What is sensitised?

Some articles on sensitised:

Von Neumann Cellular Automaton - Definition - States
... They are a ground state U (48, 48, 48) the transition or sensitised states (in 8 substates) S (newly sensitised) (255, 0, 0) S0 - (sensitised, having received no input for one cycle) (255, 125, 0) S00 - (sen ...
Von Neumann Cellular Automaton - Definition - Construction Rules
... transmission state, the cell in the ground state becomes "sensitised," transitioning through a series of states before finally "resting" at a quiescent transmission or confluent state ... Therefore, the transition/sensitised states can be thought of as the nodes of a bifurcation tree leading from the ground-state to each of the quiescent transmission and ... state U, given an input, will transition to the S (newly sensitised) state in the next cycle (1) a cell in the S state, given no input, will transition into the S0 state (10) a ...