Towards a dopamine hypothesis of hemineglect syndrome

Neglect syndrome is a complex neuropsychological disorder that is associated with difficulties in analyzing stimuli located on the side opposite to the site of brain damage. The occurrence of this deficit is rooted in many cognitive functions (attention, working memory, perceptual abilities, etc.) and motor functions (planning, initiating, inhibiting, speed of movement, etc.). In the search for the neurobiological basis of this syndrome, the classic localization approach still dominates in the neuropsychological literature – which consists in searching for anatomical equivalents of a given disorder and trying to identify the brain area whose damage is crucial for the occurrence of the deficit; this area is considered critical for a given function – or an approach presented in the paradigm of neural networks, which take into account the possibility of simultaneous, distributed information processing. These approaches relatively better explain the deficits observed in neurology, but they cope much worse with complex neuropsychological variables. An alternative to these paradigms – although in a sense analogous to the network approach – is an attempt to capture neuropsychological variables from the perspective of neurotransmitter pathways. This approach has the advantage that, together with theoretical findings, it opens the way to therapeutic interventions; it also allows for a wider application of the clinical experiment method. In this article, attention will be focused on the neurotransmitter that has been best studied in this context so far – dopamine, and specifically on the functioning and disorders of dopamine processing in five basic pathways.