Deep in the brain lies a tiny region called the suprachiasmatic nucleus. It's the conductor that sets the rhythm for the whole body: when to sleep, when to wake, when to release hormones. Scientists took the real connection map of this region from a mouse and made copies — one bigger, one smaller. Like taking a city plan and building both a village and a metropolis from it.
The rhythm turned out to be the same in all three versions — small, medium, and large. The period, oscillation strength, and cell synchrony didn't change. Then scientists added more connections to each cell, and only then did the rhythm strengthen. So it's not about network size, but about how densely cells communicate with each other. If connections are few, the network falls apart and the clock stops. If connections are sufficient, the rhythm holds no matter how many cells you add.
It's like an orchestra: it doesn't matter if there are ten musicians or a hundred — if each one hears their neighbors, the music plays in harmony. But if you put them in separate rooms, even a large orchestra will fall out of sync. That's how biological clocks work: their strength lies in connections, not in cell count.
The suprachiasmatic nucleus contains only about 20,000 neurons, fewer than the number of sand grains in a teaspoon, yet it governs the rhythms of the entire body.