HF rTMS Research Articles

Effects of repetitive transcranial magnetic stimulation of the right inferior parietal lobe on the body image perception in anorexia nervosa: A pilot randomized controlled study.

Restrictive anorexia nervosa (AN) is associated with distorted perception of body shape, previously linked to hypoactivity and reduced excitability of the right inferior parietal lobe (rIPL). Here, we investigated the impact of high-frequency repetitive transcranial magnetic stimulation (HF rTMS) of the rIPL on body shape perception in patients with AN. Seventeen patients with AN (median [Q1_Q3] age, 35 [27_39] years; disease duration, 12 [6_18] years) were randomly assigned to receive real or sham HF (10Hz) rTMS of the rIPL over a period of 2weeks, comprising 10 sessions. The primary outcome measure was the Body Shape Questionnaire (BSQ). Secondary outcomes included eating disorder symptoms, body mass index, mood, anxiety, and safety. Data collection were done at baseline, post-rTMS, and at 2weeks and 3 months post-rTMS. Following both real and sham rTMS of the rIPL, no significant differences were observed in body shape perception or other parameters. Both real and sham rTMS interventions were deemed safe and well tolerated. Notably, serious adverse events were associated with the underlying eating and mood disorders, resulting in hospitalization for undernutrition (five patients) or suicidal attempts (two patients). This pilot study does not support the use of rTMS of the rIPL as an effective method for improving body shape perception in individuals with the restrictive form of AN. Further research is warranted to comprehensively explore both the clinical and neurophysiological effects of HF rTMS in this population.

Gender differences in the effect of rtms with the H7-coil on physical and social anhedonia in schizophrenia spectrum disorder; a randomized, sham-controlled trial

IntroductionStudies of differences in the incidence and severity of physical and social anhedonia between women and men diagnosed with schizophrenia spectrum disorder (SSD) are often inconsistent, and gender differences in treatment response have not been well studied. Hormonal factors, such as those related to the menstrual cycle, pregnancy or menopause, as well as social and cultural patterns and roles, may influence treatment response. The incidence of affective or stress-related psychiatric comorbidities may be gender-specific, which could also complicate the treatment of anhedonia and other negative symptoms of SSD. Finally, there is no evidence of sufficient quality on gender differences in the effects of rTMS, but the results are intriguing and point to the need for further research.ObjectivesTo investigate gender differences in the effect of rTMS with the H7-coil on physical and social anhedonia in patients diagnosed with SSD with dominant negative symptoms.MethodsWe conducted a randomized, sham-controlled trial during 2000-2023 in the population of patients diagnosed with SSD with primary negative symptoms defined as PANSS negative symptoms subscale score > 24, and PANSS positive symptoms subscale score < 20. The intervention was HF rTMS H7 coil (Brainsway Ltd. Jerusalem, Israel) once daily for 20 days applied to the prefrontal cortex (mPFC and ACC) at 100% motor threshold with a frequency of 18 Hz, and total of 39600 pulses. The outcomes were Physical and Social Anhedonia Scales (PAS, and SAS). We controlled for the large number of relevant covariates.ResultsWe randomized 49 men and 29 women of similar age. The effect on physical anhedonia was statistically significant in women (b = 9.04; p = 0.016), but not in men (b = 2.87; p = 0.272). The effect on social anhedonia was similar, but the difference was smaller (for men b = 3.71; p = 0.082; for women b = 5.42; p = 0.043). However, the Wald test showed no statistically significant differences between the beta coefficients for women and men.ConclusionsBased on this study, it is not possible to make valid and reliable conclusions about the existence of gender differences in the effects of rTMS treatment of anhedonia with the H7 coil. However, it is possible to claim that the treatment of anhedonia with this protocol is effective in women.Disclosure of InterestNone Declared

Increasing Physical Activity among Breast Cancer Survivors by Modulating Temporal Orientation with rTMS: Feasibility and Potential Efficacy.

