During develоpment, eаch lоwer mоtor neuron innervаtes mаny muscle fibers, but shortly after birth the number of muscle cells innervated by each neuron decreases so that each muscle cell receives innervation from only one motor neuron. Before birth, the size of the motor unit is ________________ and the strength of contraction from the activation of an individual motor neuron is ________________ than after birth.