Desmotivadora evolución de la desconexión asimétrica del Núcleo Accumbens en el trastorno por consumo de cocaína: un punto de vista traslacional
Background. Experimental asymmetrical disconnection in animals is a lesion technique used to demonstrate the involvement of specific brain circuits in complex behaviors. Using this surgical technique it has been demonstrated that cortico-limbic-striatal circuits, involving medial prefrontal cortex (mPFC), basolateral amygdala (BLA), and nucleus accumbens (Nacb), regulate decision-making processes. In particular, disruption of Nacb and BLA communication impairs motivated behavior. In addition, disconnections between the BLA and mPFC increase choice of riskier options, suggesting that this circuit facilitates tracking of actions and outcomes to temper urges for riskier rewards and to maintain effort.
Case Description. A young patient with disruptive aggressive behaviors and cocaine abuse problems was diagnosed from “impulse control dysfunction” and “limbic dysfunction syndrome”. Neuroimaging tests indicated atrophy of left hemisphere, and moderate general reduction in brain metabolism. Surgical intervention, very similar to the experimental technique previously described, was employed. Thermal coagulation lesions were targeted at left hemisphere anterior cingulate (AC), anterior capsula (ALIC), and stria terminalis. In the right hemisphere targets were ALIC and amygdala. Two months later, after relapse of aggressivity, a second surgery extended previous lesions in left ALIC and AC in the right hemisphere. Neuroimages after 5 and 15 years demonstrate the extent of those lesions.Conclusions. Recent neuropsychological tests in this patient that assessed frontal and striatal functions show high impulsivity, impairment of planning processes and difficulties in cost/benefit decision making compared with normative samples. There is evidence showing that addiction and schizophrenia have very little improvements from surgical interventions. Moreover, combining more than one brain target may make outcomes worse.
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