Artifacts in TMS and TES Technique Flashcards
What is the potential issue associated with auditory click during TMS?
Auditory click can be noisy, annoying, and distracting, with rhythmic patterns; a solution is to use earplugs, white noise, or similar noise in control conditions.
How can mechanical vibrations on the skull during TMS affect data collection, and what is the suggested solution?
Mechanical vibrations allow participants to discriminate intensity and guess the locus of stimulation; shock absorbers and sham stimulation with similar vibration can be used as a solution.
What are the potential side effects of TMS involving cranial nerves or muscles, and how can they be addressed?
Pain and twitches can be distracting side effects; solutions include coil orientation change, offline stimulation, and selecting less susceptible subjects.
How can noise in TMS affect data interpretation, and what are suggested control conditions?
TMS-induced noise might produce non-specific effects; control conditions include using another cortical site, a baseline task condition, and sham or lower intensity stimulation.
How can sensory side effects during TMS be mitigated, and what is the recommended control for sham TMS?
Sham TMS involves positioning the coil to lose power or using a placebo coil; it offers better control than no-TMS condition, but control task/site is recommended.
What is the primary concern regarding heat during TMS, and what are the suggested solutions?
The coil warming up is a concern; solutions include changing coils, self-refrigerating coils, or modifying the experimental design if possible.
What are the different methods for locating the target site during TMS, and what is the trade-off between them?
Methods include external anatomical landmarks, functional methods, and neuro-navigation; the trade-off is between accuracy and feasibility/speed/cost.
How is the control site selected in TMS, and why is the selection of the homologous region often preferred?
Control site selection considers areas without direct connections, not involved in the task, and not too distant; homologous regions are preferred for lateralized functions.
What is the problem associated with the coil warming up during TMS sessions, and what are the possible solutions?
The coil warming up can affect the magnetic field; solutions include changing coils, self-refrigerating coils, or modifying the experimental design.
What are the potential side effects of TMS, and what is the most dangerous one reported in certain cases?
Possible side effects include seizures (most dangerous, reported in patients), hearing loss, heating of the brain, scalp burns, and effects on cognition and mood.
How can seizures be induced during TMS, and what preventive measures are suggested?
Seizures are caused by the spread of excitation; prevention involves monitoring with visual/EMG/EEG and a pre-TMS checklist.
What is the risk associated with hearing during TMS, and how can it be reduced?
TMS produces loud clicks; the risk is reduced with earplugs.
What is the potential effect of TMS on mood in healthy subjects, and how does it depend on the site of stimulation?
TMS can lead to subtle changes in mood; inhibitory rTMS on the left frontal cortex may worsen mood, while inhibitory rTMS on the right frontal cortex may improve mood.
What are the contraindications for TMS, and why is informed consent necessary?
Contraindications include metallic hardware, history of seizures, certain medications, pregnancy, serious head trauma, stroke, brain surgery, and other medical/neurologic conditions; informed consent is necessary to disclose all significant risks.
What are the levels of risk in TMS, and what determines the class of risk?
Class I has a direct clinical benefit with moderate risk, Class II has potential but unproven benefit with low risk, and Class III has no expected benefit with stringent safety guidelines.
What is the basic principle behind transcranial electric stimulation (TES), and what are the different types of TES?
TES involves the flow of electrical current on the scalp; types include transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), transcranial random noise stimulation (tRNS), and transcranial pulsed current stimulation (tPCS).
What is the most common TES technique, and what does tDCS modulate without inducing action potentials?
Transcranial direct current stimulation (tDCS) is the most common; it modulates excitability of neurons without inducing action potentials.
How does anodal tDCS affect neural excitability, and what are the factors influencing tDCS effects?
Anodal tDCS increases neural excitability; factors include intensity, protocol type, task, neural excitability, intra- and inter-individual variability, and electrode montage.
What are the tools required for tDCS, and how can electrode montage be done according to the 10/20 EEG system?
Tools include a stimulator, electrodes/pads, and electro-conductive gel; electrode montage is based on the 10/20 EEG system, with anode on a proxy position on the scalp.
What is the purpose of sham tDCS, and what safety issues should be considered?
Sham tDCS is an ineffective form used as a control condition; safety issues include age restrictions, metal in the head, history of seizures, medications, medical conditions, headaches, neck aches, hearing changes, syncope, and pregnancy.
