scholarly journals Alertness fluctuations during task performance modulate cortical evoked responses to transcranial magnetic stimulation

2017 ◽  
Author(s):  
Valdas Noreika ◽  
Marc R. Kamke ◽  
Andrés Canales-Johnson ◽  
Srivas Chennu ◽  
Tristan A. Bekinschtein ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Cognitive Neuroscience ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Brain Activity ◽  
Single Pulse ◽  
Neural Recording ◽  
Neural Responses ◽  
Spontaneous Fluctuations

ABSTRACTTranscranial magnetic stimulation (TMS) has been widely used in human cognitive neuroscience to examine the causal role of distinct cortical areas in perceptual, cognitive and motor functions. However, it is widely acknowledged that the effects of focal cortical stimulation on behaviour can vary substantially between participants and even from trial to trial within individuals. Here we asked whether spontaneous fluctuations in alertness can account for the variability in behavioural and neurophysiological responses to TMS. We combined single-pulse TMS with neural recording via electroencephalography (EEG) to quantify changes in motor and cortical reactivity with fluctuating levels of alertness defined objectively on the basis of ongoing brain activity. We observed rapid, non-linear changes in TMS-evoked neural responses – specifically, motor evoked potentials and TMS-evoked cortical potentials – as EEG activity indicated decreasing levels of alertness, even while participants remained awake and responsive in the behavioural task.IMPACT STATEMENTA substantial proportion of inter-trial variability in neurophysiological responses to TMS is due to spontaneous fluctuations in alertness, which should be controlled for during experimental and clinical applications of TMS.

scholarly journals Disrupted Central Inhibition after Transcranial Magnetic Stimulation of Motor Cortex in Schizophrenia with Long-Term Antipsychotic Treatment

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Aulikki Ahlgrén-Rimpiläinen ◽  
Hannu Lauerma ◽  
Seppo Kähkönen ◽  
Ilpo Rimpiläinen
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Silent Period ◽  
Single Pulse ◽  
Contralateral Side ◽  
Antipsychotic Treatment ◽  
Stimulation Of

Aims. Schizophrenia is a neuropsychiatric disorder associated with mental and motor disturbances. We aimed to investigate motor control, especially central silent period (CSP) in subjects with schizophrenia (n=11) on long-term antipsychotic treatment compared to healthy controls (n=9). Methods. Latency and duration of motor evoked potentials (MEPs) and CSPs were measured with the help of single pulse transcranial magnetic stimulation (TMS) and intramuscular electrodes. After stimulation of the dominant and nondominant motor cortex of abductor digiti minimi (ADM) and tibialis anterior (TA) muscle areas, respective responses were measured on the contralateral side. Results. MEPs did not differ significantly between the groups. Multiple CSPs were found predominantly in subjects with schizophrenia, which showed a higher number of CSPs in the dominant ADM and the longest summarized duration of CSPs in the nondominant ADM (P<0.05) compared to controls. Conclusions. There were multiple CSPs predominantly in the upper extremities and in the dominant body side in subjects with schizophrenia. Behind multiple CSPs may lie an impaired regulation of excitatory or inhibitory neurotransmitter systems in central motor pathways. Further research is needed to clarify the role of the intramuscular recording methods and the effect of antipsychotics on the results.

Role of Sustained Excitability of the Leg Motor Cortex After Transcranial Magnetic Stimulation in Associative Plasticity

2007 ◽  
Vol 98 (2) ◽  
pp. 657-667 ◽  
Author(s):  
François D. Roy ◽  
Jonathan A. Norton ◽  
Monica A. Gorassini
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Cortical Neurons ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Low Frequency ◽  
Single Pulse ◽  
Common Peroneal Nerve ◽  
Lower Limbs ◽  
Sensory Inputs

Changes in the strength of corticospinal projections to muscles in the upper and lower limbs are induced in conscious humans after paired associative stimulation (PAS) to the motor cortex. We tested whether an intervention of PAS consisting of 90 low-frequency (0.1-Hz) stimuli to the common peroneal nerve combined with suprathreshold transcranial magnetic stimulation (TMS) produces specific changes to the motor-evoked potentials (MEPs) in lower leg muscles if the afferent volley from peripheral stimulation is timed to arrive at the motor cortex after TMS-induced firing of corticospinal neurons. Unlike PAS in the hand, MEP facilitation in the leg was produced when sensory inputs were estimated to arrive at the motor cortex over a range of 15 to 90 ms after cortical stimulation. We examined whether this broad range of facilitation occurred as a result of prolonged subthreshold excitability of the motor cortex after a single pulse of suprathreshold TMS so that coincident excitation from sensory inputs arriving many milliseconds after TMS can occur. We found that significant facilitation of MEP responses (>200%) occurred when the motor cortex was conditioned with suprathreshold TMS tens of milliseconds earlier. Likewise, it was possible to induce strong MEP facilitation (85% at 60 min) when afferent inputs were directly paired with subthreshold TMS. We argue that in the leg motor cortex, facilitation of MEP responses from PAS occurred over a large range of interstimulus intervals as a result of the paired activation of sensory inputs with sustained, subthreshold activity of cortical neurons that follow a pulse of suprathreshold TMS.

