Background: Prefrontal abnormalities in schizophrenia have consistently emerged from resting state and cognitive neuroimaging studies. However, these correlative findings require causal verification via combined imaging/stimulation approaches. To date, no interleaved transcranial magnetic stimulation and functional magnetic resonance imaging study (TMS fMRI) has probed putative prefrontal cortex abnormalities in schizophrenia. Objective: /Hypothesis: We hypothesized that subjects with schizophrenia would show significant hyperexcitability at the site of stimulation (BA9) and decreased interhemispheric functional connectivity. Methods: We enrolled 19 unmedicated subjects with schizophrenia and 22 controls. All subjects underwent brain imaging using a 3T MRI scanner with a SENSE coil. They also underwent a single TMS fMRI session involving motor threshold (rMT) determination, structural imaging, and a parametric TMS fMRI protocol with 10 Hz triplet pulses at 0, 80, 100 and 120% rMT. Scanning involved a surface MR coil optimized for bilateral prefrontal cortex image acquisition. Results: Of the original 41 enrolled subjects, 8 subjects with schizophrenia and 11 controls met full criteria for final data analyses. At equal TMS intensity, subjects with schizophrenia showed hyperexcitability in left BA9 (p = 0.0157; max z-score = 4.7) and neighboring BA46 (p = 0.019; max z-score = 4.47). Controls showed more contralateral functional connectivity between left BA9 and right BA9 through increased activation in right BA9 (p = 0.02; max z-score = 3.4). GM density in subjects with schizophrenia positively correlated with normalized prefrontal to motor cortex ratio of the corresponding distance from skull to cortex ratio (S-BA9/S-MC) (r = 0.83, p = 0.004). Conclusions: Subjects with schizophrenia showed hyperexcitability in left BA9 and impaired interhemispheric functional connectivity compared to controls. Interleaved TMS fMRI is a promising tool to investigate prefrontal dysfunction in schizophrenia.

The and a of In Narcolepsy: CONTRAINDICATIONS: Advanced arteriosclerosis, symptomatic cardiovascular disease, moderate to severe hypertension, hyperthyroidism, known hypersensitivity or idiosyncrasy to the sympathomimetic amines, glaucoma. most indicated for ADHD, the possibility of growth suppression and the potential for precipitating motor tics and Tourette's exist with ADDERALL treatment and, rare cases, exacerbations of psychosis have been reported. may part overall for with close

Applying a precisely timed pulse of transcranial magnetic stimulation (TMS) over the right posterior parietal cortex (PPC) can produce temporary visuo-spatial neglect-like effects. Although the TMS is applied over PPC, it is not clear what other brain regions are involved. We applied TMS within a functional magnetic resonance imaging (fMRI) scanner to investigate brain activity during TMS induction of neglect-like bias in three healthy volunteers, while they performed a line bisection judgment task (i.e., the landmark task). Single-pulse TMS at 115% of motor threshold was applied 150 ms after the visual stimulus onset. Participants completed two different TMS/fMRI sessions while performing this task: one session while single-pulse TMS was intermittently and time-locked applied to the right PPC and a control session with TMS positioned over the vertex. Perceptual rightward bias was observed when TMS was delivered over the right PPC. During neglect-like behavior, the fMRI maps showed decreased neural activity within parieto-frontal areas, which are often lesioned or dysfunctional in patients with left neglect. Vertex TMS induced behavioral effects compatible with leftward response bias and increased BOLD signal in the left caudate (a site which has been linked to response bias). These results are discussed in relation to recent findings on neural networks subserving attention in space.

