State-dependency in brain stimulation studies of perception and cognition

Silvanto, Juha; Muggleton, Neil G.; Walsh, Vincent

doi:10.1016/j.tics.2008.09.004

Cited by 480 publications

(363 citation statements)

References 53 publications

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“…The study was based on a TMS adaptation paradigm 79 . participants were presented with 'adaptation-inducing' movies of a hand or foot acting on various objects and asked to respond as quickly as possible to a picture of a motor act similar to that of the movie.…”

Section: Inferential Reasoningmentioning

confidence: 99%

The functional role of the parieto-frontal mirror circuit: interpretations and misinterpretations

2010

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Section: Inferential Reasoningmentioning

confidence: 99%

The functional role of the parieto-frontal mirror circuit: interpretations and misinterpretations

2010

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“…Considering that the cortical response to the TMS depends on the neuronal activation state (Amassian et al, 1989;Esser et al, 2006;Huber et al, 2008;Romei et al, 2008;Silvanto et al, 2008), the cortical response strength evoked by the TMS represents a direct measure of the neuronal changes induced by the tDCS on the motor cortex.…”

Section: Tdcs-induced Changes In Cortical Excitabilitymentioning

confidence: 99%

Excitability modulation of the motor system induced by transcranial direct current stimulation: A multimodal approach

2013

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Anodal and cathodal transcranial direct current stimulations (tDCS) are both established techniques to induce cortical excitability changes. Typically, in the human motor system, such cortical modulations are inferred through changes in the amplitude of the motor evoked potentials (MEPs). However, it is now possible to directly evaluate tDCS-induced changes at the cortical level by recording the transcranial magnetic stimulation evoked potentials (TEPs) using electroencephalography (EEG). The present study investigated the modulation induced by the tDCS on the motor system. The study evaluates changes in the MEPs, in the amplitude and distribution of the TEPs, in resting state oscillatory brain activity and in behavioral performance in a simple manual response task. Both the short-and long-term tDCS effects were investigated by evaluating their time course at~0 and 30 min after tDCS. Anodal tDCS over the left primary motor cortex (M1) induced an enhancement of corticospinal excitability, whereas cathodal stimulation produced a reduction. These changes in excitability were indexed by changes in MEP amplitude. More interestingly, tDCS modulated the cortical reactivity, which is the neuronal activity evoked by TMS, in a polarity-dependent and site-specific manner. Cortical reactivity increased after anodal stimulation over the left M1, whereas it decreased with cathodal stimulation. These effects were partially present also at long term evaluation. No polarity-specific effect was found either on behavioral measures or on oscillatory brain activity. The latter showed a general increase in the power density of low frequency oscillations (theta and alpha) at both stimulation polarities. Our results suggest that tDCS is able to modulate motor cortical reactivity in a polarity-specific manner, inducing a complex pattern of direct and indirect cortical activations or inhibitions of the motor system-related network, which might be related to changes in synaptic efficacy of the motor cortex.

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“…The effect of tDCS over time was analysed by measuring performance differences across stimulation Blocks (1 and 2), as it was uncertain whether stimulation effects were stable due to so few parietal tDCS perception studies being conducted with continuous stimulation. Further, tDCS effects are state dependent and can change when the brain regions being stimulated are active (Silvanto, Muggleton, & Walsh, 2008;Walsh, 2013). Significant scores were those below the alpha level .05.…”

Section: Discussionmentioning

confidence: 99%

“…However, the effect of tDCS is not necessarily continuous. TDCS modulates cortical excitability rather than directly disrupting the neurons by causing an action potential (as with TMS), the effects of stimulation may change (Silvanto, Muggleton, & Walsh, 2008;Walsh, 2013) or be compensated for over time.…”

Section: * Discussionmentioning

confidence: 99%

Perceptual decisions regarding object manipulation are selectively impaired in apraxia or when tDCS is applied over the left IPL

et al. 2016

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This study evaluated whether apraxia can be understood as due to impaired motor representations or motor imagery necessary for appropriate object-use, imitation, and pantomime. The causal role of the left inferior parietal lobe (IPL), which is heavily implicated in apraxia, is also evaluated. These processes are appraised in light of the proposed ventro-dorsal sub-stream of the classic two visual pathway model, where perceptual information from the ventral stream and the dorsal action stream are integrated and essential for object manipulation. Using a task assessing object-use perception, stroke patients with apraxia demonstrated a selective deficit during perceptual decisions reliant on the integration of visible and known object properties to select the appropriate grasp for object-use. This deficit increased with apraxia severity. A dissociation was evident in these patients showing intact non-motoric perceptual decisions regarding the functional semantic relationship between two objects in the absence of the actor (e.g. how a hammer hits a nail). Converging evidence was found using a modified version of the same task in a neuromodulation study that directly targeted the left IPL in healthy participants using transcranial direct current stimulation (tDCS). Application of inhibitory stimulation over the left IPL reduced performance during perceptual decisions regarding object manipulation whilst performance was unaffected during functional semantic decisions. Excitatory stimulation of the left IPL did not affect performance in either task. Combined, these results suggest that the left inferior parietal lobe is critical for motor imagery, and that apraxia may be caused by an inability to use internal motor representations of object manipulation. These results are discussed in terms of motoric and non-motoric perceptual processes and the proposal of an additional ventro-dorsal sub-stream within the dorsal and ventral visual pathways model

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State-dependency in brain stimulation studies of perception and cognition

Cited by 480 publications

References 53 publications

The functional role of the parieto-frontal mirror circuit: interpretations and misinterpretations

The functional role of the parieto-frontal mirror circuit: interpretations and misinterpretations

Excitability modulation of the motor system induced by transcranial direct current stimulation: A multimodal approach

Perceptual decisions regarding object manipulation are selectively impaired in apraxia or when tDCS is applied over the left IPL

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