scholarly journals Response to Ruby et al: On a ‘failed’ attempt to manipulate conscious perception with transcranial magnetic stimulation to prefrontal cortex

2018 ◽  
Author(s):  
Anil Seth ◽  
Adam Barrett ◽  
David J Schwartzman ◽  
Daniel Bor
Keyword(s):  
Prefrontal Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Cognitive Neuroscience ◽  
Magnetic Stimulation ◽  
Signal Detection Theory ◽  
Good Practice ◽  
Initial Study ◽  
Good Evidence ◽  
Prefrontal Cortical

Does disruption of prefrontal cortical activity using transcranial magnetic stimulation (TMS) impair visual metacognition? An initial study supporting this idea (Rounis, Maniscalco, Rothwell, Passingham, &amp; Lau, 2010) motivated an attempted replication and extension (Bor, Schwartzman, Barrett, &amp; Seth, 2017). Bor et al. failed to replicate the initial study, concluding that there was not good evidence that TMS to prefrontal cortex impairs visual metacognition. This failed replication has recently been critiqued by some of the authors of the initial study (Ruby, Maniscalco, Lau, &amp; Peters, 2017). Here, we argue that these recent criticisms are misplaced. In responding to the criticisms of Ruby et al, we encounter some more general issues concerning good practice in replication of cognitive neuroscience studies, and in setting criteria for excluding data when employing statistical analyses like signal detection theory. We look forward to further studies of the role of prefrontal cortex in metacognition, with increasingly refined methodologies, motivated by the discussions in this series of papers.

scholarly journals Preserved Transcallosal Inhibition to Transcranial Magnetic Stimulation in Nondemented Elderly Patients with Leukoaraiosis

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Giuseppe Lanza ◽  
Rita Bella ◽  
Salvatore Giuffrida ◽  
Mariagiovanna Cantone ◽  
Giovanni Pennisi ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Elderly Patients ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Early Stage ◽  
Brain Magnetic Resonance Imaging ◽  
Single Pulse ◽  
Neuropsychological Profile ◽  
Resting Motor Threshold ◽  
Significant Difference

Structural corpus callosum (CC) changes in patients with leukoaraiosis (LA) are significantly associated with cognitive and motor impairment. The aim of this study is to investigate the transcallosal fibers functioning by means of transcranial magnetic stimulation (TMS) in elderly patients with LA. The resting motor threshold (rMT), the motor-evoked potentials (MEPs), and the controlateral (cSP) and ipsilateral silent periods (iSP) were determined using single-pulse TMS in 15 patients and 15 age-matched controls. The neuropsychological profile and the vascular burden at brain magnetic resonance imaging (MRI) were concomitantly explored. Patients reported abnormal scores at tests evaluating executive control functions. No significant difference was found in TMS measures of intra- and intercortical excitability. No CC lesion was evident at MRI. Transcallosal inhibitory mechanisms to TMS seem to be spared in LA patients, a finding which is in line with neuroimaging features and suggests a functional integrity of the CC despite the ischemic interruption of corticosubcortical loops implicated in cognition and behavior. The observed neurophysiological finding differs from that reported in degenerative dementia, even in the preclinical or early stage. In our group of patients, the pure extent of LA is more related to impairment of frontal lobe abilities rather than functional callosal changes.

scholarly journals Surround inhibition depends on the force exerted and is abnormal in focal hand dystonia

2009 ◽  
Vol 107 (5) ◽  
pp. 1513-1518 ◽  
Author(s):  
S. Beck ◽  
M. Schubert ◽  
S. Pirio Richardson ◽  
M. Hallett
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Neural Mechanism ◽  
Single Pulse ◽  
Movement Initiation ◽  
Focal Hand Dystonia ◽  
Surround Inhibition ◽  
Hand Dystonia

There is evidence that surround inhibition (SI), a neural mechanism to enhance contrast between signals, may play a role in primary motor cortex during movement initiation, while it is deficient in patients with focal hand dystonia (FHD). To further characterize SI with respect to different force levels, single- and paired-pulse transcranial magnetic stimulation was applied at rest and during index finger movement to evoke potentials in the nonsynergistic, abductor policis muscle. In Experiment 1, in 19 healthy volunteers, SI was tested using single-pulse transcranial magnetic stimulation. Motor-evoked potentials at rest were compared with those during contraction using four different force levels [5, 10, 20, and 40% of maximum force (Fmax)]. In Experiments 2 and 3, SI and short intracortical inhibition (SICI) were tested, respectively, in 16 patients with FHD and 20 age-matched controls for the 10% and 20% Fmax levels. SI was most pronounced for 10% Fmax and abolished for the 40% Fmax level in controls, whereas FHD patients had no SI at all. In contrast, a loss of SICI was observed in FHD patients, which was more pronounced for 10% Fmax than for 20% Fmax. Our results suggest that SI is involved in the generation of fine finger movements with low-force levels. The greater loss of SICI for the 10% Fmax level in patients with FHD than for the 20% Fmax level indicates that this inhibitory mechanism is more abnormal at lower levels of force.

