The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Walsh Vincent - One of the best experts on this subject based on the ideXlab platform.
-
Transcranial Magnetic Stimulation and the Understanding of Behavior
'Annual Reviews', 2021Co-Authors: Pitcher David, Parkin B., Walsh VincentAbstract:The development of the use of transcranial magnetic stimulation (TMS) in the study of psychological functions has entered a new phase of sophistication. This is largely due to an increasing physiological knowledge of its effects and to its being used in combination with other experimental techniques. This review presents the current state of our understanding of the mechanisms of TMS in the context of designing and interpreting psychological experiments. We discuss the major conceptual advances in behavioral studies using TMS. There are meaningful physiological and technical achievements to review, as well as a wealth of new perceptual and cognitive experiments. In doing so we summarize the different uses and challenges of TMS in mental Chronometry, perception, awareness, learning, and memory. Expected final online publication date for the , Volume 72 is January 5, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates
Alexander T Sack - One of the best experts on this subject based on the ideXlab platform.
-
the Chronometry of visual perception review of occipital tms masking studies
Neuroscience & Biobehavioral Reviews, 2014Co-Authors: Tom A De Graaf, Christianne Jacobs, Mika Koivisto, Alexander T SackAbstract:Transcranial magnetic stimulation (TMS) continues to deliver on its promise as a research tool. In this review article we focus on the application of TMS to early visual cortex (V1, V2, V3) in studies of visual perception and visual awareness. Depending on the asynchrony between visual stimulus onset and TMS pulse (SOA), TMS can suppress visual perception, allowing one to track the time course of functional relevance (Chronometry) of early visual cortex for vision. This procedure has revealed multiple masking effects (‘dips’), some consistently (∼+100 ms SOA) but others less so (∼−50 ms, ∼−20 ms, ∼+30 ms, ∼+200 ms SOA). We review the state of TMS masking research, focusing on the evidence for these multiple dips, the relevance of several experimental parameters to the obtained ‘masking curve’, and the use of multiple measures of visual processing (subjective measures of awareness, objective discrimination tasks, priming effects). Lastly, we consider possible future directions for this field. We conclude that while TMS masking has yielded many fundamental insights into the Chronometry of visual perception already, much remains unknown. Not only are there several temporal windows when TMS pulses can induce visual suppression, even the well-established ‘classical’ masking effect (∼+100 ms) may reflect more than one functional visual process.
-
fmri effective connectivity and tms Chronometry complementary accounts of causality in the visuospatial judgment network
PLOS ONE, 2009Co-Authors: Tom A De Graaf, Christianne Jacobs, Alard Roebroeck, Alexander T SackAbstract:Background While traditionally quite distinct, functional neuroimaging (e.g. functional magnetic resonance imaging: fMRI) and functional interference techniques (e.g. transcranial magnetic stimulation: TMS) increasingly address similar questions of functional brain organization, including connectivity, interactions, and causality in the brain. Time-resolved TMS over multiple brain network nodes can elucidate the relative timings of functional relevance for behavior (“TMS Chronometry”), while fMRI functional or effective connectivity (fMRI EC) can map task-specific interactions between brain regions based on the interrelation of measured signals. The current study empirically assessed the relation between these different methods. Methodology/Principal Findings One group of 15 participants took part in two experiments: one fMRI EC study, and one TMS Chronometry study, both of which used an established cognitive paradigm involving one visuospatial judgment task and one color judgment control task. Granger causality mapping (GCM), a data-driven variant of fMRI EC analysis, revealed a frontal-to-parietal flow of information, from inferior/middle frontal gyrus (MFG) to posterior parietal cortex (PPC). FMRI EC-guided Neuronavigated TMS had behavioral effects when applied to both PPC and to MFG, but the temporal pattern of these effects was similar for both stimulation sites. At first glance, this would seem in contradiction to the fMRI EC results. However, we discuss how TMS Chronometry and fMRI EC are conceptually different and show how they can be complementary and mutually constraining, rather than contradictory, on the basis of our data. Conclusions/Significance The findings that fMRI EC could successfully localize functionally relevant TMS target regions on the single subject level, and conversely, that TMS confirmed an fMRI EC identified functional network to be behaviorally relevant, have important methodological and theoretical implications. Our results, in combination with data from earlier studies by our group (Sack et al., 2007, Cerebral Cortex), lead to informed speculations on complex brain mechanisms, and TMS disruption thereof, underlying visuospatial judgment. This first in-depth empirical and conceptual comparison of fMRI EC and TMS Chronometry thereby shows the complementary insights offered by the two methods.
Pitcher David - One of the best experts on this subject based on the ideXlab platform.
-
Transcranial Magnetic Stimulation and the Understanding of Behavior
'Annual Reviews', 2021Co-Authors: Pitcher David, Parkin B., Walsh VincentAbstract:The development of the use of transcranial magnetic stimulation (TMS) in the study of psychological functions has entered a new phase of sophistication. This is largely due to an increasing physiological knowledge of its effects and to its being used in combination with other experimental techniques. This review presents the current state of our understanding of the mechanisms of TMS in the context of designing and interpreting psychological experiments. We discuss the major conceptual advances in behavioral studies using TMS. There are meaningful physiological and technical achievements to review, as well as a wealth of new perceptual and cognitive experiments. In doing so we summarize the different uses and challenges of TMS in mental Chronometry, perception, awareness, learning, and memory. Expected final online publication date for the , Volume 72 is January 5, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates
Tom A De Graaf - One of the best experts on this subject based on the ideXlab platform.
