Current brain imaging technologies constrain our ability to understand how the brain functions. To develop next-generation cogniceuticals we will need to move beyond today's three brain imaging technologies to the level of neuron and intra-neuron scanning.

fMRI's (functional magnetic resonance imaging) have a resolution limit of about a cubic millimeter, this volume can still contain tens of thousands of neurons. PET (positron emission tomography) scans are more accurate in determining where in the brain neurons are being activated but have poor temporal resolution, while EEG's (electro-encephalogram) are more accurate in precisely timing events, they are unable to track important biochemical attributes.

Update 5/20: Current brain imaging still provides only a crude snapshot of brain activity.  Neural processes are thought to occur on a 0.1 millimeter scale in 100 milliseconds (msec), but the spatial and temporal resolution of a typical scanner is only 3 millimeters and about two seconds.