Fig. 10. Effect of the method of drug injection on the distribution of intracarotid drugs. Reconstructed autoradiographic images show distribution of tracer at two levels of a nonhuman primate brain, fronto-parietal cortex (level 1) and through basal ganglia and the temporal lobe (level 2). (A ) Injection of intracarotid tracer as pulses during diastole shows homogenous tissue drug concentrations. (B ) Intravenous infusion of drugs also produces similar homogenous concentration. (C ) Intracarotid infusion of the tracer produces marked variations in tissue tracer concentrations due to streaming. These results suggest that injection of intracarotid drugs as diastole-phase pulses considerably decreases variations in tissue drug concentrations due to streaming. From Saris et al. 157; used with permission.