Maintaining adequate amounts of physical activity is a critical component of survivorship care for women with breast cancer. Increased physical activity is associated with increases in well-being, quality of life, and longevity, but women with cancer face unique, cancer-related factors that might affect physical activity. Consistent with the Competing Neurobehavioral Decision Systems model of decision making, we proposed to decrease delay discounting and increase physical activity by stimulating the executive function system via high-frequency repetitive transcranial magnetic stimulation (HF rTMS) of the left dorsolateral prefrontal cortex (LDLPFC). This randomized, sham-controlled, double-blinded trial examined the feasibility and potential efficacy of this approach to increase physical activity in breast cancer survivors. We hypothesized that active rTMS would significantly increase the mean number of steps per day and decrease delay discounting. Participants (n = 30) were primarily middle-aged (M = 53.7, SD = 7.9) and white with a mean BMI and body mass indices below 40. Indicators of feasibility and limited efficacy testing were positive. Although repeated-measures ANOVA revealed no significant changes in delay discounting, generalized estimating equations (GEE) found that participants in the active condition increased their mean daily steps by 400 steps per day, while those in the sham condition decreased this by nearly 600 steps per day. These findings indicate that the continued investigation of HF rTMS for increasing physical activity among women with breast cancer is justified.

Seizure threshold manipulation in electroconvulsive therapy via repetitive transcranial magnetic stimulation. A novel way of augmentation?

IntroductionA high seizure threshold (ST) is an impeding factor in certain patients, potentially preventing a successful electroconvulsive therapy (ECT) treatment. Several pharmacological and non-pharmacological methods have been put forward to augment ECT in such patients, however, to this date, only a handful of case reports existed about the potential role of repetitive transcranial magnetic stimulation (rTMS), as an augmentation method. Objectivesand Methods: In this randomized, double-blinded, sham controlled study, we set out to test the hypothesis of whether the application of high frequency transcranial magnetic stimulation (HF rTMS) lowers the seizure threshold for electroconvulsive therapy and whether it has an effect on other aspects of ECT treatment, such as seizure duration (SD), efficacy and safety. Results46 patients treated for a major depressive episode, indicated for ECT, were recruited to this study. A significantly lower seizure threshold was observed in the experimental group during ECT titration, on average a decrease by 34.55%, from 34.23 mC to 22.4 mC, p < 0.001 (Wilcox test). We had not observed a significant effect of TMS stimulation before ECT on seizure duration or clinical outcome. Another potentially important observation of this study is that 4 patients in the experimental group developed transient symptoms of hypomania/mania, all of which were stabilized after the combined stimulation protocol was halted spontaneously within a week, without the need to administer mood stabilizers. ConclusionIt is likely that HF rTMS stimulation prior to ECT is a novel and simple way of reducing the ST, which is useful in certain groups of patients undergoing this important treatment modality.

Study the therapeutic role of transcranial magnetic stimulation in a sample of Egyptian patients with resistant obsessive-compulsive disorder

Background: Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder that affects approximately 2-3% of the world population. The first-line treatments are selective serotonin reuptake inhibitors and cognitive behavioral therapy. Despite that, approximately 40- 60% of patients remain treatment refractive. Aim of work: Evaluating the efficacy of different frequencies of repetitive transcranial magnetic stimulation (rTMS) applied over the right dorsolateral prefrontal cortex (DLPFC) as an adjunctive treatment for resistant OCD. Patient and Methods: Thirty patients with treatment resistant OCD were randomly assigned to 2 weeks either active LF (1 Hz, n=10), HF (10 Hz, n=10) with parameters (25-minute trains, 1,500 pulses/day at 100% of the resting motor threshold RMT, 5 sessions/week) or sham (n=10) (same HF parameters with coil tilting). OCD, anxiety and depressive symptoms were assessed using: Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Hamilton Anxiety Scale (HAM-A), Beck Depression Inventory (BDI) and Clinical Global Impression-Severity scale (CGI-S) before and immediately after sessions and 3 months later. Results: A repeated-measures analysis of variance (ANOVA) revealed a non-significant reduction in Y-BOCS scores in the active groups compared with the sham group after 2 weeks and 3 months later. Similarly, there was non-significant effect of time and time×group interaction on scores of (HAM-A) (CGI-S). While there was a significant effect of time and time×group interaction on scores of (BDI) after 2 weeks with active stimulation especially LF-rTMS not after 3 months. There were no reports of serious adverse effects following the active or sham rTMS treatments. Conclusion: Neither LF nor HF rTMS over the right DLPFC appeared to be superior to sham rTMS for relieving OCD and anxiety symptoms in patients with treatment-resistant OCD. However, rTMS has a role in improving depressive symptoms, especially with LF-rTMS. Further trials with larger sample sizes should be conducted to confirm the present findings.

