Physiological Evidence of Drug Addiction

Limbic System and Cocaine
          As was stated in pathology portion of our web page, the limbic system is affected during drug use. Anna Rose Childress et al. have shown that the limbic system is activated when cocaine craving is induced by environmental cues. As was stated in the psychology portion of our web page, cocaine addicted individuals experience cravings when they encounter cues such as people, places, or paraphernalia associated with cocaine.  In fact just the exposure to these stimuli can elicit similar effects in a person to the effects of cocaine, such as generalized arousal, palpitations, light-headedness, ear ringing, chest tightness, the "taste" of cocaine in the back of the throat, and even euphoria.  Due to these effects, the scientists thought that the cocaine craving may be activated by the same brain structures that are affected by cocaine.  Therefore, they tested the limbic system (the amygdala, anterior cingulate, temporal pole, hippocampus, and orbitofrontal cortex) to see whether it is activated during environmental cue stimulation.  Their subjects were male cocaine abusers who were involved in a treatment program.  The subjects were shown two videos: a cocaine video and a nature video.  The cocaine video showed the purchase, preparation, and the actual smoking of the crack cocaine.  The cocaine patients reported cocaine craving, high, and a wish for rush.  The cocaine-naive subjects did not report cocaine craving or cocaine associated responses.  Through examining the cerebral blood flow (CBF), it was found that limbic regions (amygdala and anterior cingulate) of the detoxified cocaine addicted individuals have a significant increase in regional CBF in response to the cocaine video.  The image below demonstrates their findings.

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