suppose that each higher level in the brain mainly reacts to the changes below it, but over some larger scale of time. If so, then when signals repeat at level A, the 5-Brain will have nothing to say. And if the signals that go up to B form a sequence that repeats—so that the 5-Brain keeps seeing a similar pattern—then the C-Brain will sense a "constant con- dition," and thus have nothing to say to the level above it.