Method: Human Behavior
Article: Curtin J. Hogle J. Kaye J. 2010. Nicotine Withdrawal Increases threat-Induced Anxiety But Not Fear: Neuroadaptation in Human Addiction. Biological Psychiatry. 68: 719-725
Summary: This article attempts to analyze the effect of nicotine withdrawal/addiction on threat-induced anxiety by measuring startle response. Participants were selected who were smokers and placed into 2 different groups. One group experienced electrical shocks randomly while the other group experienced electrical shocks in a predictable manner. Results showed that nicotine withdrawal increased the startle response in those that were in group 1 (experienced the shock randomly). Predictable shocks, however, did not have a significant effect on startle or fear in group 2. This suggests addiction and subsequent withdrawal causes stress neuroadaptations in humans that cause them to experience greater fear or be more anxious in the face of an upredictable threat.
Method: Human Imaging
Article: Thompson P, Hayashi S. Simon J. Michael H. Yihong S. Lee J. Ling W. London E. 2004. Structural Abnormalities in the Brains of Human Subjects Who Use Methamphetamine. Journal of Neuroscience; 24; 6028-6036
Summary: This article analyzes the brains of chronic methamphetamine (MA) users for structural deficits. They used MRI to analyze the structural brain changes in 22 MA users and 21 healthy controls. MRI revealed severe Gray matter deficits in the cingulate, limbic, and paralimbic cortices. Additionally, on average, MA users had 7.8 % smaller hippocampus volumes. MA brains had white matter hypertrophy, neuroadaptation, neuropil reduction, and cell death. These effects were correlated with decreased memory function and word-recall ability. Furthermore, the whaite9matter hypertrophy could have been caused by altered myelination, and glial changes.
Method: Neuroanatomy
Articles: Uhl GR. Koob GF. Cable J. 2019. The neurobioogy of addiction. Ann N Y Acad Sci. 1451: 5-28.
Summary: Using neuroimaging, researchers were able to identify 3 stages of addiction. bing/intoxicaation, withdrawal/negative affect, and preoccupation/anticipation.. These stages apply correspond to three major neurocircuits: basal ganglia, extended amygdala, and prefrontal cortex. Addictive drugs are able to hijack the brain's dopamine system to increase dopamine levels in the nucleus accumbens.
Lesioning
Article: Joutsa J. Moussawi K. Siddiqi SH. et. al. 2022. Brains lesions disrupting addiction map to a common human brain circuit. Nat Med. 28: 1249 - 1255.
Summary: This article attempted to analyze how brain leisoning can affect addiction. Researchers used patients who were addicted to smoking. They lesioned areas of the brain associated with addiction with positive connectivity to dorsal cingulate, lateral prefrontal cortex, and insula and negative connectivity to the medial prefrontal and temporal cortex. Patients who had lesions in certain areas of the brain had associations of addiction remission.
Animal Behavior
Article: Entler BV, Cannon JT, Seid MA. 2016. Morphine addiction in ants: a new model for self-administration and neurochemical analysis. J Exp Biol. 18: 2865-2869
Summary: Mammalian models for studying addictions have had major prevalence. This articles establishes ants as a new model for drug addiction. Useing invertbrates shows how addiction corrupts even basic function. Using a sucrose-fading paradigm followed by a two-dish tests, ants show drug seeking and self-adminstration behavior.