ROLE OF REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION IN TREATMENT OF COGNITIVE MANIFESTATIONS IN PARKINSON'S DISEASE

Background: Parkinson’s disease (PD) is the second common neurodegenerative disease and still the pharmacological treatment facing many problemsas motor complication and ineffectiveness of this treatment for most of the nonmotor symptoms. Non invasive brain stimulation (NIBS) as a new adjunctive method for treating these problems, repetitive transcranial magnetic stimulation one of NIBS techniques used in previous studies but with less consistent resultsconcerning therapeutic effect on cognitivs symptoms of PD. Aim of the work: determine whether HF-rTMS targeting LtDLPFC has beneficial effect on cognitive functions of PD patients, and if this effect present could last for longer periods after one month follow up. Patients and Methods: this randomized single blind case-control clinical study included sixty patients with idiopathic parkinson’s disease (PD) from neurology clinic of Ain Shams University hospitals in Cairo, in the period between December 2014 till December 2018. Subjects were classified according to UKPD Society Brain BankClinical Diagnostic Criteria into active and sham groups. Both groups are assessed before, immediately after completing 6 sessions of rTMS and 4 weeks after the last session. Results: This study showed moderate significant improvement ofcognitive symptoms in PD patients of active group compared to Sham group, this improvement limited to the immediately after rTMS phase not maintained in the follow up. Correlations of improvement were minimal between T2 time scores of different scales. Conclusion: HF rTMS applied over left DLPFC showed short term immediate improvement of cognitive functions of PD patients but had no long lasting effects.

Combining HF rTMS over the Left DLPFC with Concurrent Cognitive Activity for the Offline Modulation of Working Memory in Healthy Volunteers: A Proof-of-Concept Study.

It has been proposed that the effectiveness of non-invasive brain stimulation (NIBS) as a cognitive enhancement technique may be enhanced by combining the stimulation with concurrent cognitive activity. However, the benefits of such a combination in comparison to protocols without ongoing cognitive activity have not yet been studied. In the present study, we investigate the effects of fMRI-guided high-frequency repetitive transcranial magnetic stimulation (HF rTMS) over the left dorsolateral prefrontal cortex (DLPFC) on working memory (WM) in healthy volunteers, using an n-back task with spatial and verbal stimuli and a spatial span task. In two combined protocols (TMS + WM + (maintenance) and TMS + WM + (rest)) trains of stimuli were applied in the maintenance and rest periods of the modified Sternberg task, respectively. We compared them to HF rTMS without a cognitive load (TMS + WM −) and control stimulation (TMS − WM + (maintenance)). No serious adverse effects appeared in this study. Among all protocols, significant effects on WM were shown only for the TMS + WM − with oppositely directed influences of this protocol on storage and manipulation in spatial WM. Moreover, there was a significant difference between the effects of TMS + WM − and TMS + WM + (maintenance), suggesting that simultaneous cognitive activity does not necessarily lead to an increase in TMS effects.

The effects of repetitive transcranial magnetic stimulation on body weight and food consumption in obese adults: A randomized controlled study

BackgroundAlthough some studies have reported significant reductions in food cravings following the single-session of repetitive transcranial magnetic stimulation (rTMS), there is little research on the effects of multi-session of rTMS on food consumption and body weight in obese subjects. ObjectiveWe conducted 4-week randomized, sham-controlled, single-blind, parallel-group trial to examine the effect of rTMS on body weight in obese adults. MethodsForty-three obese patients (body mass index [BMI] ≥25 kg/m2) aged between 18 and 70 years were randomized to the sham or real treatment group (21 in the TMS group and 22 in the sham treatment group). A total of 8 sessions of rTMS targeting the left dorsolateral prefrontal cortex (DLPFC) was provided over a period of 4 weeks. The primary outcome measure was weight change in kilograms from baseline to 4 weeks. Secondary endpoints included changes in anthropometric measures, cardiovascular risk factors, food intake, and appetite. ResultsParticipants in the rTMS group showed significantly greater weight loss from baseline following the 8 session of rTMS (−2.75 ± 2.37 kg vs. 0.38 ± 1.0 kg, p < 0.01). Consistent with weight loss, there was a significant reduction in fat mass and visceral adipose tissue at week 4 in the rTMS group compared with the control group (p < 0.01). After the 8 sessions of rTMS, the TMS group consumed fewer total kilocalories and carbohydrates per day than the control group (p < 0.05). Conclusions8 sessions of HF rTMS delivered to the left DLPFC were effective in inducing weight loss and decreasing food intake in obese patients. Trial registrationClinical trial registered with the Clinical Trials Registry at http://cris.cdc.go.kr (KCT0002548).

