Mechanisms of Sustained Increases of Firing Rate of Neurones in the Rat Cerebral Cortex after Polarization: Role of Protein Synthesis

Gartside, I B

doi:10.1038/220383a0

Cited by 118 publications

(79 citation statements)

References 6 publications

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“…The after-effects of tDCS are known to be dependent on this ongoing protein synthesis that occurs during the stimulation period, as well as on increased functioning of NMDA receptors which facilitate synaptic transmission. Administration of both protein inhibitors in animal models and NMDA receptor antagonists in humans is able to nullify these after-effects (Gartside 1968;Nitsche et al 2003). This suggests that online tDCS interacts with the brain's normal plastic response, which allows for the continued manifestation of effects offline.…”

Section: Neurobiology Of Consolidation and Tdcsmentioning

confidence: 94%

“…Furthermore, stimulation during sleep seems especially fruitful for declarative memory enhancement if timed during the appropriate consolidation period during slow-wave sleep (Barham et al 2016). Therefore, it is possible that while online stimulation may promote LTP-related protein synthesis at the synapse (Gartside 1968), offline stimulation after task completion or during sleep may directly enhance learning-associated neural replay and system consolidation for long-term retention. Future research should systematically evaluate the mechanisms and relative efficacy of online and offline (after task) stimulation.…”

Section: Timing Of Stimulationmentioning

confidence: 99%

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Optimizing Transcranial Direct Current Stimulation Protocols to Promote Long-Term Learning

Karsten

Buschkuehl

et al. 2017

J Cogn Enhanc

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Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that has the potential to induce polarity-specific changes in neural activity within targeted brain regions. There is growing interest in the use of this technology for the enhancement of higher cognitive functions, and application of tDCS directly before or concomitant with task performance has shown promise in modulating a range of behavioral outcomes, including motor skill acquisition, working memory performance, and implicit and explicit learning. The proposed mechanism for the observed enhancements is a temporary and targeted shift in the excitability of the cortical regions that subserve the relevant tasks, lasting from minutes up to about an hour after cessation of stimulation. Although empirical work does support at least a partial role for this mechanism, an arguably more potent but relatively underexplored phenomenon is thought to occur in the hours or days after stimulation-that is, a facilitation of consolidative processes. Here, we review the literature describing the nature of tDCS-enhanced consolidation and argue that some of the mixed results among the single-session studies that currently dominate the extant literature may be explained by a failure to take advantage of these potentially powerful offline effects. Accordingly, we further contend that the full potential of tDCS cannot be truly realized without a longitudinal design which allows for tDCS to act directly upon learning by promoting consolidation between sessions. Finally, we review preliminary evidence that these consolidation effects can be even further enhanced via strategically spaced out stimulation sessions, which take advantage of a long-held tenet in the literature that distributed learning produces better outcomes than massed learning. We conclude by proposing potential study designs to encourage the use of tDCS as more than merely a method to promote temporary enhancement, but also a technique to enhance long-term learning.

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Section: Neurobiology Of Consolidation and Tdcsmentioning

confidence: 94%

Section: Timing Of Stimulationmentioning

confidence: 99%

Optimizing Transcranial Direct Current Stimulation Protocols to Promote Long-Term Learning

Karsten

Buschkuehl

et al. 2017

J Cogn Enhanc

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“…When given for a period longer than ϳ5 min, DCs applied directly to the surface of the rat cortex cause both immediate and long-lasting changes in the level of activity of pyramidal neurons: discharge is increased by anodal polarization or decreased by cathodal polarization (Bindman et al, 1962(Bindman et al, , 1964Purpura and McMurry, 1965;Gartside, 1968). Our model is as follows: in the human motor cortex, a TDCSinduced change in postsynaptic activity of cortical neurons causes an activity-dependent adjustment of the long-term modification threshold for (synaptic) plasticity induced by rTMS.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast to phasic suprathreshold stimulation of cortical neurons evoked by rTMS, TDCS causes a tonic subthreshold facilitation or inhibition of cortical neurons depending on the polarity of the current. On the basis of animal studies published in the 1960s (Bindman et al, 1962(Bindman et al, , 1964Gartside, 1968), it has been proposed that the primary mechanism of action of TDCS is a polarity-specific shift of resting membrane potentials in cortical neurons resulting in secondary alterations of spontaneous discharge rates.…”

