At small R values, the E in Figure grows proportional to the total mass Mtot. In contrast, for larger values, it does with Mtot 2 . The reason for this difference is that for small R values, the (Nat -1) 2 crossing terms involving states A and B in ( ) tend to cancel out, leaving only the Nat same-atom terms. Indeed, this feature motivates deriving ( ) from (8). Consider now quantum superpositions in a neuron. The active (firing) and inactive (resting) states of this type of cell are distinct by the sodium ions that can be inside the axon in the active or outside in the inactive state. The inside/outside positions R are separated by an ion channel membrane (the nodes of Ranvier) 8 nm wide. The number of Na + ions involved in the activation is about 10 6 , distributed over all nodes, each one with about 1 m length (which we take as 2 r  ). Thus, supposing that we have a coherent state composed of the active/inactive state superposition, where only the sodium ions contribute to the gravitational self-energy, we can employ (9) to estimate the collapse time. Using the fitting proposed in Table ,  = 24.9 a0 -2 for the atomic radius Rat = 2.25 Å, yielding a collapse time of about 10 10 s. This value is tremendously longer than the axon recovery time (10 -3 s) and decoherence time due to water molecules and other ions in the environment, estimated in 10 -20 seconds by Tegmark. This decoherence