Fig. 3. A schematic drawing of the medulla showing the responses to glutamate injection at each coordinate. Numbers in brackets denote the total number of animals injected at that coordinate. The other numbers above and beneath the symbols at a specific coordinate represent the number of animals that have shown that particular response. Filled symbols depict a decrease, whereas open symbols depict an increase. Note the differences in distribution of the pressor and depressor responses, as well as the excitatory ventilatory responses. Heart rate (f_H), ventilation frequency (fV), ventilation amplitude (V_AMP).