Disrupted Functional Connectivity with Dopaminergic Midbrain in Cocaine Abusers

The cocaine usage affects the brain activity and neurotransmission. The purpose of the given research was to define how these reactions influence overall function of the brain and its particular segments. The cocaine use (especially repeated) leads to certain reactions in the midbrain (neuroadaptations).

The neuroadaptation in dopaminergic function leads to the decrease of sensitivity, affects the psychological state causing stress conditions and influences on the cognitive function. Such reaction is caused by the neuroadaptations that influences on the functional connectivity of different part of brain that are regulated by dopamine. Thus, we can observe different brain dysfunctions in cocaine abusers.

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The importance of the research lies in the fact that it helps in deeper understanding of the overall brain activity and functional connectivity of the midbrain. The research also shows the influence of cocaine on the brain zones that are responsible for reaction, cognitive function and attention.

The results of this research can contribute to the studies of the brain activity and treatment of the diseases related to the functional connectivity. The basics for the given research were findings that established the role of dopamine in the brain reactions under the influence of drugs with addicted individuals.

The previous researches show that the desire for the drugs is related to the increase of dopamine. Thus, the drug-related words can cause the reaction in the mesencephalon in drug users. The research hypothesized that cocaine addicted individuals have decreased sustained attention and cognitive function. The reason of these processes is the influence of drugs on the brain activity that shows the decrease of the functional connectivity of the midbrain.

In order to provide a research, two groups of people were involved. The first group consisted of twenty healthy cocaine abusers and twenty healthy control subjects. The control subjects were matched to the main group according to age, gender and education. Each person was examined by physicians and neurologists.

The research was based on the comparative analysis of the results of the experiments. Among the methods used was the stimulation paradigm (a drug-word paradigm). Each person from each group was shown a number of neutral and drug-related words.

The results of the experiment were examined through the BOLD-fMRI analyses and RIO analyses. The result of the experiment was the next: the usage of drugs influences on the brain activity, in other words, the intensity of reaction in drug-abused people is lower than in healthy people who do not use drugs.

The results of the research confirmed the previous findings. Both groups performed a number of tests with neutral and drug-related words. The results show that there were no great significances in performance between groups. During the task, the same brain sections were activated at the same degree.

However, the CM and BOLD analysis show that the reaction in the thalamus is higher in control group and it correlates negatively in cocaine subjects in compliance with the number of years of drug usage. Moreover, the experiments show that the reaction of the cocaine abuse subjects on the drug-related words were higher than in control groups.

Thus, the results of the research show that the drug-related words activated the midbrain in cocaine subjects but not in the control, and the midbrain was not activated in cocaine subjects during tests with neutral words (Dardo, et al). However, the overall reaction in control group was better. Consequently, the research confirmed the results of previous studies. It proved that the MDTHA had lower CM and lower BOLD signals for people who take drugs than for healthy people.

The study also showed the connection between hypo-activation and decrees of CM in cerebellum for cocaine abusers. So, we can affirm that the emotional response to the drug-related words caused the reaction in brain that led to the reaction in midbrain of cocaine abusers, that is why the results of the BOLD analysis show the same ability to react and the same brain activity. The rACC activated during the emotional tasks and there were no reaction during the tasks that involved cognitive activity in cocaine abusers.

The results of the research have a great significance for the study of brain activity and the processes that occur in different sections of brain under the influence of external (words, signals, emotions) and internal (drugs) stimulus. The results of the research rejects at some extend the hypothesis.

It goes without saying that the results of definite tasks support the suggestion that drug abusers have lower reaction and brain activity. However, the research shows that the drug usage leads to the abnormal functional connectivity of catecholamine. Thus, the functional connectivity can be more sensitive than standard activation technique (Dardo, et al) with years of drug usage as it is associated with drug addiction.

The research provided the deeper insight into the brain functioning and the impact of drugs on the psychological and physical reactions in the human body. The further research in this direction can be devoted to the question how to prevent such reactions on drugs and how it can contribute to the treatment of the drug addiction.

Works Cited

Dardo, Tomasi et al. “Disrupted Functional Connectivity with Dopaminergic Midbrain in Cocaine Abusers.” PLoS One: National Center for Biotechnology Information, U.S. National Library of Medicine. 5.5. e10815 (2010): n. pag. Web. 7 November. 2010.


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