Attentional Focus Modulated by Mesothalamic Dopamine: Consequences in Parkinson’s Disease and Attention Deficit Hyperactivity Disorder

Abstract

In this work, we propose a mathematical model that describes how the mesothalamic dopamine pathway modulates the attentional focus via the thalamocortical loop, and how mesothalamic dopamine alterations can promote inattention symptoms in patients with Parkinson's disease (PD) and attention deficit hyperactivity disorder (ADHD). We model the thalamocortical loop with a neuronal network where each thalamic neuron is described by a system of coupled differential equations reflecting neurophysiological properties. The computational simulations reflect neurochemical features of PD and ADHD. Our results suggest that the mesothalamic dopamine hypoactivity causes difficulties in attentional shifting. Conversely, the mesothalamic dopamine hyperactivity hinders the attentional focus consolidation. Furthermore, regardless of the amount of mesothalamic dopamine activity, the mesocortical dopamine hypoactivity leads to loss of attentional focus. Finally, we identify a unique neuronal mechanism underlying attention deficits in PD and ADHD and relate different inattention symptoms in ADHD to different dopaminergic levels in the brain circuit modeled.

Mesothalamic Dopaminergic Activity: Implications in Sleep Alterations in Parkinson's Disease

“…In (Madureira et al, 2010), we proposed a mathematical model indicating how the mesothalamic dopamine influences the thalamocortical loop, through the TRN, and thus modulates the attentional focus formation. In particular, we investigated relationships between alterations in this dopaminergic pathway and attention deficits in PD and ADHD.…”

“…Investigations on such dopaminergic pathway, evidenced by Freeman and colleagues (Freeman et al, 2001), have been contributing to a more global comprehension of cognitive processes in the brain. Based on experimental results (Florán et al, 2004), the mathematical model proposed in (Madureira et al, 2010) indicates a way by which the mesothalamic dopamine inhibits neurons in the TRN. And computational simulations of this model suggest that alterations in the MDA lead to inattention symptoms as observed in PD and Attention Deficit Hyperactivity Disorder (ADHD).…”

“…By this way, they propagate information reliably from perceptual systems to the cerebral cortex, where a more refined processing takes place. This mode of activity is crucial to the thalamocortical filtering of perceptual stimuli that allows attention focusing (Madureira et al, 2007(Madureira et al, , 2010Carvalho, 1994).…”

“…That is why, under the burst mode, thalamic neurons spike quite autonomously, in such a way that their pattern of activity does not represent the input information. Since the inattention symptoms addressed in (Madureira et al, 2010) concerned awakened people, the model considered the behavior of thalamic neurons under the tonic state. In the present work, we go further with the matter and scrutinize relationships between the MDA and the oscillatory state of neurons in the thalamic complex.…”

Modelagem da influência da nicotina no foco de atenção

“…Tais neurônios, então, projetam-se sobre o tálamo, inibindo T y . Tal mecanismo permeia o foco atencional (para mais detalhes ver [3]). …”