Objective: Cocaine-related cues have been hypothesized to perpetuate drug abuse by inducing a craving response that prompts drug-seeking behavior. However, the mechanisms, underlying neuroanatomy, and specificity of this neuroanatomy are not yet fully understood.Method: To address these issues, experienced cocaine users (N=17) and comparison subjects (N=14) underwent functional magnetic resonance imaging while viewing three separate films that portrayed 1) individuals smoking crack cocaine, 2) outdoor nature scenes, and 3) explicit sexual content. Candidate craving sites were identified as those that showed significant activation in the cocaine users when viewing the cocaine film. These sites were then required to show significantly greater activation when contrasted with comparison subjects viewing the cocaine film (population specificity) and cocaine users viewing the nature film (content specificity).Results: Brain regions that satisfied these criteria were largely left lateralized and included the frontal lobe (medial and middle frontal gyri, bilateral inferior frontal gyrus), parietal lobe (bilateral inferior parietal lobule), insula, and limbic lobe (anterior and posterior cingulate gyrus). Of the 13 regions identified as putative craving sites,just three(anterior cingulate, right inferior parietal lobule, and the caudate/lateral dorsal nucleus) showed significantly greater activation during the cocaine film than during the sex film in the cocaine users, which suggests that cocaine cues activated similar neuroanatomical substrates as naturally evocative stimuli in the cocaine users. Finally, contrary to the effects of the cocaine film, cocaine users showed a smaller response than the comparison subjects to the sex film.Conclusions: These data suggest that cocaine craving is not associated with a dedicated and unique neuroanatomical circuitry; instead, unique to the cocaine user is the ability of learned, drug-related cues to produce brain activation comparable to that seen with nondrug evocative stimuli in healthy comparison subjects.

Over a recent three year period, approximately 600 individuals responded to newspaper advertisements for research studies requiring healthy, cocaine using subjects. These subjects were screened using a standard phone interview in order to eliminate individuals with known medical or psychiatric illnesses that would exclude them from ongoing neuroimaging studies of drug abuse. Individuals were specifically asked about their hepatitis and HIV status. Of these, 170 subjects passed the phone screen, having no known medical or psychiatric illness outside of cocaine abuse/dependence and were willing to be further evaluated for the studies. These subjects were brought to the Medical College of Wisconsin's General Clinical Research Center and tested for, among other measures, hepatitis B, hepatitis C, and HIV. Of these, 144 completed the examination and all testing. In this cohort of assumed healthy subjects, 47 (33%) tested positive for antibodies to the hepatitis C virus (HCV). Only 7 (5%) tested positive for the hepatitis B surface antigen and 2 (1.4%) to HIV. The demographics of this cohort are 56% African-American, 81% male, 75% never-married, 55% unemployed with a mean age of 36 years. The percentage of subjects reporting any lifetime intravenous drug use among the HCV(+) and the HCV(−) cohorts was 77% vs. 29% respectively. Some routes of HCV transmission are still unclear and may reflect lifestyle or other factors related to cocaine use outside of parenteral drug use. Since almost all HCV infections become chronic, and many progress to chronic active hepatitis, cirrhosis, and ultimately hepatocellular carcinoma, these observations suggest a significant epidemic in an unsuspecting population with little regular access to health care. These individuals also form a large pool for the continued transmission of HCV to the general population. Additional public health interventions are suggested.

As the applications of functional magnetic resonance imaging (fMRI) expand, there is a need for the development of new strategies for data extraction and analysis that do not require the presentation of stimuli in a repeated on/off pattern. A description and evaluation of a method and computer algorithm for the detection and analysis of brain activation patterns following acute drug administration using fMRI are presented. A waveform analysis protocol (WAP) input function has been developed that is based upon the single-dose pharmacokinetics of a drug of interest. As a result of this analysis, regional brain activation can be characterized by its localization and intensity of activation, onset of action, time to peak effect, and duration of action. A global statistical test for significant drug effects based upon the probability of a voxel being activated by a saline vehicle injection is applied to grouped data on a voxel by voxel basis. Representative data are presented using nicotine as a prototypical agent. Using this method, statistically significant drug-induced brain activation has been identified in several key cortical and subcortical brain regions. (C) 1999 Wiley-Liss, Inc.

BACKGROUND:The aim of this study was to determine the existence of, and possible mechanisms for, chronic cocaine use-induced neurotoxicity in the human brain. Because in vivo magnetic resonance spectroscopy (MRS) provides a noninvasive way to detect biochemical and physiological changes in the brain, we sought to specifically determine the neurochemical adaptations in chronic cocaine-dependent subjects. METHODS:Twenty-one cocaine users and 13 non-drug-using, age-matched normal volunteers were recruited for an in vivo proton MRS study. Following screening that included physical examination, histories, and blood testing, cocaine group subjects received a spectral scan on a 1.5-T GE Signa scanner. Spectra were obtained from the left basal ganglia and/or the left thalamus from subjects in both groups using an rf bird-cage type head coil with single-voxel localization. RESULTS:The level of N-acetyl aspartate in the region of left thalamus was lower (17%) in the chronic cocaine user group but not in the region of left basal ganglia, compared with the control group. CONCLUSIONS:These results suggest that chronic cocaine use may induce abnormal neurochemical activity and a state of neuronal dysregulation and/or neurotoxicity. It will now be important to determine if these alterations are reversible during withdrawal and what the functional implications of this observation are with respect to cognitive function and drug relapse.

OBJECTIVE:Nicotine is a highly addictive substance, and cigarette smoking is a major cause of premature death among humans. Little is known about the neuropharmacology and sites of action of nicotine in the human brain. Such knowledge might help in the development of new behavioral and pharmacological therapies to aid in treating nicotine dependence and to improve smoking cessation success rates.METHOD:Functional magnetic resonance imaging, a real-time imaging technique, was used to determine the acute CNS effects of intravenous nicotine in 16 active cigarette smokers. An injection of saline followed by injections of three doses of nicotine (0.75, 1.50, and 2.25 mg/70 kg of weight) were each administered intravenously over 1-minute periods in an ascending, cumulative-dosing paradigm while whole brain gradient-echo, echo-planar images were acquired every 6 seconds during consecutive 20-minute trials.RESULTS:Nicotine induced a dose-dependent increase in several behavioral parameters, including feelings of "rush" and "high" and drug liking. Nicotine also induced a dose-dependent increase in neuronal activity in a distributed system of brain regions, including the nucleus accumbens, amygdala, cingulate, and frontal lobes. Activation in these structures is consistent with nicotine's behavior-arousing and behavior-reinforcing properties in humans.CONCLUSIONS:The identified brain regions have been previously shown to participate in the reinforcing, mood-elevating, and cognitive properties of other abused drugs such as cocaine, amphetamine, and opiates, suggesting that nicotine acts similarly in the human brain to produce its reinforcing and dependence properties.