title: [A neurocomputational model for the thalamocortical loop: towards a better understanding of attention deficit hyperactivity disorder].
abstract: 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.
authors: Computer Systems and Engineering Program, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil. daniele@incc.br
authors: Daniele Q M
authors: DQ
authors: Madureira
authors: Luis Alfredo V
authors: LA
authors: de Carvalho
authors: Elie
authors: E
authors: Cheniaux
mesh_terms: 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
chemical_list: D004298:Dopamine