[A neurocomputational model for the thalamocortical loop: towards a better understanding of attention deficit hyperactivity disorder].
BACKGROUND
Inattention symptoms observed in patients with attention deficit hyperactivity disorder (ADHD) are mostly related to a hypoactivity in the mesocortical dopaminergic pathway. However, mesothalamic dopaminergic variations also affect the attentional control, and possibly lead to attention alterations in ADHD.


OBJECTIVE
Elaborating a neurocomputational model from biochemical knowledge of mesocortical and mesothalamic dopamine systems, to investigate how different levels of mesothalamic dopamine influence the thalamocortical loop, leading to some attention deficits observed in ADHD.


METHODS
First, we model physiological properties of thalamic neurons with a set of mathematical equations. Next, we simulate computationally the modeled thalamocortical loop under different levels of mesothalamic dopamine, and also the mesocortical dopaminergic decrease.


RESULTS
Low levels of mesothalamic dopamine hinders the attentional shift and, high levels of such neuromodulator lead to distraction. When such alterations occur together with a decrease in the mesocortical dopamine level, the attention deficit turns into incapacity of perceiving environmental stimuli, due to a no winner competition between low activated thalamic areas. Inattention in ADHD also has its origins in dopaminergic disturbs throughout the mesothalamic pathway, which enhance a high focusing or do not allow the attention focus consolidation.


CONCLUSIONS
In ADHD, the inattention is related to dopaminergic alterations that are not restricted to the mesocortical system.
Madureira
Daniele Q M
DQ
Computer Systems and Engineering Program, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil. daniele@incc.br
de Carvalho
Luis Alfredo V
LA
Cheniaux
Elie
E
D001289:Attention Deficit Disorder with Hyperactivity / Q000378:metabolism* / Q000503:physiopathology; D003198:Computer Simulation; D004298:Dopamine / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008959:Models, Neurological; D013788:Thalamus / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors
D004298:Dopamine