Perhaps you hear scientists and doctors giving presentations about closed loop stimulation? This probably makes you ask, what closed-loop stimulation of the brain? And what is closed-loop brain stimulation useful for?
First let’s contrast closed-loop with open-loop. Now people don’t call it “open-loop brain stimulation”. They just call it brain stimulation. For example, when people say “tDCS” they usually just mean open-loop tDCS. When people say “tACS” they usually just mean open-loop tACS. Same goes for implanted brain stimulation technologies like Deep Brain Stimulation (DBS) and Spinal Cord Stimulation (SCS). With open-loop stimulation a stimulation approach is decided on before-hand and applied to the person. For example, everyone gets 1 mA for 20 minutes of tDCS.
During closed-loop brain stimulation, measurements are made either of brain activity (like an EEG) or of some behavior (like hand shaking) and the stimulation is automatically changed based on this measurement. Usually the way this works is there is a wanted “target” brain activity (like a normal EEG) or behavior (like no tremor) and the stimulation is changed (for example more current) until the wanted brain activity of behavior is achieved.
Closed-loop brain stimulation devices have:
1) A sensor to measure brain activity of a behavior
2) A programmable stimulation device
3) A computer running a control algorithm that decides how to change the stimulation based on the observed behavior, where the goal is to stimulate the brain in order to move the brain activity and behavior toward a targeted state
Want to learn more about closed loop brain stimulation? Here are some videos.
For a general introduction to what closed-loop stimulation is you can watch this talk by Dr. Marom Bikson (though interestingly Dr. Bikson says all brain stimulation is closed-loop in a sense since it is adjusted per person)
And then Dr. Marom Bikson talks about “downloading personalized brain stimulation”
For a deeper technical dive on closed-loop stimulation watch this talk by Dr. Maryam Shanechi
And then Dr. Shanechi applies this to BCI ‘Brain Control Interface”
The common theme in closed-loop stimulation is how stimulation can be “personalized.”
If you are interested in more general videos that explain tDCS, refer to the content below for some interesting reads.