Two objects traveling at the same speed have different velocities if

Let's assume two objects have zero acceleration and they moving in opposite direction ( suppose north and south) at same speed. They are moving with same speed but in different direction..which means they have different velocities. Hence answer to your question is ZERO ACCELERATION.

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