Fig. 4. Responses to an injection of 40 nl glutamate (10^-2moll^-1) 1.5 mm rostral of obex and 0.5 mm lateral to midline at 0.2 mm depth. Note the specific increase in the ventilation amplitude (V_AMP) only (divided vertical line denotes time of injection). Heart rate (f_H), ventilation frequency (f_V), ventral aortic blood pressure (P_VA).