Fig. 6. Evidence that there are fewer GABAAreceptors on motor neurons from −/− compared with +/+ mice. (A ) A GABAAagonist, muscimol, exerts a far smaller depressant effect on the population excitatory postsynaptic potential (EPSP) evoked from cords of −/− than +/+ mice. Muscimol concentration, 1 μm;P < 0.0001; n = 5 of each type. (B ) Relative amplitudes of currents evoked by GABA in a neuron from a +/+ animal compared with one from a −/− animal. Note the difference in calibration mark. Holding potential, −60 mV.