An atom of iron has at least three different isotopes. what is the difference between an isotope of 55fe and an isotope of 58fe?

The isotopes 55Fe and 58Fe are both Iron, but have a different atomic mass due to the added number of neutrons. Both isotopes have 26 protons, but 55Fe has more neutrons.

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later