Biology Reference
In-Depth Information
control, whereas the drug-related images included the simulated purchase, preparation and
smoking of cocaine. These protocols also include the evaluation of cocaine related states
using different scales, such as the Within Session Rating Scale, a 10-item scale asking about
the high, craving and withdrawal related to cocaine administered before and after each video.
After the PET or fMRI sessions, each patient has a supportive “talk-down” with a trained
clinician before leaving the facility, which is also useful as a form of therapy to help the
patient to deal with drug-related situations in the future.
Figure 3. Functional brain activation associated with cue-induced cocaine craving in cocaine abusers.
Images illustrate the differential increase in relative regional cerebral blood flow in the amygdala and
anterior cingulate of a detoxified cocaine patient during a non-drug-related (nature) video and a
cocaine-related video. (Source: Adapted from Childress et al., 1999).
Neuroimaging studies of response to drug conditioned cues have reported activation in
different cortical and subcortical regions, including prefrontal cortical areas, especially the
orbitofrontal and anterior cingulate, and the amygdala, a region involved in the stimulus-
reward associations (see figure 3). Some of these studies have also found activation in the
NAc and the dorsal striatum (Grant et al., 1996; Maas et al., 1998; Childress et al., 1999; Kilts
et al., 2001). Interestingly, the lack of hippocampal activation suggested the subordination of
explicit (factual) memory to an amygdala-driven emotional state (Squire et al., 1992). The
neuronal responses obtained with neuroimaging techniques are similar to those recorded with
the same techniques under the effects of psychostimulants such as cocaine. This shows that
brain structures activated during cue-cocaine craving may be among those activated by
cocaine itself (Goldstein and Volkow, 2002). These results support those reported during
abstinence, suggesting that impaired prefrontal function characterizing addiction can be
involved in relapse in drug consumption. In these studies, patient self-reports of craving
correlate positively with activity in the prefrontal cortex (Childress et al., 1999; Goldstein and
Volkow, 2002; Grant et al., 1996) and increased amygdala activity (Childress et al., 1999). It
is important to mention that an increased response to cocaine cues persists for a long time,
even throughout the life span, and can induce relapse years after the last contact with the