Objective: Clinically normal hand movement with altered cerebral activation patterns in cervical dystonia (CD) may imply cerebral adaptation. Since impaired sensorimotor integration appears to play a role in dystonia, left superior parietal cortex modulation with repetitive transcranial magnetic stimulation (TMS) was employed to further challenge adaptation mechanisms reflected by changes in cerebral activation.Methods: Seven CD patients and ten healthy controls were scanned on a 3T magnetic resonance imaging (MRI) scanner with 1 Hz inhibitory interleaved TMS. They executed and imagined right wrist flexion/extension movements. Each task was preceded by a 10-s period with or without TMS.Results: The activations of both tasks after TMS in controls showed a similar pattern as found in CD without TMS, i.e. activation increases in bilateral prefrontal and posterior parietal regions during both tasks and decreases in right anterior parietal cortex during imagery (P<0.001). the activations of both tasks after TMS in CD were weaker but with a similar trend in activation changes. Only in the right angular gyrus, TMS significantly failed to induce an activation increase in CD as was seen in the controls (P<0.001).Conclusion: The similarity between TMS effects on the distribution of cerebral activations in controls and the pattern seen in CD may support the concept that CD make use of compensatory circuitry enabling clinically normal hand movement. The fact that a similar but weaker TMS effect occurred in CD could suggest that the capacity of compensation is reduced. Particularly for the right angular gyrus, this reduction was statistically significant. (C) 2012 Elsevier B.V. All rights reserved.

The purpose of this study was to use interleaved transcranial magnetic stimulation/functional magnetic resonance imaging (TMS/fMRI) to investigate the effects of lamotrigine (LTG) and valproic acid (VPA) on effective connectivity within motor and corticolimbic circuits. In this randomized, double-blind, crossover trial, 30 healthy volunteers received either drug or placebo 3.5h prior to interleaved TMS/fMRI. We utilized dynamic causal modeling (DCM) to assess changes in the endogenous effective connectivity of bidirectional networks in the motor–sensory system and corticolimbic circuit. Results indicate that both LTG and VPA have network-specific effects. When TMS was applied over the motor cortex, both LTG and VPA reduced TMS-specific effective connectivity between primary motor (M1) and pre-motor cortex (PMd), and between M1 and the supplementary area motor (SMA). When TMS was applied over prefrontal cortex, however, LTG alone increased TMS-specific effective connectivity between the left dorsolateral prefrontal cortex (DLPFC) and the anterior cingulate cortex (ACC). In summary, LTG and VPA both inhibited effective connectivity in motor circuits, but LTG alone increased effective connectivity in prefrontal circuits. These results suggest that interleaved TMS/fMRI can assess region- and circuit-specific effects of medications or interventions.

In the article ‘‘Safety and Benefits of Distance-Adjusted Prefrontal Transcranial Magnetic Stimulation in Depressed Patients 55–75 Years of Age: A Pilot Study,’’ from Nahas et al., published in Depression and Anxiety 19:249–256 (2004), we found an error concerning Bohning’s formula that should be changed. Thus, on page 252: ‘‘We used the following formula to adjust the dose: Delivered intensity (%MT) 5 MT (EXP( 0.36 dPC))/ (EXP( 0.36 dMC)), where dPC is the measured MRI distance (in mm) from the scalp to the prefrontal cortex, and dMC is the distance for motor cortex.’’ It should be changed to: ‘‘We used the following formula to adjust the dose: Delivered intensity (%MT) 5 MT (EXP(0.036 dPC))/ (EXP(0.036 dMC)), where dPC is the measured MRI distance (in mm) from the scalp to the prefrontal cortex, and dMC is the distance for motor cortex.’’ This means that: (1) The correct value for the coefficient is 0.036 if the distances are stated in millimeters. (2) Numerator and denominator must be inverted (by removing the minus signal) in order to increase %MT directly proportional to both dPC and dMC values, which also increases the greater the atrophy.

Rationale Combined transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) can be used to study anticonvulsant drugs. A previous study showed that lamotrigine (LTG) inhibited brain activation induced when TMS was applied over motor cortex, whereas it increased activation induced by TMS applied over prefrontal cortex. Objectives The present double-blind, placebo-controlled, crossover study in 30 healthy subjects again combined TMS and fMRI to test whether the effects seen previously with LTG would be confirmed and to compare these with a second anticonvulsant drug, valproic acid (VPA). Results Statistical parametric mapping analysis showed that both LTG and VPA, compared to placebo, inhibited TMS-induced activation of the motor cortex. In contrast, when TMS was applied over prefrontal cortex, LTG increased the activation of limbic regions, confirming previous results; VPA had no effect. Conclusion We conclude that LTG and VPA have similar inhibitory effects on motor circuits, but differing effects on the prefrontal corticolimbic system. The study demonstrates that a combination of TMS and fMRI techniques may be useful in the study of the effects of neuroactive drugs on specific brain circuits.