Section: Methodsmentioning

confidence: 99%

Preconditioning of Low-Frequency Repetitive Transcranial Magnetic Stimulation with Transcranial Direct Current Stimulation: Evidence for Homeostatic Plasticity in the Human Motor Cortex

Siebner¹,

Lang²,

Rizzo³

et al. 2004

J. Neurosci.

622

406

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Recent experimental work in animals has emphasized the importance of homeostatic plasticity as a means of stabilizing the properties of neuronal circuits. Here, we report a phenomenon that indicates a homeostatic pattern of cortical plasticity in healthy human subjects. The experiments combined two techniques that can produce long-term effects on the excitability of corticospinal output neurons: transcranial direct current stimulation (TDCS) and repetitive transcranial magnetic stimulation (rTMS) of the left primary motor cortex. "Facilitatory preconditioning" with anodal TDCS caused a subsequent period of 1 Hz rTMS to reduce corticospinal excitability to below baseline levels for Ͼ20 min. Conversely, "inhibitory preconditioning" with cathodal TDCS resulted in 1 Hz rTMS increasing corticospinal excitability for at least 20 min. No changes in excitability occurred when 1 Hz rTMS was preceded by sham TDCS. Thus, changing the initial state of the motor cortex by a period of DC polarization reversed the conditioning effects of 1 Hz rTMS. These preconditioning effects of TDCS suggest the existence of a homeostatic mechanism in the human motor cortex that stabilizes corticospinal excitability within a physiologically useful range.

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“…In fact, blocking voltage-dependent channels for Na+ and Ca2+ inhibited the short and long-term effects of anodal stimulation, without affecting the effects of cathodic stimulation. This suggests that a component of the effects of neuronal hyperexcitability induced by anodal stimulation is dependent on intrinsic membrane properties related to voltage-sensitive channels for Na+ and Ca2+ 34,[43][44][45] . In addition, these effects are potentiated by factors related to excitatory neurotransmission.…”

Section: Neurophysiological Backgroundmentioning

confidence: 99%

Neurophysiological basis of a new electrode configuration to potentiate the tDCS: Protocols for upper limbs

Cavalcanti

Gomes²,

Baptista³

et al. 2017

Rev Pesq Fisio

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| Transcranial Direct Current Stimulation (tDCS)uses a direct electrical current to modulate the activity of cortical neurons. Anodal tDCS (positive pole) increases the excitability of cortical neurons, while cathodic tDCS (negative pole) reduces it. However, when applied in the peripheral nervous system the effects are the opposite of cranial application. Furthermore, when central and peripheral stimuli are used concomitantly, their effects can be summed up. This has been demonstrated by combining tDCS with other forms of sensory peripheral stimulation. We propose a new electrode configuration to potentiate the excitatory and inhibitory effects of tDCS on neuronal excitability and increase upper limb motor function. Our hypothesis is that placement of the electrodes in the primary motor cortex (M1) and the contralateral brachial plexus (BP) would promote this potentiation by central and peripheral synaptic summation. We will test our hypothesis in two proof-of-concept studies. Study 1) Secondary trial, in which we will evaluate the effects of these configurations on the neuronal excitability of healthy individuals; Study 2) A double-blind, randomized and crossover clinical trial in which we will test the stimulation with the anode in M1 and the cathode in the contralateral BP on the motor function and electrophysiological markers of individuals with cerebral palsy. The effects of the new configurations will be compared with the conventional configuration (M1/ contralateral supraorbital region). We expect that our investigations will identify a more efficient way to apply tDCS and consequently a better clinical use of this technique.

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Mechanisms of Sustained Increases of Firing Rate of Neurones in the Rat Cerebral Cortex after Polarization: Role of Protein Synthesis

Cited by 118 publications

References 6 publications

Optimizing Transcranial Direct Current Stimulation Protocols to Promote Long-Term Learning

Optimizing Transcranial Direct Current Stimulation Protocols to Promote Long-Term Learning

Preconditioning of Low-Frequency Repetitive Transcranial Magnetic Stimulation with Transcranial Direct Current Stimulation: Evidence for Homeostatic Plasticity in the Human Motor Cortex

Neurophysiological basis of a new electrode configuration to potentiate the tDCS: Protocols for upper limbs

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