This activity peaked shortly before the volunteers reported that they had reached peak rush, and then the activity began to dissipate, much like the reported rush. No areas of brain activity directly paralleled the ratings for craving. What did seem to be associated with craving was the fact that activity in a few regions continued after all others had stopped. These regions included the nucleus accumbens and the right parahippocampal gyrus, both in the forebrain. Rather, the craving that occurs shortly after taking cocaine may be due to a change in the pattern of brain activity over time.
Many brain regions are active when the volunteers report feelings of rush.
Over time, however, only a few brain regions remain activated. This change in activation pattern may be what causes the subjective experience of craving. These results bear out similar findings in animals. Some of the regions of activity that were associated with rush or craving have been implicated in animal studies as being important in producing the pleasurable feelings associated with cocaine use. The regions include the ventral tegmentum, nucleus accumbens, and basal forebrain.