The left parietal cortex contributes to goal-directed hand movement. In this study, we targeted this region with transcranial magnetic stimulation (TMS) to assess the effects on a wider distributed circuitry related to motor control. Ten healthy subjects underwent 3 Tesla functional magnetic resonance imaging (fMRI) with interleaved TMS. They either executed or imagined right wrist flexion/extension movements, which was preceded by a 10-second period either with or without TMS. This was applied to the left superior parietal cortex in 10 stimuli of 1 Hz at 115% motor threshold intensity. TMS preceding the movement execution condition resulted in significantly increased activation in the bilateral prefrontal, right temporo-parietal and left posterior parietal cortices, when compared to movement without such intervention (P<0.001 voxel-level; P<0.05, volume corrected). Movement imagery after TMS showed significantly increased activation in the left medial prefrontal cortex, right lateral prefrontal cortex, left supramarginal gyrus and right occipital cortex, while a decrease was present in bilateral anterior parietal cortex (P<0.01 voxel-level; P<0.05 volume corrected). Activation changes after TMS of left superior parietal cortex thus appears to increase prefrontal and posterior parietal cortex activation, associated with a reduced function of the anterior parietal cortex, including S2. These changes are thought to reflect an impaired ability to estimate the proprioceptive consequences of movement during its preparation, which is compensated by the increased contribution of more remote parietal and prefrontal cortical regions.

In the last decade, combined transcranial magnetic stimulation (TMS)-neuroimaging studies have greatly stimulated research in the field of TMS and neuroimaging. Here, we review how TMS can be combined with various neuroimaging techniques to investigate human brain function. When applied during neuroimaging (online approach), TMS can be used to test how focal cortex stimulation acutely modifies the activity and connectivity in the stimulated neuronal circuits. TMS and neuroimaging can also be separated in time (offline approach). A conditioning session of repetitive TMS (rTMS) may be used to induce rapid reorganization in functional brain networks. The temporospatial patterns of TMS-induced reorganization can be subsequently mapped by using neuroimaging methods. Alternatively, neuroimaging may be performed first to localize brain areas that are involved in a given task. The temporospatial information obtained by neuroimaging can be used to define the optimal site and time point of stimulation in a subsequent experiment in which TMS is used to probe the functional contribution of the stimulated area to a specific task. In this review, we first address some general methodologic issues that need to be taken into account when using TMS in the context of neuroimaging. We then discuss the use of specific brain mapping techniques in conjunction with TMS. We emphasize that the various neuroimaging techniques offer complementary information and have different methodologic strengths and weaknesses.

The electrophysiology of transcranial magnetic stimulation (TMS) of motor cortex is not well understood. In this study, we investigate several structural parameters of the corticospinal tract and their relation to the TMS motor threshold (MT) in 17 subjects, with and without schizophrenia. We obtained structural and diffusion tensor MRI scans and measured the fractional anisotropy and principal diffusion direction for regions of interest in the corticospinal tract. We also measured the skull‐to‐cortex distance over the left motor region. The anterior–posterior trajectory of principle diffusion direction of the corticospinal tract and skull‐to‐cortex distance were both found to be highly correlated with MT, while fractional anisotropy, age and schizophrenia status were not. Two parameters—skull‐to‐cortex distance and the anterior component of the principle diffusion direction of the corticospinal tract as it passes the internal capsule—are highly predictive of MT in a linear regression model, and account for 82% of the variance observed ( R 2 = 0.82, F = 20.27, P < 0.0001) in measurements of MT. The corticospinal tract's anterior–posterior direction alone contributes 13% of the variance explained. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.