test (FCT), and coloring test (CT). All patients showed a significant improvement in art constructive errors in painting (measured using the pattern of painting' errors in FCT and CT), and neglect (measured using LBT, FCT, and CT) (P<0.05). Omission, neglect of warm colors, and deformation were the most frequent errors. Neglect and rehabilitation influence the painting system in stroke patients. Both approaches improved art constructive errors in painting and neglect symptoms.

Theta-burst transcranial magnetic stimulation of bilateral dorsolateral prefrontal cortex in patient with long COVID: A case report

Theta-burst transcranial magnetic stimulation of bilateral dorsolateral prefrontal cortex in patient with long COVID: A case report

Neuronavigated 20hz theta burst TMS of the right orbitofrontal cortex in the treatment of obsessive compulsive disorder

Neuronavigated 20hz theta burst TMS of the right orbitofrontal cortex in the treatment of obsessive compulsive disorder

Finding synaptic couplings from a biophysical model of motor evoked potentials after theta-burst transcranial magnetic stimulation

Objective: We aimed to use measured input-output (IO) data to identify the best fitting model for motor evoked potentials.Methods: We analyzed existing IO data before and after intermittent and continuous theta-burst stimulation (iTBS & cTBS) from a small group of subjects (18 for each). We fitted individual synaptic couplings and sensitivity parameters using variations of a biophysical model. A best performing model was selected and analyzed.Results: cTBS gives a broad reduction in MEPs for amplitudes larger than resting motor threshold (RMT). Close to threshold, iTBS gives strong potentiation. The model captures individual IO curves. There is no change to the population average synaptic weights post TBS but the change in excitatory-to-excitatory synaptic coupling is strongly correlated with the experimental post-TBS response relative to baseline.Conclusions: The model describes population-averaged and individual IO curves, and their post-TBS change. Variation among individuals is accounted for with variation in synaptic couplings, and variation in sensitivity of neural response to stimulation.Significance: The best fitting model could be applied more broadly and validation studies could elucidate underlying biophysical meaning of parameters.

Intermittent theta burst transcranial magnetic stimulation induces hippocampal mossy fibre plasticity in male but not female mice.

Transcranial magnetic stimulation (TMS) induces electric fields that depolarise or hyperpolarise neurons. Intermittent theta burst stimulation (iTBS), a patterned form of TMS that is delivered at the theta frequency (~5Hz), induces neuroplasticity in the hippocampus, a brain region that is implicated in memory and learning. One form of plasticity that is unique to the hippocampus is adult neurogenesis; however, little is known about whether TMS or iTBS in particular affects newborn neurons. Here, we therefore applied repeated sessions of iTBS to male and female mice and measured the extent of adult neurogenesis and the morphological features of immature neurons. We found that repeated sessions of iTBS did not significantly increase the amount of neurogenesis or affect the gross dendritic morphology of new neurons, and there were no sex differences in neurogenesis rates or aspects of afferent morphology. In contrast, efferent properties of newborn neurons varied as a function of sex and stimulation. Chronic iTBS increased the size of mossy fibre terminals, which synapse onto Cornu Ammonis 3 (CA3) pyramidal neurons, but only in males. iTBS also increased the number of terminal-associated filopodia, putative synapses onto inhibitory interneurons but only in male mice. This efferent plasticity could result from a general trophic effect, or it could reflect accelerated maturation of immature neurons. Given the important role of mossy fibre synapses in hippocampal learning, our results identify a neurobiological effect of iTBS that might be associated with sex-specific changes in cognition.

Efficacy and Safety of Bilateral Sequential Theta Burst Transcranial Magnetic Stimulation in Bipolar Depression: Result From an Observational Study

The majority of functional impairment in bipolar disorder occurs during the depressed phase of illness, which is frequently resistant to established interventions. In attempting to meet the ongoing need for experimental treatments, transcranial magnetic stimulation (TMS) trials have had varying effects on bipolar depression. The variable efficacy of TMS for bipolar depression highlights an unmet need to define the most optimal TMS settings for the specific syndrome of bipolar depression, and suggests the need for augmented TMS paradigms.

Investigating the role of human frontal eye field in the pupil light reflex modulation by saccade planning and working memory.