Clinical effects of high frequency repeated transcranial magnetic stimulation therapy on dyskinesia in patients with incomplete spinal cord injury:a Meta-analysis

To systematically evaluate the clinical effect of high frequency repeated transcranial magnetic stimulation(HF rTMS)therapy on dyskinesia in patients with incomplete spinal cord injury. Randomized controlled trials(RCTs) about HF rTMS therapy on patients with motor incomplete spinal cord injury were searched electronically in PubMed, Google scholar, Cochrane library, Clinical trial, Medline, Web of science, CNKI, VIP, and Wanfang database before October 2016. Two reviewers independently screened the literatures according to the inclusion and exclusion criteria, as well as extracted the data and assessed the methodological quality. The observed outcomes included ASIA motor score, ASIA lower extremities motor score(LEMS), Modified Ashworth score (MAS), Ten-meter walking test (10MWT) and Walking index for SCI II(WISCI II), and the outcomes were analyzed using RevMan5.2 software provided by the Cochrane information management system. Five RCTs involved 103 patients were included, and 61 patients(experimental group) accepted real rTMS and physical rehabilitation care for SCI, 51 patients(control group) accepted only physical rehabilitation care. There were significant differences in ASIA motor score, LEMS and 10MWT between two groups after HF rTMS therapy (statistics were Z=2.96, P=0.003; Z=3.04, P=0.002; Z=2.16, P=0.03; respectively). When stimulating the leg motor cortex, there was significant difference in MAS between two groups(Z=2.79, P=0.005), and when stimulating the vertex, there was no significant difference(Z=0.09, P=0.93). There was no significant difference in WISCI IIscore after HF rTMS therapy between two groups(Z=0.90, P=0.37). HF rTMS can raise motor score in patients with incomplete spinal cord injury, improve the spasticity of the lower extremities, and increase the motor ability.

Effectiveness of adjunctive repetitive transcranial magnetic stimulation in management of treatment-resistant depression: A retrospective analysis.

Background:There is limited number of studies from India investigating role of repetitive transcranial magnetic stimulation (rTMS) in treatment-resistant depression (TRD). This clinic-based study reports on the efficacy of rTMS as an add-on treatment in patients suffering from TRD.Materials and Methods:Twenty-two right-handed patients suffering from major depressive disorder who failed to respond to adequate trials of at least two antidepressants drugs in the current episode received rTMS as an augmenting treatment. High-frequency (Hf) rTMS at 110% of the estimated resting motor threshold (MT) was given over the left dorsolateral prefrontal cortex (DLPFC). A total of 15 sessions were given over 3 weeks with 3000 pulses per session. The outcome was assessed based on the changes in scores of Hamilton Rating Scale for Depression or Montgomery–Asberg Depression Rating Scale.Results:There was a significant reduction in final assessment scores after rTMS intervention as compared to baseline with almost 50% of the participants showing response in either scale.Conclusion:Hf rTMS applied over left DLPFC is an effective add-on treatment strategy in patients with TRD.

Transcranial Magnetic Stimulation to Address Mild Cognitive Impairment in the Elderly: A Randomized Controlled Study.

Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique with potential to improve memory. Mild cognitive impairment (MCI), which still lacks a specific therapy, is a clinical syndrome associated with increased risk of dementia. This study aims to assess the effects of high-frequency repetitive TMS (HF rTMS) on everyday memory of the elderly with MCI. We conducted a double-blinded randomized sham-controlled trial using rTMS over the left dorsolateral prefrontal cortex (DLPFC). Thirty-four elderly outpatients meeting Petersen's MCI criteria were randomly assigned to receive 10 sessions of either active TMS or sham, 10 Hz rTMS at 110% of motor threshold, 2,000 pulses per session. Neuropsychological assessment at baseline, after the last session (10th) and at one-month follow-up, was applied. ANOVA on the primary efficacy measure, the Rivermead Behavioural Memory Test, revealed a significant group-by-time interaction (p = 0.05), favoring the active group. The improvement was kept after one month. Other neuropsychological tests were heterogeneous. rTMS at 10 Hz enhanced everyday memory in elderly with MCI after 10 sessions. These findings suggest that rTMS might be effective as a therapy for MCI and probably a tool to delay deterioration.

