Studies in Cognition: The Problems Solved and Created by Transcranial Magnetic Stimulation (original) (raw)
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Neuroscience and biobehavioral reviews, 2011
Transcranial magnetic stimulation (TMS) has become a mainstay of cognitive neuroscience, thus facing new challenges due to its widespread application on behaviorally silent areas. In this review we will summarize the main technical and methodological considerations that are necessary when using TMS in cognitive neuroscience, based on a corpus of studies and technical improvements that has become available in most recent years. Although TMS has been applied only relatively recently on a large scale to the study of higher functions, a range of protocols that elucidate how this technique can be used to investigate a variety of issues is already available, such as single pulse, paired pulse, dual-site, repetitive and theta burst TMS. Finally, we will touch on recent promising approaches that provide powerful new insights about causal interactions among brain regions (i.e., TMS with other neuroimaging techniques) and will enable researchers to enhance the functional resolution of TMS (i....
Transcranial Magnetic Stimulation as a Research Tool in Cognitive Neuroscience
Transcranial magnetic stimulation (TMS) is a neurostimulation and neuromodulation technique that induces electric field in the brain based on Faraday’s principle of electro-magnetic induction and thus interferes with the neural processing. Although its roots stem to the first half of the 19th century, the first successful stimulation of the human cortex was performed in 1985 by Barker (Barker, Jalinous, & Freeston, 1985). Since then, the number of published papers reporting the use of TMS has been increasing rapidly (Rossi, Hallett, Rossini, & Pascual-Leone, 2009). Despite the growing popularity of the method, the mechanisms by which it influences brain activity are not completely understood. This review gives a brief overview of the recent theories and the supporting evidence. However, the main focus of this review is the use of TMS as a research tool in cognitive neuroscience and neuropsychology. I will try to illustrate the broad possibilities of application of TMS in these fields, what questions it could answer, how this technique could be combined with neuroimaging, and discuss the safety considerations related to the use of TMS in non-clinical settings.
Transcranial Magnetic Stimulation Intensities in Cognitive Paradigms
PLoS ONE, 2011
Background: Transcranial magnetic stimulation (TMS) has become an important experimental tool for exploring the brain's functional anatomy. As TMS interferes with neural activity, the hypothetical function of the stimulated area can thus be tested. One unresolved methodological issue in TMS experiments is the question of how to adequately calibrate stimulation intensities. The motor threshold (MT) is often taken as a reference for individually adapted stimulation intensities in TMS experiments, even if they do not involve the motor system. The aim of the present study was to evaluate whether it is reasonable to adjust stimulation intensities in each subject to the individual MT if prefrontal regions are stimulated prior to the performance of a cognitive paradigm. Methods and Findings: Repetitive TMS (rTMS) was applied prior to a working memory task, either at the 'fixed' intensity of 40% maximum stimulator output (MSO), or individually adapted at 90% of the subject's MT. Stimulation was applied to a target region in the left posterior middle frontal gyrus (pMFG), as indicated by a functional magnetic resonance imaging (fMRI) localizer acquired beforehand, or to a control site (vertex). Results show that MT predicted the effect size after stimulating subjects with the fixed intensity (i.e., subjects with a low MT showed a greater behavioral effect). Nevertheless, the individual adaptation of intensities did not lead to stable effects. Conclusion: Therefore, we suggest assessing MT and account for it as a measure for general cortical TMS susceptibility, even if TMS is applied outside the motor domain.
Current Opinion in Neurobiology, 2000
Fifteen years after its introduction by Anthony Barker, transcranial magnetic stimulation (TMS) appears to be 'coming of age' in cognitive neuroscience and promises to reshape the way we investigate brain-behavior relations. Among the many methods now available for imaging the activity of the human brain, magnetic stimulation is the only technique that allows us to interfere actively with brain function. As illustrated by several experiments over the past couple of years, this property of TMS allows us to investigate the relationship between focal cortical activity and behavior, to trace the timing at which activity in a particular cortical region contributes to a given task, and to map the functional connectivity between brain regions.