scholarly journals Transcranial magnetic stimulation in cognitive neuroscience: Methodological basis and safety

2020 ◽  
Vol 7 (3) ◽  
pp. 25-44
Author(s):  
Ilya S. Bakulin ◽  
◽  
Alexandra G. Poydasheva ◽  
Alexey A. Medyntsev ◽  
Natalia A. Suponeva ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Cognitive Neuroscience ◽  
Magnetic Stimulation ◽  
Functional Brain Mapping ◽  
Non Invasive ◽  
Cognitive Studies ◽  
Virtual Lesion ◽  
Developing Method

Transcranial magnetic stimulation (TMS) is an intensively developing method of non-invasive brain stimulation. TMS is widely used in cognitive neuroscience to study the causal role of various cortical areas in visual perception, memory, attention, speech, and other cognitive functions. The article discusses the general principles and main directions of TMS applications in cognitive research as well as the modern aspects of using online TMS protocols for the creation of a temporary “virtual lesion”, functional brain mapping, and chronometric studies. Possible applications of offline TMS protocols for long-term modulation of the stimulated cortical area activity are also discussed. Methodological features of TMS studies, including targeting methods, as well as the frequency and intensity of stimulation, are highlighted. The article also describes the possibilities of combining TMS with other methods. Finally, the safety aspects of TMS in healthy subjects in the context of cognitive studies are discussed

scholarly journals A new protocol for multiple muscle mapping using nTMS

2021 ◽  
Author(s):  
Fang Jin ◽  
Sjoerd M Bruijn ◽  
Andreas Daffertshofer
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Cortical Representation ◽  
Precentral Gyrus ◽  
Validity And Reliability ◽  
Non Invasive ◽  
Centre Of Gravity

Background: Single-pulse transcranial magnetic stimulation is a safe and non-invasive tool for investigating cortical representation of muscles in the primary motor cortex. While non-navigated TMS has been successfully applied to simultaneously induce motor-evoked potentials (MEPs) in multiple muscles, a more rigorous assessment of the corresponding cortical representation can greatly benefit from navigated transcranial magnetic stimulation (nTMS). Objective: We designed a protocol to map the entire precentral gyrus using neural navigation while recording responses of eight muscles simultaneously. Here, we evaluated the feasibility, validity, and reliability of this protocol. Method: Twenty participants underwent conventional (i.e., muscle-based, grid-constrained) and gyrus-based nTMS mapping. For both protocols, we investigated three different stimulation intensities during two consecutive sessions. Results: The gyrus-based nTMS mapping was received well by all participants and was less time consuming than the grid-constrained standard. On average, MEP amplitudes, latencies, and centre-of-gravity and size of the active areas largely agreed across protocols supporting validity. Intraclass coefficients between sessions unscored the reliability of our protocol. Conclusion: We designed an nTMS protocol for the simultaneous mapping multiple muscles on the cortex. The protocol takes only about ten minutes per participant when including as many as eight muscles. Our assessments revealed that the cortical representation of multiple muscles can be determined with high validity and reliability.

scholarly journals The Role of the Right Cerebral Hemisphere in Processing Novel Metaphoric Expressions: A Transcranial Magnetic Stimulation Study

2008 ◽  
Vol 20 (1) ◽  
pp. 170-181 ◽  
Author(s):  
Gorana Pobric ◽  
Nira Mashal ◽  
Miriam Faust ◽  
Michal Lavidor
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Right Hemisphere ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Brain Activity ◽  
Inferior Frontal Gyrus ◽  
Judgment Task ◽  
Semantic Judgment ◽  
The Right

Previous research suggests that the right hemisphere (RH) may contribute uniquely to the processing of metaphoric language. However, causal relationships between local brain activity in the RH and metaphors comprehension were never established. In addition, most studies have focused on familiar metaphoric expressions which might be processed similarly to any conventional word combination. The present study was designed to overcome these two problems by employing repetitive transcranial magnetic stimulation (rTMS) to examine the role of the RH in processing novel metaphoric expressions taken from poetry. Right-handed participants were presented with four types of word pairs, literal, conventional metaphoric and novel metaphoric expressions, and unrelated word pairs, and were asked to perform a semantic judgment task. rTMS of the right posterior superior temporal sulcus disrupted processing of novel but not conventional metaphors, whereas rTMS over the left inferior frontal gyrus selectively impaired processing of literal word pairs and conventional but not novel metaphors (Experiment 1). In a further experiment, we showed that these effects were due to right-left asymmetries rather than posterior-anterior differences (Experiment 2). This is the first demonstration of TMS-induced impairment in processing novel metaphoric expressions, and as such, confirms the specialization of the RH in the activation of a broader range of related meanings than the left hemisphere, including novel, nonsalient meanings. The findings thus suggest that the RH may be critically involved in at least one important component of novel metaphor comprehension, the integration of the individual meanings of two seemingly unrelated concepts into a meaningful metaphoric expression.

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