Transcranial Magnetic Stimulation of the Left Dorsolateral Prefrontal Cortex Decreases Cue-induced Nicotine Craving and EEG Delta Power

BackgroundTMS has high potential as smoking cessation treatment. However, the neural mechanisms underlying TMS induced reduction of tobacco craving remain unclear. Electroencephalographic (EEG) delta frequency has been associated with the activity of the dopaminergic brain reward system, which is crucial for nicotine induced effects, and decreases after nicotine admission in smokers. ObjectiveThe aim of this study was to investigate EEG delta power changes induced by hf rTMS of the left dorsolateral prefrontal cortex (DLPFC) in nicotine deprived smokers and it's relation to cue-induced nicotine craving. MethodsFourteen healthy smokers meeting ICD-10 criteria for tobacco addiction participated in this within-subject sham controlled study. Participants had to abstain from smoking 6 h before the experiment. Effects of high-frequency repetitive TMS (hf rTMS) (10 Hz) for verum (left DLPFC) and sham (vertex) stimulations on cue-induced nicotine craving and resting state EEG delta power were assessed before and three times within 40 min after rTMS. ResultsBoth craving (P = 0.046) and EEG delta power (P = 0.048) were significantly lower after verum stimulation compared to sham stimulation across the whole post stimulation time period assessed. However, changes of craving ratings and delta power did not correlate. ConclusionHf rTMS applied to the left DLPFC reduces nicotine craving in short-term abstinent smokers. Changes in delta activity support the idea that stimulation induced effects are mediated by the dopaminergic brain reward system, which presumably plays a prominent, but probably not exclusive, role in this stimulation induced behavioral modulation, making this method a promising smoking cessation treatment candidate.

Neuromodulation of delay discounting, the reflection effect, and cigarette consumption

Cigarette smokers and substance users discount the value of delayed outcomes more steeply than non-users. Higher discounting rates are associated with relapse and poorer treatment outcomes. The left dorsolateral prefontal cortex (DLPFC) exerts an inhibitory influence on impulsive or seductive choices. Greater activity in the prefrontal cortex is associated with lower discounting rates. We hypothesized that increasing activity in the left DLPFC with high frequency repetitive transcranial magnetic stimulation (HF rTMS) would decrease delay discounting and decrease impulsive decision-making in a gambling task as well as decrease cigarette consumption, similar to other studies. In this single-blind, within-subjects design, smokers with no intention to quit (n=47) and nonsmokers (n=19) underwent three counterbalanced sessions of HF rTMS (20Hz, 10Hz, sham) delivered over the left DLPFC. Tasks were administered at baseline and after each stimulation session. Stimulation decreased discounting of monetary gains (F[3,250]=4.46, p<.01), but increased discounting of monetary losses (F[3,246]=4.30, p<.01), producing a reflection effect, normally absent in delay discounting. Stimulation had no effect on cigarette consumption. These findings provide new insights into cognitive processes involved with decision-making and cigarette consumption and suggest that like all medications for substance dependence, HF rTMS is likely to be most effective when paired with cognitive–behavioral interventions.

Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) during capsaicin-induced pain: modulatory effects on motor cortex excitability

Evidence by functional imaging studies suggests the role of left DLPFC in the inhibitory control of nociceptive transmission system. Pain exerts an inhibitory modulation on motor cortex, reducing MEP amplitude, while the effect of pain on motor intracortical excitability has not been studied so far. In the present study, we explored in healthy subjects the effect of capsaicin-induced pain and the modulatory influences of left DLPFC stimulation on motor corticospinal and intracortical excitability. Capsaicin was applied on the dorsal surface of the right hand, and measures of motor corticospinal excitability (test-MEP) and short intracortical inhibition (SICI) and facilitation (ICF) were obtained by paired-pulse TMS on left motor cortex. Evaluations were made before and at different times after capsaicin application in two separate sessions: without and with high-frequency rTMS of left DLPF cortex, delivered 10 min. after capsaicin application. We performed also two control experiments to explore: 1: the effects of Left DLPFC rTMS on capsaicin-induced pain; 2: the modulatory influence of left DLPFC rTMS on motor cortex without capsaicin application. Capsaicin-induced pain significantly reduced test MEP amplitude and decreased SICI leaving ICF unchanged. Left DLPFC rTMS, together with the analgesic effect, was able to revert the effects of capsaicin-induced pain on motor cortex restoring normal MEP and SICI levels. These data support the notion that that tonic pain exerts modulatory influence on motor intracortical excitability; the activation of left DLPFC by hf rTMS could have analgesic effects, reverting also the motor cortex excitability changes induced by pain stimulation.

