Cocaine Dependent Individuals and Gamblers Present Different Associative Learning Anomalies in Feedback-Driven Decision Making: A Behavioral and ERP Study.

Cocaine Dependent Individuals and Gamblers Present Different Associative Learning Anomalies in Feedback-Driven Decision Making: A Behavioral and ERP Study.

Front Psychol. 2013; 4: 122
Torres A, Catena A, Cándido A, Maldonado A, Megías A, Perales JC

Several recent studies have demonstrated that addicts behave less flexibly than healthy controls in the probabilistic reversal learning task (PRLT), in which participants must gradually learn to choose between a probably rewarded option and an improbably rewarded one, on the basis of corrective feedback, and in which preferences must adjust to abrupt reward contingency changes (reversals). In the present study, pathological gamblers (PG) and cocaine dependent individuals (CDI) showed different learning curves in the PRLT. PG also showed a reduced electroencephalographic response to feedback (Feedback-Related Negativity, FRN) when compared to controls. CDI’s FRN was not significantly different either from PG or from healthy controls. Additionally, according to Standardized Low-Resolution Electromagnetic Tomography analysis, cortical activity in regions of interest (previously selected by virtue of their involvement in FRN generation in controls) strongly differed between CDI and PG. However, the nature of such anomalies varied within-groups across individuals. Cocaine use severity had a strong deleterious impact on the learning asymptote, whereas gambling intensity significantly increased reversal cost. These two effects have remained confounded in most previous studies, which can be hiding important associative learning differences between different populations of addicts. HubMed – addiction


Comparison of General Well-being of Patients Undergoing Methadone Maintenance Therapy (MMT) with Patients Undergoing Naltrexone Therapy.

Iran J Public Health. 2013; 42(2): 145-8
Sayyah M, Sharifi M, Rokni P

Drug abuse is a problem that causes a wide array of social, emotional, and physical problems and involves both patients and the society. Helping the addicted has always been a priority for physicians and especially psychiatrists. The purpose of this prospective study was to compare the effects of methadone and naltrexone in general well-being of patients undergoing these treatments.Forty-six patients who were taking either methadone or naltrexone were selected and evaluated for a period of 5 months using a 28-item questionnaire about their general health.In spite of the fact that patients undergoing methadone treatment had more severe symptoms and prognoses regarding their age, duration of drug abuse, and number of treatment attempts, these patients showed better general health and social functioning comparing to patients undergoing naltrexone treatment during the 6-month period of this study (P<0.000).Methadone might be regarded as an effective and useful medicine in treatment of addiction. HubMed – addiction


Distinct extended amygdala circuits for divergent motivational states.

Nature. 2013 Mar 20;
Jennings JH, Sparta DR, Stamatakis AM, Ung RL, Pleil KE, Kash TL, Stuber GD

The co-morbidity of anxiety and dysfunctional reward processing in illnesses such as addiction and depression suggests that common neural circuitry contributes to these disparate neuropsychiatric symptoms. The extended amygdala, including the bed nucleus of the stria terminalis (BNST), modulates fear and anxiety, but also projects to the ventral tegmental area (VTA), a region implicated in reward and aversion, thus providing a candidate neural substrate for integrating diverse emotional states. However, the precise functional connectivity between distinct BNST projection neurons and their postsynaptic targets in the VTA, as well as the role of this circuit in controlling motivational states, have not been described. Here we record and manipulate the activity of genetically and neurochemically identified VTA-projecting BNST neurons in freely behaving mice. Collectively, aversive stimuli exposure produced heterogeneous firing patterns in VTA-projecting BNST neurons. By contrast, in vivo optically identified glutamatergic projection neurons displayed a net enhancement of activity to aversive stimuli, whereas the firing rate of identified GABAergic (?-aminobutyric acid-containing) projection neurons was suppressed. Channelrhodopsin-2-assisted circuit mapping revealed that both BNST glutamatergic and GABAergic projections preferentially innervate postsynaptic non-dopaminergic VTA neurons, thus providing a mechanistic framework for in vivo circuit perturbations. In vivo photostimulation of BNST glutamatergic projections resulted in aversive and anxiogenic behavioural phenotypes. Conversely, activation of BNST GABAergic projections produced rewarding and anxiolytic phenotypes, which were also recapitulated by direct inhibition of VTA GABAergic neurons. These data demonstrate that functionally opposing BNST to VTA circuits regulate rewarding and aversive motivational states, and may serve as a crucial circuit node for bidirectionally normalizing maladaptive behaviours. HubMed – addiction