1,721,490 research outputs found
Transcranial brain stimulation: potential and limitations
No full textThe brain adapts to new requirements in response to activity, learning or reactions to environmental stimuli by continuous reorganization. These reorganization processes can be facilitated and augmented, or also inhibited and prevented, by transcranial neurostimulation. The most common methods are electrical or magnetic stimulation. Few studies have dealt with the newer methods using near infrared or ultrasound stimulation. Transcranial magnet stimulation (TMS) allows the pain-free transfer of very short bursts of high intensity electrical energy through the skull and can induce action potentials. By varying the number and intensity of the stimuli, and the stimulus sequence, repetitive TMS (rTMS) can induce either inhibitory or facilitatory effects in the brain. A differentiation is made between short-lived interference with ongoing brain activity, and plastic changes that persist for a longer period beyond the end of the stimulation. Weaker electric fields in the I mA range can be applied painlessly through the skull. These probably exert their effects by modulating neuronal membranes and influencing the spontaneous firing rate of cortical neurons. They encompass the range from transcranial direct current stimulation (tDCS) to high frequency alternating current stimulation (tACS) in the kilohertz range. In view of the multitude of physically possible stimulation algorithms, hypothesis-driven protocols based on cellular or neuronal network characteristics are particularly popular, in the effort to narrow the choices in a meaningful manner. Examples are theta burst stimulation or tACS in the so-called "ripple" frequency range. It is, of course, not possible to selectively stimulate individual neurons using transcranial stimulation techniques, however selective after-effects can be achieved when used in combination with neuropharmacologically active drugs. The use of these methods for neuroenhancement is now a topic of intense discussion
On the difficulties of separating retinal from cortical origins of phosphenes when using transcranial alternating current stimulation (tACS)
No full textTranscranial Stimulation Procedures 2011
No full textRecent research has contributed to a deeper understanding of transcranial electrical and magnetic stimulation procedures. In the case of transcranial magnetic stimulation (TMS) the theta burst technique is frequently used in the basic research field. In this way it is possible to achieve stronger after effects with less stimulations in comparison to repetitive transcranial stimulation procedures with an unmodulated stimulation sequence pattern. The quadro pulse technique can be considered as a further special procedure but because of its high technical requirements it is only used in the laboratory as yet. The Val-Met polymoprphism of the BDNF gene seems to play a major role in the efficacy of theta-burst stimulation. It is not pissible to achieve an arbitrary lengthening of the after effects simply by lengthening the duration of stimulation, this can in fact even have the opposite effect. This also holds for transcranial direct current stimulation (tDCS). Related new procedures include transcranial noise current stimulation (tRNS) and transcranial alternating current stimulation (tACS). In the region between about 5 and 50 Hz phosphenes, predominantly retinal are generated while in the region from 100 to 250 Hz probably high frequency neuronal oscillations in the so-called ripple frequency region and, more recently, by stimulation in the KHz region - via an interference with neuronal membrane plasticity - are created
Transcranial brain stimulation: potential and limitations
No full textThe brain adapts to new requirements in response to activity, learning or reactions to environmental stimuli by continuous reorganization. These reorganization processes can be facilitated and augmented, or also inhibited and prevented, by transcranial neurostimulation. The most common methods are electrical or magnetic stimulation. Few studies have dealt with the newer methods using near infrared or ultrasound stimulation. Transcranial magnet stimulation (TMS) allows the pain-free transfer of very short bursts of high intensity electrical energy through the skull and can induce action potentials. By varying the number and intensity of the stimuli, and the stimulus sequence, repetitive TMS (rTMS) can induce either inhibitory or facilitatory effects in the brain. A differentiation is made between short-lived interference with ongoing brain activity, and plastic changes that persist for a longer period beyond the end of the stimulation. Weaker electric fields in the I mA range can be applied painlessly through the skull. These probably exert their effects by modulating neuronal membranes and influencing the spontaneous firing rate of cortical neurons. They encompass the range from transcranial direct current stimulation (tDCS) to high frequency alternating current stimulation (tACS) in the kilohertz range. In view of the multitude of physically possible stimulation algorithms, hypothesis-driven protocols based on cellular or neuronal network characteristics are particularly popular, in the effort to narrow the choices in a meaningful manner. Examples are theta burst stimulation or tACS in the so-called "ripple" frequency range. It is, of course, not possible to selectively stimulate individual neurons using transcranial stimulation techniques, however selective after-effects can be achieved when used in combination with neuropharmacologically active drugs. The use of these methods for neuroenhancement is now a topic of intense discussion
Toward Establishing a Therapeutic Window for rTMS by Theta Burst Stimulation
No full textAbstractIn this issue of Neuron, Huang et al. show that a version of the classic theta burst stimulation protocol used to induce LTP/LTD in brain slices can be adapted to a transcranial magnetic stimulation (TMS) protocol to rapidly produce long lasting (up to an hour), reversible effects on motor cortex physiology and behavior. These results may have important implications for the development of clinical applications of rTMS in the treatment of depression, epilepsy, Parkinson's, and other diseases
Transcranial static magnetic field stimulation in man: making things as simple as possible?
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