As an experimental neuroscientist that has recorded fairly extensively from brain organoids, I would advise that these are HIGHLY underdeveloped cultures. When patch clamping, I had to depolarize neurons in a human brain organoid to -25mV to trigger action potentials (normally -60mV is sufficient; healthy neurons resting membrane potential is -70mV) Despite imaging organoids for hours with light sheet—a functional imaging technique that allows for observation of nearly all neurons in the organoid simultaneously, I did not observe any spontaneous action potentials, only diffusive waves of calcium activity.

Of course, not all organoids are created equal, and the protocols around extracellular matrices are improving constantly, but for folks interested in systems neuroscience the organoid field is still too underdeveloped to ask interesting questions around functional activity.