What detrmineswether a given solute will form a solution in a given solvent?

It depends on the solubility of the solute in the solvent. For example, sodium chloride dissolves in water, therfore we can form a salt solution. Or, copper does not dissolve in water, therfore we can't obtain a solution.

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