Meeting Report: Transcranial Magnetic Stimulation and Studies of Human Cognition
Journal of Cognitive Neuroscience, 2000
Cognitive neuroscience studies how the physical structure of the brain subserves the cognitive processes of the mind. Such studies with humans are hampered by technical difficulties. One classic approach to human subject studies has been observing the cognitive performance of individuals who have suffered focal brain injuries. More recently, non-invasive brain monitoring has allowed investigation of how human cognitive performance is linked with neural substrates in intact human subjects. A number of such non-invasive brain monitoring tools have been developed, each with its own individual strengths and weaknesses. EEG and MEG detect neural activity during cognitive performance with good temporal resolution but are less useful for identifying precisely where in the brain the neural activity is occurring. PET and fMRI, monitoring signals correlated with hemodynamic and metabolic indicators of neuronal activity, provide good spatial identification of brain areas involved in the performance of cognitive tasks, but are limited
Transcranial magnetic stimulation studies of cognition: an emerging field
Experimental Brain Research, 2000
The authors have worked to ensure that all information in this book is accurate at the time of publication and consistent with general psychiatric and medical standards, and that information concerning drug dosages, schedules, and routes of administration is accurate at the time of publication and consistent with standards set by the U.S. Food and Drug Administration and the general medical community. As medical research and practice continue to advance, however, therapeutic standards may change. Moreover, specific situations may require a specific therapeutic response not included in this book. For these reasons and because human and mechanical errors sometimes occur, we recommend that readers follow the advice of physicians directly involved in their care or the care of a member of their family.
Brain Research Reviews, 2003
Transcranial magnetic stimulation (TMS) is a widely used tool for the non-invasive study of basic neurophysiological processes and the relationship between brain and behavior. We review the physical and physiological background of TMS and discuss the large body of perceptual and cognitive studies, mainly in the visual domain, that have been performed with TMS in the past 15 years. We compare TMS with other neurophysiological and neuropsychological research tools and propose that TMS, compared with the classical neuropsychological lesion studies, can make its own unique contribution. As the main focus of this review, we describe the different approaches of combining TMS with functional neuroimaging techniques. We also discuss important shortcomings of TMS, especially the limited knowledge concerning its physiological effects, which often make the interpretation of TMS results ambiguous. We conclude with a critical analysis of the resulting conceptual and methodological limitations that the investigation of functional brain-behavior relationships still has to face. We argue that while some of the methodological limitations of TMS applied alone can be overcome by combination with functional neuroimaging, others will persist until its physical and physiological effects can be controlled.
Cortex, 2009
Transcranial magnetic stimulation (TMS) uses a magnetic field to "carry" a short lasting electrical current pulse into the brain where it stimulates neurones, particularly in superficial regions of cerebral cortex. TMS can interfere with cognitive functions in two ways. A high intensity TMS pulse causes a synchronised high frequency burst of discharge in a relatively large population of neurones that is terminated by a long lasting GABAergic inhibition. The combination of artificial synchronisation of activity followed by depression effectively disrupts perceptual, motor and cognitive processes in the human brain. This transient neurodisruption has been termed a "virtual lesion". Smaller intensities of stimulation produce less activity; in such cases, cognitive operations can probably continue but are disrupted because of the added noisy input from the TNS pulse. It is usually argued that if a TMS pulse affects performance, then the area stimulated must provide an essential contribution to behaviour being studied. However, there is one exception to this: the pulse could be applied to an area that is not involved in the task but which has projections to the critical site. Activation of outputs from the site of stimulation could potentially disrupt processing at the distant site, interfering with behaviour without having any involvement in the task. A final important feature of the response to TMS is "context dependency", which indicates that the response depends on how excitable the cortex is at the time the stimulus is applied: if many neurones are close to firing threshold then the more of them are recruited by the pulse than at rest. Many studies have noted this context-dependent modulation. However, it is often assumed that the excitability of an area has a simple relationship to activity in that area. We argue that this is not necessarily the case. Awareness of the problem may help resolve some apparent anomalies in the literature.
Transcranial Magnetic and Electric Stimulation in Perception and Cognition Research
Frontiers in Neuroscience, 2012
In recent years, we have witnessed the emergence of new techniques for studying the mechanisms that underlie perceptual and cognitive function in the human brain. An important contribution has come from the introduction of non-invasive brain stimulation (NIBS). The development of NIBS techniques to study perception and cognition constitutes a significant breakthrough in our understanding of the changes in the brain that may account for behavioral plasticity. NIBS approaches aim to induce changes in the activity of the brain, which can lead to alterations in the performance of a wide range of behavioral tasks (Sandrini et al. 2011). NIBS techniques that are used to modulate cortical activity include transcranial magnetic stimulation (TMS) contents