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Slide 9: The reward pathway
Tell students that this is a view of the brain cut down the middle. An important part of the reward system is shown and the major structures are highlighted: the ventral tegmental area (VTA), the nucleus accumbens (nuc. acc.) and the prefrontal cortex. Also, the pathway connecting these structures is highlighted. The information travels from the VTA to the nucleus accumbens and then up to the prefrontal cortex. Reiterate that this pathway is activated by a rewarding stimulus. [Note to scientists - this is not the only pathway activated by reward, other structures are involved too, but only this part of the pathway is shown for simplicity.]
The mechanism that underlies craving may entail recall of emotionally laden previous experiences. Indeed, craving correlated with activation of the amygdala in one study (42), and activation of the orbitofrontal cortex was observed when cocaine abusers recalled and described their own method of preparing cocaine but not when they described their family genealogical tree in a study from our laboratory (45) (Figure 2). In addition, craving may involve anticipation of a future drug reward. The role of the dorsolateral prefrontal cortex in the anticipation of immediate drug self-administration was previously suggested (42), although the dissociation of craving from anticipation and of both from the actual drug experience has not been supported. Nevertheless, the actual drug experience may be related with more circumscribed activations than the anticipation phase (42), in line with evidence for a similar dissociation of anticipation from an actual sensory (tactile) experience (46).
Incremento diferencial de rCBF en amigdala y cingulado anterior (PET; 150 -water)
Activación límbica durante el craving de cocaína inducido con señales