Neurostimulation Flashcards
What makes Brain Stimulation Special as a method?
it provides causal information i.e. what areas are necessary and sufficient to realize certain mental states / behaviours
What kind of information can be gained from virtual lesion studies?
What areas are Necessary for a certian behaviour/ mental state. (f.e. inhibiting region x leading to failure to execute function y)
What kind of information can be gained from Brain Stimulation?
What brain areas are Sufficient for a certian behaviour/ mental state. (f.e. stimulation of area x leads to raising of left middle finger)
What are the main things to think/worry about when interpreting the results of Brain Stimulation?
- Spatial Specificity: neighbouring regions might be stimulated. It might be these instead of the region of interest that is causing the observed phenomena.
- temporal specificity: matters for causal chain and determining what time a certian process requires.
- Intesity, Duration and inter-stimulation duration: accumualtion can happen, causing neighbouring regions to also be stimualted and fot the effect to last a longer time. (also: different levels of activiation lead to different outcomes)
Why does the protocol not tell us whether the effect of brain stimualtion is inhibitory or excitatory?
What matters is protocol (excitatory or inhibitory) IN COMBINATION with the type of brain region (excitatory or inhibitory) -> determine the outcome jointly
What are the challenges and the best option for a sham condition in brain stimulation experiments?
challenges: needs to be similar enough regarding somatosensory, sound and coil position.
best solution: sham condition = subthresholdt stimulation
Why can a bad temporal resolution be a good thing in Brain Stimulation?
In Clinical Applications a “poor” temproal resolution simply means a prolonged effect.
What are the two main types of brain stimulation methods?
invasive and non-invasive
What are the two subtypes of invasice Brain Stimulation?
- Deep Brain Stimulation (inhibitory)
- Electrical Brain Stimulation
Give an example of why intensitiy matters for brain stimulation research.
Different intensities can lead to different outcomes. F.e. Reported sensing of intention after weak stiualtion to parietal regions. Illusionary movement with stronger stimulation in parietal region.
What are the drawbacks of invasive brain stimulation in research?
- can only be used on people which need medical attention (brains open).
- Paradigm Choice limitation: Cannot perform every taks when your skull is open.
- As the sample is limited to people with neurological problems there is a problem with generalizing to a greater population as neurplasticity and compensation might have changed functional networks in the test subjects.
What are the two different methods used for non-invasive brain stimulation?
Transcranial electric stimulation (TES) and Transcranial Magnetic Stimulation (TMS)
Explain the basic working principle of TMS and how inhibition and excitation can be achieved.
Magnetic fields serve as a vehicle for electrical current. Trigger (high frequency) or suppress (low frequency) action potentials in target regions.
What are the protocols of TMS?
single (immediate effect)
paired-pulse and
repetitive TMS (pro-longed effect)
Explain the basic working principle of TES
Electrical Current is passed through the skull using 2 electrodes.
Unlike TMS TES is not strong enough to trigger action potentials, but only increase/decrease probability that membrane potential reaches the threshhold.
Anodal Stimulation -> activation (i.e. depolarization of membrane potential-> closer to threshold)
Cathodal Stimulation -> inhibition (i.e. hyperpolarization -> away from threshold)