The pupil constricts in response to an increase in global luminance level, commonly referred to as the pupil light reflex. Recent research has shown that these reflex responses are modulated by high-level cognition. There is larger pupil constriction evoked by a bright stimulus when the stimulus location spatially overlaps with the locus of attention, and these effects have been extended to saccade planning and working memory (here referred to as pupil local-luminance modulation). Although research in monkeys has further elucidated a central role of the frontal eye field (FEF) and superior colliculus in the pupil local-luminance modulation, their roles remain to be established in humans. Through applying continuous theta-burst transcranial magnetic stimulation over the right FEF (and vertex) to inhibit its activity, we investigated the role of the FEF in human pupil local-luminance responses. Pupil light reflex responses were transiently evoked by a bright patch stimulus presented during the delay period in the visual- and memory-delay tasks. In the visual-delay task, larger pupil constriction was observed when the patch location was spatially aligned with the target location in both stimulation conditions. More interestingly, after FEF stimulation, larger pupil constriction was obtained when the patch was presented in the contralateral, compared to the ipsilateral visual field of the stimulation. In contrast, FEF stimulation effects were absence in the memory-delay task. Linear mixed model results further found that stimulation condition, patch location consistency, and visual field significantly modulated observed pupil constriction responses. Together, our results constitute the first evidence of FEF modulation in human pupil local-luminance responses.

Hand choice is unaffected by high frequency continuous theta burst transcranial magnetic stimulation to the posterior parietal cortex.

The current study used a high frequency TMS protocol known as continuous theta burst stimulation (cTBS) to test a model of hand choice that relies on competing interactions between the hemispheres of the posterior parietal cortex. Based on the assumption that cTBS reduces cortical excitability, the model predicts a significant decrease in the likelihood of selecting the hand contralateral to stimulation. An established behavioural paradigm was used to estimate hand choice in each individual, and these measures were compared across three stimulation conditions: cTBS to the left posterior parietal cortex, cTBS to the right posterior parietal cortex, or sham cTBS. Our results provide no supporting evidence for the interhemispheric competition model. We find no effects of cTBS on hand choice, independent of whether the left or right posterior parietal cortex was stimulated. Our results are nonetheless of value as a point of comparison against prior brain stimulation findings that, in contrast, provide evidence for a causal role for the posterior parietal cortex in hand choice.

Dorsolateral prefrontal cortex plays causal role in probability weighting during risky choice

In this study, we provide causal evidence that the dorsolateral prefrontal cortex (DLPFC) supports the computation of subjective value in choices under risk via its involvement in probability weighting. Following offline continuous theta-burst transcranial magnetic stimulation (cTBS) of the DLPFC subjects (N = 30, mean age 23.6, 56% females) completed a computerized task consisting of 96 binary lottery choice questions presented in random order. Using the hierarchical Bayesian modeling approach, we then estimated the structural parameters of risk preferences (the degree of risk aversion and the curvature of the probability weighting function) and analyzed the obtained posterior distributions to determine the effect of stimulation on model parameters. On a behavioral level, temporary downregulation of the left DLPFC excitability through cTBS decreased the likelihood of choosing an option with higher expected reward while the probability of choosing a riskier lottery did not significantly change. Modeling the stimulation effects on risk preference parameters showed anecdotal evidence as assessed by Bayes factors that probability weighting parameter increased after the left DLPFC TMS compared to sham.

Neural effects of continuous theta-burst stimulation in macaque parietal neurons.

Theta-burst transcranial magnetic stimulation (TBS) has become a standard non-invasive technique to induce offline changes in cortical excitability in human volunteers. Yet, TBS suffers from a high variability across subjects. A better knowledge about how TBS affects neural activity in vivo could uncover its mechanisms of action and ultimately allow its mainstream use in basic science and clinical applications. To address this issue, we applied continuous TBS (cTBS, 300 pulses) in awake behaving rhesus monkeys and quantified its after-effects on neuronal activity. Overall, we observed a pronounced, long-lasting, and highly reproducible reduction in neuronal excitability after cTBS in individual parietal neurons, with some neurons also exhibiting periods of hyperexcitability during the recovery phase. These results provide the first experimental evidence of the effects of cTBS on single neurons in awake behaving monkeys, shedding new light on the reasons underlying cTBS variability.