The brain spheroids, also known as 3-dimensional brain cultures or cerebral organoids, refer to spherical laboratory-grown human brain tissue with 4mm in diameter. Inside the brain spheroids, thousands of neurons communicate with each other with an electric pulse. As an impressive form of tissue culture, they can't generate emotions and thoughts. Since it is very difficult to connect a functioning circulatory system to the spheroids, it seems impossible in theory to make a larger and more developed sphere.