-
the Chronometry of visual perception review of occipital tms masking studies
Neuroscience & Biobehavioral Reviews, 2014Co-Authors: Tom A De Graaf, Christianne Jacobs, Mika Koivisto, Alexander T SackAbstract:Transcranial magnetic stimulation (TMS) continues to deliver on its promise as a research tool. In this review article we focus on the application of TMS to early visual cortex (V1, V2, V3) in studies of visual perception and visual awareness. Depending on the asynchrony between visual stimulus onset and TMS pulse (SOA), TMS can suppress visual perception, allowing one to track the time course of functional relevance (Chronometry) of early visual cortex for vision. This procedure has revealed multiple masking effects (‘dips’), some consistently (∼+100 ms SOA) but others less so (∼−50 ms, ∼−20 ms, ∼+30 ms, ∼+200 ms SOA). We review the state of TMS masking research, focusing on the evidence for these multiple dips, the relevance of several experimental parameters to the obtained ‘masking curve’, and the use of multiple measures of visual processing (subjective measures of awareness, objective discrimination tasks, priming effects). Lastly, we consider possible future directions for this field. We conclude that while TMS masking has yielded many fundamental insights into the Chronometry of visual perception already, much remains unknown. Not only are there several temporal windows when TMS pulses can induce visual suppression, even the well-established ‘classical’ masking effect (∼+100 ms) may reflect more than one functional visual process.
-
fmri effective connectivity and tms Chronometry complementary accounts of causality in the visuospatial judgment network
PLOS ONE, 2009Co-Authors: Tom A De Graaf, Christianne Jacobs, Alard Roebroeck, Alexander T SackAbstract:Background While traditionally quite distinct, functional neuroimaging (e.g. functional magnetic resonance imaging: fMRI) and functional interference techniques (e.g. transcranial magnetic stimulation: TMS) increasingly address similar questions of functional brain organization, including connectivity, interactions, and causality in the brain. Time-resolved TMS over multiple brain network nodes can elucidate the relative timings of functional relevance for behavior (“TMS Chronometry”), while fMRI functional or effective connectivity (fMRI EC) can map task-specific interactions between brain regions based on the interrelation of measured signals. The current study empirically assessed the relation between these different methods. Methodology/Principal Findings One group of 15 participants took part in two experiments: one fMRI EC study, and one TMS Chronometry study, both of which used an established cognitive paradigm involving one visuospatial judgment task and one color judgment control task. Granger causality mapping (GCM), a data-driven variant of fMRI EC analysis, revealed a frontal-to-parietal flow of information, from inferior/middle frontal gyrus (MFG) to posterior parietal cortex (PPC). FMRI EC-guided Neuronavigated TMS had behavioral effects when applied to both PPC and to MFG, but the temporal pattern of these effects was similar for both stimulation sites. At first glance, this would seem in contradiction to the fMRI EC results. However, we discuss how TMS Chronometry and fMRI EC are conceptually different and show how they can be complementary and mutually constraining, rather than contradictory, on the basis of our data. Conclusions/Significance The findings that fMRI EC could successfully localize functionally relevant TMS target regions on the single subject level, and conversely, that TMS confirmed an fMRI EC identified functional network to be behaviorally relevant, have important methodological and theoretical implications. Our results, in combination with data from earlier studies by our group (Sack et al., 2007, Cerebral Cortex), lead to informed speculations on complex brain mechanisms, and TMS disruption thereof, underlying visuospatial judgment. This first in-depth empirical and conceptual comparison of fMRI EC and TMS Chronometry thereby shows the complementary insights offered by the two methods.
Alvaro Pascualleone - One of the best experts on this subject based on the ideXlab platform.
-
hearing shapes our perception of time temporal discrimination of tactile stimuli in deaf people
Journal of Cognitive Neuroscience, 2012Co-Authors: Nadia Bolognini, Carlo Cecchetto, Carlo Geraci, Angelo Maravita, Alvaro Pascualleone, Costanza PapagnoAbstract:Confronted with the loss of one type of sensory input, we compensate using information conveyed by other senses. However, losing one type of sensory information at specific developmental times may lead to deficits across all sensory modalities. We addressed the effect of auditory deprivation on the development of tactile abilities, taking into account changes occurring at the behavioral and cortical level. Congenitally deaf and hearing individuals performed two tactile tasks, the first requiring the discrimination of the temporal duration of touches and the second requiring the discrimination of their spatial length. Compared with hearing individuals, deaf individuals were impaired only in tactile temporal processing. To explore the neural substrate of this difference, we ran a TMS experiment. In deaf individuals, the auditory association cortex was involved in temporal and spatial tactile processing, with the same Chronometry as the primary somatosensory cortex. In hearing participants, the involvement of auditory association cortex occurred at a later stage and selectively for temporal discrimination. The different Chronometry in the recruitment of the auditory cortex in deaf individuals correlated with the tactile temporal impairment. Thus, early hearing experience seems to be crucial to develop an efficient temporal processing across modalities, suggesting that plasticity does not necessarily result in behavioral compensation.
-
transcranial magnetic stimulation in cognitive neuroscience virtual lesion Chronometry and functional connectivity
Current Opinion in Neurobiology, 2000Co-Authors: Alvaro Pascualleone, Vincent Walsh, J C RothwellAbstract: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.
