title: Disentangling the Role of Cortico-Basal Ganglia Loops in Top-Down and Bottom-Up Visual Attention: An Investigation of Attention Deficits in Parkinson Disease.
abstract: It is solidly established that top-down (goal-driven) and bottom-up (stimulus-driven) attention mechanisms depend on distributed cortical networks, including prefrontal and frontoparietal regions. On the other hand, it is less clear whether the BG also contribute to one or the other of these mechanisms, or to both. The current study was principally undertaken to clarify this issue. Parkinson disease (PD), a neurodegenerative disorder primarily affecting the BG, has proven to be an effective model for investigating the contribution of the BG to different brain functions; therefore, we set out to investigate deficits of top-down and bottom-up attention in a selected cohort of PD patients. With this objective in mind, we compared the performance on three computerized tasks of two groups of 12 parkinsonian patients (assessed without any treatment), one otherwise pharmacologically treated and the other also surgically treated, with that of a group of controls. The main behavioral tool for our study was an attentional capture task, which enabled us to tap the competition between top-down and bottom-up mechanisms of visual attention. This task was suitably combined with a choice RT and a simple RT task to isolate any specific deficit of attention from deficits in motor response selection and initiation. In the two groups of patients, we found an equivalent increase of attentional capture but also comparable delays in target selection in the absence of any salient distractor (reflecting impaired top-down mechanisms) and movement initiation compared with controls. In contrast, motor response selection processes appeared to be prolonged only in the operated patients. Our results confirm that the BG are involved in both motor and cognitive domains. Specifically, damage to the BG, as it occurs in PD, leads to a distinct deficit of top-down control of visual attention, and this can account, albeit indirectly, for the enhancement of attentional capture, reflecting weakened ability of top-down mechanisms to antagonize bottom-up control.
authors.affiliation: University of Verona.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Tommasi
authors.forename: Mirta
authors.initials: M
authors.lastname: Fiorio
authors.forename: Jérôme
authors.initials: J
authors.lastname: Yelnik
authors.forename: Paul
authors.initials: P
authors.lastname: Krack
authors.forename: Francesca
authors.initials: F
authors.lastname: Sala
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Schmitt
authors.forename: Valérie
authors.initials: V
authors.lastname: Fraix
authors.forename: Laura
authors.initials: L
authors.lastname: Bertolasi
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Le Bas
authors.forename: Giuseppe Kenneth
authors.initials: GK
authors.lastname: Ricciardi
authors.forename: Antonio
authors.initials: A
authors.lastname: Fiaschi
authors.forename: Jan
authors.initials: J
authors.lastname: Theeuwes
authors.forename: Pierre
authors.initials: P
authors.lastname: Pollak
authors.forename: Leonardo
authors.initials: L
authors.lastname: Chelazzi
mesh_terms: D001288:Attention / Q000502:physiology*; D001479:Basal Ganglia / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D015331:Cohort Studies; D003201:Computers; D046690:Deep Brain Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000188:drug therapy / Q000503:physiopathology* / Q000523:psychology* / Q000601:surgery; D011930:Reaction Time; D014795:Visual Pathways / Q000503:physiopathology; D014796:Visual Perception / Q000502:physiology*