A persistent vegetative state "brain-death") sometimes follows a coma.Individuals in such a state have lost their thinking abilities and awareness of their surroundings,but retain non-cognitive function and normal sleep patterns.Even though those in a persistent vegetative state lose their higher brain functions,other key functions such as breathing and circulation remain relatively intact.Spontaneous movements may occur, and the eyes may open in response to external stimuli.They may even occasionally grimace(痛苦的表情)，cry,or laugh.n A persistent vegetative state ( “brain-death”) sometimes follows a coma. Individuals in such a state have lost their thinking abilities and awareness of their surroundings, but retain non-cognitive function and normal sleep patterns. Even though those in a persistent vegetative state lose their higher brain functions, other key functions such as breathing and circulation remain relatively intact. Spontaneous movements may occur, and the eyes may open in response to external stimuli. They may even occasionally grimace(痛苦的表情), cry, or laugh