Changes of blood lactate levels after repetitive transcranial magnetic stimulation

The objective was to study whether repetitive transcranial magnetic stimulation (rTMS) of the motor cortex could induce modification of peripheral blood lactate values. Nineteen young healthy volunteers were included; during the study, all subjects were at rest, sitting on a comfortable armchair. The muscular activation was evaluated by continuous electromyographic record. TMS was performed by using a circular coil at the vertex. Resting motor threshold (rMT) was defined as the lowest TMS intensity able to induce motor responses of an amplitude >50μV in the relaxed contralateral target muscle in approximately 50% of 20 consecutive stimuli. Venous blood lactate values were measured before, immediately after and 10min after a single session of low frequencies (1Hz for 15min) rTMS (LF rTMS) or high frequency (20Hz for 15min) rTMS (HF rTMS). As expected, LF rTMS induced a decrease of motor cortex excitability, whereas HF rTMS evoked an increase of motor cortex excitability. However, in the present investigation we observed that both conditions are associated to a significant increase of blood lactate. Since in our experimental conditions we can exclude a muscular production of lactate, the significant increment of peripheral blood lactate values, observed 10min after the end of the rTMS session, is probably due to the crossing by brain-produced lactate of the blood–brain barrier.

Motor intracortical inhibition in PD: L-DOPA modulation of high-frequency rTMS effects

Dopaminergic drugs and deep brain stimulation restore cortical inhibition in Parkinson disease (PD) patients. High-frequency rTMS was also found to increase cortical inhibition in PD but its therapeutic effect is still controversial. Here we hypothesize that, if dopaminergic drugs reverse to normal cortical excitability in M1, the effect of high-frequency (hf)-rTMS in PD patients could depend on whether they are in a medicated or unmedicated state. The present study aims to explore the lasting effects of sub-threshold hf rTMS trains over M1 on cortical inhibition in patients with "on" and without "off" L-DOPA treatment. Fourteen PD patients were examined twice while "on" and "off" medication. In both conditions, a paired-pulse paradigm was used to evaluate short intracortical inhibition (SICI) and long intracortical inhibition (LICI) that were evaluated before and after hf rTMS trains applied on the motor cortex. The results were compared with those obtained from normal controls. In baseline condition, SICI and LICI were significantly reduced in "off" compared to "on" patients and controls. hf-rTMS over the motor cortex significantly increased SICI and LICI in "off" medication PD patients. Magnetic stimulation proved to be ineffective when the same patients were in "on" state. The results showed that hf-rTMS affected intracortical inhibition (ICI) only in unmedicated patients. By restoring cortical inhibitory circuits dopaminergic drugs, normalize the excitability changes in M1 subsequent to motor rTMS. Whether patients are in a medicated or an unmedicated state would therefore appear to be critical for rTMS effects in PD patients. If a positive correlation exists between increased cortical inhibition and clinical improvement, hf-rTMS during the "off" state could be regarded as a potential add-on treatment to reduce the need of L-dopa and thus delay the adverse effects of its chronic use.

Opposite impact on 14C-2-deoxyglucose brain metabolism following patterns of high and low frequency repetitive transcranial magnetic stimulation in the posterior parietal cortex

Repetitive transcranial magnetic stimulation (rTMS) appears capable of modulating human cortical excitability beyond the duration of the stimulation train. However, the basis and extent of this "off-line" modulation remains unknown. In a group of anesthetized cats, we applied patterns of real or sham focal rTMS to the visuo-parietal cortex (VP) at high (HF) or low (LF) frequency and recorded brain glucose uptake during (on-line), immediately after (off-line), or 1 h after (late) stimulation. During the on-line period LF and HF rTMS induced a significant relative reduction of (14)C-2DG uptake in the stimulated VP cortex and tightly linked cortical and subcortical structures (e.g. the superficial superior colliculus, the pulvinar, and the LPl nucleus) with respect to homologue areas in the unstimulated hemisphere. During the off-line period HF rTMS induced a significant relative increase in (14)C-2DG uptake in the targeted VP cortex, whereas LF rTMS generated the opposite effect, with only mild network impact. Moderate distributed effects were only recorded after LF rTMS in the posterior thalamic structures. No long lasting cortical or subcortical effects were detected during the late period. Our findings demonstrate opposite modulation of rTMS on local and distant effects along a specific network, depending on the pattern of stimulation. Such effects are demonstrated in the anesthetized animal, ruling out behavioral and non-specific reasons for the differential impact of the stimulation. The findings are consistent with previous differential electrophysiological and behavioral effects of low and high frequency rTMS patterns and provide support to uses of rTMS in neuromodulation.